1 This is a work-in-progress. My plan is to wikify the existing text, make any updates/corections/additions I can, and then announce the updated FAQ's exisatance to openafs-info. I have tried to contact the current maintainer, but recieved no response - but the last updated date being what it is, perhaps he has a new email.
5 - Formatting Pass 1: Complete
6 - Update Pass: Not Started
7 - Editing Pass: Not Started
8 - Formatting Pass 2: Not Started
10 -- [[DanielClark]] - 21 Jan 2002
14 Archive-name: afs-faq Version: 1.113 Last-modified: 1950 Thursday 9th July 1998
16 # <a name="AFS frequently asked questions"></a> AFS frequently asked questions
20 This posting contains answers to frequently asked questions about AFS. Your comments and contributions are welcome (email: <mpb@acm.org>)
22 Most newsreaders can skip from topic to topic with control-G.
26 <dd><a href="file:///afs/transarc.com/public/afs-contrib/doc/faq/afs-faq.html" target="_top">file:///afs/transarc.com/public/afs-contrib/doc/faq/afs-faq.html</a> <a href="ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/afs-faq.html" target="_top">ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/afs-faq.html</a> <a href="http://www.angelfire.com/hi/plutonic/afs-faq.html" target="_top">http://www.angelfire.com/hi/plutonic/afs-faq.html</a></dd>
33 <li><a href="#AFS frequently asked questions"> AFS frequently asked questions</a><ul>
34 <li><a href="#0 Preamble"> 0 Preamble</a><ul>
35 <li><a href="#0.01 Purpose and audience"> 0.01 Purpose and audience</a></li>
36 <li><a href="#0.02 Acknowledgements"> 0.02 Acknowledgements</a></li>
37 <li><a href="#0.03 Disclaimer"> 0.03 Disclaimer</a></li>
38 <li><a href="#0.04 Release Notes"> 0.04 Release Notes</a></li>
39 <li><a href="#0.05 Quote"> 0.05 Quote</a></li>
42 <li><a href="#1 General"> 1 General</a><ul>
43 <li><a href="#1.01 What is AFS?"> 1.01 What is AFS?</a></li>
44 <li><a href="#1.02 Who supplies AFS?"> 1.02 Who supplies AFS?</a></li>
45 <li><a href="#1.03 What is /afs?"> 1.03 What is /afs?</a></li>
46 <li><a href="#1.04 What is an AFS cell?"> 1.04 What is an AFS cell?</a></li>
47 <li><a href="#1.05 What are the benefits of u"> 1.05 What are the benefits of using AFS?</a><ul>
48 <li><a href="#1.05.a Cache Manager"> 1.05.a Cache Manager</a></li>
49 <li><a href="#1.05.b Location independence"> 1.05.b Location independence</a></li>
50 <li><a href="#1.05.c Scalability"> 1.05.c Scalability</a></li>
51 <li><a href="#1.05.d Improved security"> 1.05.d Improved security</a></li>
52 <li><a href="#1.05.e Single systems image (SS"> 1.05.e Single systems image (SSI)</a></li>
53 <li><a href="#1.05.f Replicated AFS volumes"> 1.05.f Replicated AFS volumes</a></li>
54 <li><a href="#1.05.g Improved robustness to s"> 1.05.g Improved robustness to server crash</a></li>
55 <li><a href="#1.05.h "Easy to use" networking"> 1.05.h "Easy to use" networking</a></li>
56 <li><a href="#1.05.i Communications protocol"> 1.05.i Communications protocol</a></li>
57 <li><a href="#1.05.j Improved system manageme"> 1.05.j Improved system management capability</a></li>
60 <li><a href="#1.06 Which systems is AFS avail"> 1.06 Which systems is AFS available for?</a></li>
61 <li><a href="#1.07 What does "ls /afs" displa"> 1.07 What does "ls /afs" display in the Internet AFS filetree?</a></li>
62 <li><a href="#1.08 Why does AFS use Kerberos"> 1.08 Why does AFS use Kerberos authentication?</a></li>
63 <li><a href="#1.09 Does AFS work over protoco"> 1.09 Does AFS work over protocols other than TCP/IP?</a></li>
64 <li><a href="#1.10 How can I access AFS from"> 1.10 How can I access AFS from my PC?</a></li>
65 <li><a href="#1.11 How does AFS compare with"> 1.11 How does AFS compare with NFS?</a></li>
68 <li><a href="#2 Using AFS"> 2 Using AFS</a><ul>
69 <li><a href="#2.01 What are the differences b"> 2.01 What are the differences between AFS and a unix filesystem?</a></li>
70 <li><a href="#2.02 What is an AFS protection"> 2.02 What is an AFS protection group?</a></li>
71 <li><a href="#2.03 What are the AFS defined p"> 2.03 What are the AFS defined protection groups?</a></li>
72 <li><a href="#2.04 What is an AFS access cont"> 2.04 What is an AFS access control list (ACL)?</a></li>
73 <li><a href="#2.05 What are the AFS access ri"> 2.05 What are the AFS access rights?</a></li>
74 <li><a href="#2.06 What is pagsh?"> 2.06 What is pagsh?</a></li>
75 <li><a href="#2.07 Why use a PAG?"> 2.07 Why use a PAG?</a></li>
76 <li><a href="#2.08 How can I tell if I have a"> 2.08 How can I tell if I have a PAG?</a></li>
77 <li><a href="#2.09 Can I still run cron jobs"> 2.09 Can I still run cron jobs with AFS?</a></li>
78 <li><a href="#2.10 How much disk space does a"> 2.10 How much disk space does a 1 byte file occupy in AFS?</a></li>
79 <li><a href="#2.11 Is it possible to specify"> 2.11 Is it possible to specify a user who is external to the current AFS cell on an ACL?</a></li>
80 <li><a href="#2.12 Are there any problems pri"> 2.12 Are there any problems printing files in /afs?</a></li>
81 <li><a href="#2.13 Can I create a fifo (aka n"> 2.13 Can I create a fifo (aka named pipe) in /afs?</a></li>
82 <li><a href="#2.14 If an AFS server crashes,"> 2.14 If an AFS server crashes, do I have to reboot my AFS client?</a></li>
83 <li><a href="#2.15 Can I use AFS on my diskle"> 2.15 Can I use AFS on my diskless workstation?</a></li>
84 <li><a href="#2.16 Can I test for AFS tokens"> 2.16 Can I test for AFS tokens from within my program?</a></li>
85 <li><a href="#2.18 Can I klog as two users on"> 2.18 Can I klog as two users on a machine in the same cell?</a></li>
86 <li><a href="#2.19 What are the ~/._afsXXXX f"> 2.19 What are the ~/.__afsXXXX files?</a></li>
89 <li><a href="#3 AFS administration"> 3 AFS administration</a><ul>
90 <li><a href="#3.01 Is there a version of xdm"> 3.01 Is there a version of xdm available with AFS authentication?</a></li>
91 <li><a href="#3.02 Is there a version of xloc"> 3.02 Is there a version of xlock available with AFS authentication?</a></li>
92 <li><a href="#3.03 What is /afs/@cell?"> 3.03 What is /afs/@cell?</a></li>
93 <li><a href="#3.04 Given that AFS data is loc"> 3.04 Given that AFS data is location independent, how does an AFS client determine which server houses the data its user is attempting to access?</a></li>
94 <li><a href="#3.05 Which protocols does AFS u"> 3.05 Which protocols does AFS use?</a></li>
95 <li><a href="#3.06 Are setuid programs execut"> 3.06 Are setuid programs executable across AFS cell boundaries?</a></li>
96 <li><a href="#3.07 How does AFS maintain cons"> 3.07 How does AFS maintain consistency on read-write files?</a></li>
97 <li><a href="#3.08 How can I run daemons with"> 3.08 How can I run daemons with tokens that do not expire?</a></li>
98 <li><a href="#3.10 Is there a way to automati"> 3.10 Is there a way to automatically balance disk usage across fileservers?</a></li>
99 <li><a href="#3.11 Can I shutdown an AFS file"> 3.11 Can I shutdown an AFS fileserver without affecting users?</a></li>
100 <li><a href="#3.12 How can I set up mail deli"> 3.12 How can I set up mail delivery to users with $HOMEs in AFS?</a></li>
101 <li><a href="#3.13 Should I replicate a _Read"> 3.13 Should I replicate a ReadOnly volume on the same partition and server as the ReadWrite volume?</a></li>
102 <li><a href="#3.14 Should I start AFS before"> 3.14 Should I start AFS before NFS in /etc/inittab?</a></li>
103 <li><a href="#3.15 Will AFS run on a multi-ho"> 3.15 Will AFS run on a multi-homed fileserver?</a></li>
104 <li><a href="#3.16 Can I replicate my user's"> 3.16 Can I replicate my user's home directory AFS volumes?</a></li>
105 <li><a href="#3.17 Which TCP/IP ports and pro"> 3.17 Which TCP/IP ports and protocols do I need to enable in order to operate AFS through my Internet firewall?</a></li>
106 <li><a href="#3.18 What is the Andrew Benchma"> 3.18 What is the Andrew Benchmark?</a></li>
107 <li><a href="#3.19 Is there a version of HP V"> 3.19 Is there a version of HP VUE login with AFS authentication?</a></li>
108 <li><a href="#3.20 How can I list which clien"> 3.20 How can I list which clients have cached files from a server?</a></li>
109 <li><a href="#3.21 Do Backup volumes require"> 3.21 Do Backup volumes require as much space as ReadWrite volumes?</a></li>
110 <li><a href="#3.22 Should I run timed on my A"> 3.22 Should I run timed on my AFS client?</a></li>
111 <li><a href="#3.23 Why should I keep /usr/vic"> 3.23 Why should I keep /usr/vice/etc/CellServDB current?</a></li>
112 <li><a href="#3.24 How can I keep /usr/vice/e"> 3.24 How can I keep /usr/vice/etc/CellServDB current?</a></li>
113 <li><a href="#3.25 How can I compute a list o"> 3.25 How can I compute a list of AFS fileservers?</a></li>
114 <li><a href="#3.26 How can I set up anonymous"> 3.26 How can I set up anonymous FTP login to access /afs?</a></li>
115 <li><a href="#3.27 Where can I find the Andre"> 3.27 Where can I find the Andrew Benchmark?</a></li>
118 <li><a href="#4 Getting more information"> 4 Getting more information</a><ul>
119 <li><a href="#4.01 Is there an anonymous FTP"> 4.01 Is there an anonymous FTP site with AFS information?</a></li>
120 <li><a href="#4.02 Which USENET newsgroups di"> 4.02 Which USENET newsgroups discuss AFS?</a></li>
121 <li><a href="#4.03 Where can I get training i"> 4.03 Where can I get training in AFS?</a></li>
122 <li><a href="#4.04 Where can I find AFS resou"> 4.04 Where can I find AFS resources in World Wide Web (WWW)?</a></li>
123 <li><a href="#4.05 Is there a mailing list fo"> 4.05 Is there a mailing list for AFS topics?</a></li>
124 <li><a href="#4.06 Where can I find an archiv"> 4.06 Where can I find an archive of <a href="mailto:info-afs@transarc.com">info-afs@transarc.com</a>?</a></li>
125 <li><a href="#4.07 Where can I find an archiv"> 4.07 Where can I find an archive of alt.filesystems.afs?</a></li>
126 <li><a href="#4.08 Where can I find AFS relat"> 4.08 Where can I find AFS related GIFs?</a></li>
127 <li><a href="#4.09 Gibt es eine deutsche AFS"> 4.09 Gibt es eine deutsche AFS Benutzer Gruppe?</a></li>
128 <li><a href="#4.10 Donde puedo encontrar info"> 4.10 Donde puedo encontrar informacion en Espanol sobre AFS?</a></li>
131 <li><a href="#5 About the AFS faq"> 5 About the AFS faq</a><ul>
132 <li><a href="#5.01 How can I get a copy of th"> 5.01 How can I get a copy of the AFS faq?</a></li>
133 <li><a href="#5.02 How can I get my question"> 5.02 How can I get my question (and answer) into the AFS faq?</a></li>
134 <li><a href="#5.03 How can I access the AFS f"> 5.03 How can I access the AFS faq via the World Wide Web?</a></li>
137 <li><a href="#6 Bibliography"> 6 Bibliography</a></li>
145 ## <a name="0 Preamble"></a> 0 Preamble
147 ### <a name="0.01 Purpose and audience"></a> 0.01 Purpose and audience
149 The aim of this compilation is to provide information about AFS including:
151 - A brief introduction
152 - Answers to some often asked questions
153 - Pointers to further information
155 Definitive and detailed information on AFS is provided in Transarc's AFS manuals ([23], [24], [25]).
157 The intended audience ranges from people who know little of the subject and want to know more to those who have experience with AFS and wish to share useful information by contributing to the faq.
159 ### <a name="0.02 Acknowledgements"></a> 0.02 Acknowledgements
161 The information presented here has been gleaned from many sources. Some material has been directly contributed by people listed below.
163 - I would like to thank the following for contributing:
164 - Pierette Maniago VanRyzin (Transarc)
165 - Lyle Seaman (Transarc)
166 - Joseph Jackson (Transarc)
167 - Dan Lovinger (Microsoft)
168 - Lucien Van Elsen (IBM)
169 - Jim Rees (University of Michigan)
170 - Derrick J. Brashear (Carnegie Mellon University)
171 - Hans-Werner Paulsen (MPI fuer Astrophysik, Garching)
172 - Margo Hikida (Hewlett Packard)
173 - Michael Fagan (IBM)
174 - Robert Malick (National Institute of Health, USA)
175 - Rainer Toebbicke (European Laboratory for Particle Physics, CERN)
176 - Mic Bowman (Transarc)
178 - Bob Oesterlin (IBM)
179 - Pat Wilson (Dartmouth College)
180 - Cristian Espinoza (Pontificia Universidad Catolica de Chile)
181 - Mary Ann DelBusso (Transarc)
182 - Michael Niksch (IBM)
183 - Kelly Chambers (Transarc)
185 - Thanks also to indirect contributors:
189 - Dawn E. Johnson (Transarc)
190 - David Snearline (University of Michigan Engineering)
191 - Rens Troost (New Century Systems)
192 - Anton Knaus (Carnegie Mellon University)
193 - Mike Shaddock (SAS Institute Inc.)
195 If this compilation has any merit then much credit belongs to Pierette for giving inspiration, support, answers, and proof-reading.
197 ### <a name="0.03 Disclaimer"></a> 0.03 Disclaimer
199 I make no representation about the suitability of this information for any purpose.
201 While every effort is made to keep the information in this document accurate and current, it is provided "as is" with no warranty expressed or implied.
203 ### <a name="0.04 Release Notes"></a> 0.04 Release Notes
205 This compilation contains material used with permission of Transarc Corporation. Permission to copy is given provided any copyright notices and acknowledgements are retained.
207 Column 1 is used to indicate changes from the last issue:
212 Changes from the last version are to be found at the end of this file.
216 ### <a name="0.05 Quote"></a> 0.05 Quote
218 "'Tis true; there's magic in the web of it;" Othello, Act 3 Scene 4
219 --William Shakespeare (1564-1616)
223 ## <a name="1 General"></a> 1 General
225 ### <a name="1.01 What is AFS?"></a> 1.01 What is AFS?
227 AFS is a distributed filesystem that enables co-operating hosts (clients and servers) to efficiently share filesystem resources across both local area and wide area networks.
229 The commercial version of AFS is marketed, maintained, and extended by Transarc Corporation.
231 AFS is based on a distributed file system originally developed at the Information Technology Center at Carnegie-Mellon University that was called the "Andrew File System".
233 "Andrew" was the name of the research project at CMU - honouring th founders of the University. Once Transarc was formed and AFS became a product, the "Andrew" was dropped to indicate that AFS had gone beyond the Andrew research project and had become a supported, product quality filesystem. However, there were a number of existing cells that rooted their filesystem as /afs. At the time, changing the root of the filesystem was a non-trivial undertaking. So, to save the early AFS sites from having to rename their filesystem, AFS remained as the name and filesystem root.
235 ### <a name="1.02 Who supplies AFS?"></a> 1.02 Who supplies AFS?
237 There are currently three sources for AFS: Commercial Transarc (now part of IBM), the open sourced version of former Transarc AFS called [[OpenAFS]] and the independent open source project Arla.
239 1. Transarc Corporation phone: +1 (412) 338-4400
241 707 Grant Street fax: +1 (412) 338-4404
243 PA 15219 email: information@transarc.com
244 United States of America afs-sales@transarc.com
246 WWW: http://www.transarc.com
248 2. OpenAFS WWW: http://www.openafs.org/
250 3. Arla WWW: http://www.stacken.kth.se/projekt/arla/
252 ### <a name="1.03 What is /afs?"></a> 1.03 What is /afs?
254 The root of the AFS filetree is /afs. If you execute "ls /afs" you will see directories that correspond to AFS cells (see below). These cells may be local (on same LAN) or remote (eg halfway around the world).
256 With AFS you can access all the filesystem space under /afs with commands you already use (eg: cd, cp, rm, and so on) provided you have been granted permission (see AFS ACL below).
258 ### <a name="1.04 What is an AFS cell?"></a> 1.04 What is an AFS cell?
260 An AFS cell is a collection of servers grouped together administratively and presenting a single, cohesive filesystem. Typically, an AFS cell is a set of hosts that use the same Internet domain name.
262 Normally, a variation of the domain name is used as the AFS cell name.
264 Users log into AFS client workstations which request information and files from the cell's servers on behalf of the users.
266 ### <a name="1.05 What are the benefits of u"></a> 1.05 What are the benefits of using AFS?
268 The main strengths of AFS are its:
272 - simplicity of addressing
274 - communications protocol
276 Here are some of the advantages of using AFS in more detail:
278 #### <a name="1.05.a Cache Manager"></a> 1.05.a Cache Manager
280 AFS client machines run a Cache Manager process. The Cache Manager maintains information about the identities of the users logged into the machine, finds and requests data on their behalf, and keeps chunks of retrieved files on local disk.
282 The effect of this is that as soon as a remote file is accessed a chunk of that file gets copied to local disk and so subsequent accesses (warm reads) are almost as fast as to local disk and considerably faster than a cold read (across the network).
284 Local caching also significantly reduces the amount of network traffic, improving performance when a cold read is necessary.
286 #### <a name="1.05.b Location independence"></a> 1.05.b Location independence
288 Unlike NFS, which makes use of /etc/filesystems (on a client) to map (mount) between a local directory name and a remote filesystem, AFS does its mapping (filename to location) at the server. This has the tremendous advantage of making the served filespace location independent.
290 Location independence means that a user does not need to know which fileserver holds the file, the user only needs to know the pathname of a file. Of course, the user does need to know the name of the AFS cell to which the file belongs. Use of the AFS cellname as the second part of the pathname (eg: /afs/$AFSCELL/somefile) is helpful to distinguish between file namespaces of the local and non-local AFS cells.
292 To understand why such location independence is useful, consider having 20 clients and two servers. Let's say you had to move a filesystem "/home" from server a to server b.
294 Using NFS, you would have to change the /etc/filesystems file on 20 clients and take "/home" off-line while you moved it between servers.
296 With AFS, you simply move the AFS volume(s) which constitute "/home" between the servers. You do this "on-line" while users are actively using files in "/home" with no disruption to their work.
298 (Actually, the AFS equivalent of "/home" would be /afs/$AFSCELL/home where $AFSCELL is the AFS cellname.)
300 #### <a name="1.05.c Scalability"></a> 1.05.c Scalability
302 With location independence comes scalability. An architectural goal of the AFS designers was client/server ratios of 200:1 which has been successfully exceeded at some sites. Transarc do not recommend customers use the 200:1 ratio. A more cautious value of 50:1 is expected to be practical in most cases. It is certainly possible to work with a ratio somewhere between these two values. Exactly what value depends on many factors including: number of AFS files, size of AFS files, rate at which changes are made, rate at which file are being accessed, speed of servers processor, I/O rates, and network bandwidth.
304 AFS cells can range from the small (1 server/client) to the massive (with tens of servers and thousands of clients). Cells can be dynamic: it is simple to add new fileservers or clients and grow the computing resources to meet new user requirements.
306 #### <a name="1.05.d Improved security"></a> 1.05.d Improved security
308 Firstly, AFS makes use of Kerberos to authenticate users. This improves security for several reasons:
310 - passwords do not pass across the network in plaintext
312 - encrypted passwords no longer need to be visible
313 - You don't have to use NIS, aka yellow pages, to distribute /etc/passwd - thus "ypcat passwd" can be eliminated.
314 - If you do choose to use NIS, you can replace the password field with "X" so the encrypted password is not visible. (These issues are discussed in detail in [25]).
316 - AFS uses mutual authentication - both the service provider and service requester prove their identities
318 Secondly, AFS uses access control lists (ACLs) to enable users to restrict access to their own directories.
320 #### <a name="1.05.e Single systems image (SS"></a> 1.05.e Single systems image (SSI)
322 Establishing the same view of filestore from each client and server in a network of systems (that comprise an AFS cell) is an order of magnitude simpler with AFS than it is with, say, NFS.
324 This is useful to do because it enables users to move from workstation to workstation and still have the same view of filestore. It also simplifies part of the systems management workload.
326 In addition, because AFS works well over wide area networks the SSI is also accessible remotely.
328 As an example, consider a company with two widespread divisions (and two AFS cells): ny.acme.com and sf.acme.com. Mr Fudd, based in the New York office, is visiting the San Francisco office.
330 Mr. Fudd can then use any AFS client workstation in the San Francisco office that he can log into (a unprivileged guest account would suffice). He could authenticate himself to the ny.acme.com cell and securely access his New York filespace.
334 The following shows a guest in the sf.acme.com AFS cell:
336 1. add AFS executables directory to PATH
337 2. obtaining a PAG with pagsh command (see 2.06)
338 3. use the klog command to authenticate into the ny.acme.com AFS cell
339 4. making a HOME away from home
340 5. invoking a homely .profile
342 guest@toontown.sf.acme.com $ PATH=/usr/afsws/bin:$PATH # {1}
343 guest@toontown.sf.acme.com $ pagsh # {2}
344 $ klog -cell ny.acme.com -principal elmer # {3}
346 $ HOME=/afs/ny.acme.com/user/elmer; export HOME # {4}
352 It is not necessary for the San Francisco sys admin to give Mr. Fudd an AFS account in the sf.acme.com cell. Mr. Fudd only needs to be able to log into an AFS client that is:
354 1. on the same network as his cell and
355 2. his ny.acme.com cell is mounted in the sf.acme.com cell (as would certainly be the case in a company with two cells).
357 #### <a name="1.05.f Replicated AFS volumes"></a> 1.05.f Replicated AFS volumes
359 AFS files are stored in structures called Volumes. These volumes reside on the disks of the AFS file server machines. Volumes containing frequently accessed data can be read-only replicated on several servers.
361 Cache managers (on users client workstations) will make use of replicate volumes to load balance. If accessing data from one replicate copy, and that copy becomes unavailable due to server or network problems, AFS will automatically start accessing the same data from a different replicate copy.
363 An AFS client workstation will access the closest volume copy. By placing replicate volumes on servers closer to clients (eg on same physical LAN) access to those resources is improved and network traffic reduced.
365 #### <a name="1.05.g Improved robustness to s"></a> 1.05.g Improved robustness to server crash
367 The Cache Manager maintains local copies of remotely accessed files. This is accomplished in the cache by breaking files into chunks of up to 64k (default chunk size). So, for a large file, there may be several chunks in the cache but a small file will occupy a single chunk (which will be only as big as is needed).
369 A "working set" of files that have been accessed on the client is established locally in the client's cache (copied from fileserver(s)).
371 If a fileserver crashes, the client's locally cached file copies remain readable but updates to cached files fail while the server is down.
373 Also, if the AFS configuration has included replicated read-only volumes then alternate fileservers can satisfy requests for files from those volumes.
375 #### <a name="1.05.h "Easy to use" networking"></a> 1.05.h "Easy to use" networking
377 Accessing remote file resources via the network becomes much simpler when using AFS. Users have much less to worry about: want to move a file from a remote site? Just copy it to a different part of /afs.
379 Once you have wide-area AFS in place, you don't have to keep local copies of files. Let AFS fetch and cache those files when you need them.
381 #### <a name="1.05.i Communications protocol"></a> 1.05.i Communications protocol
383 AFS communications protocol is optimized for Wide Area Networks. Retransmitting only the single bad packet in a batch of packets and allowing the number of unacknowledged packets to be higher (than in other protocols, see [4]).
385 #### <a name="1.05.j Improved system manageme"></a> 1.05.j Improved system management capability
387 Systems administrators are able to make configuration changes from any client in the AFS cell (it is not necessary to login to a fileserver).
389 With AFS it is simple to effect changes without having to take systems off-line.
393 A department (with its own AFS cell) was relocated to another office. The cell had several fileservers and many clients. How could they move their systems without causing disruption?
395 First, the network infrastructure was established to the new location. The AFS volumes on one fileserver were migrated to the other fileservers. The "freed up" fileserver was moved to the new office and connected to the network.
397 A second fileserver was "freed up" by moving its AFS volumes across the network to the first fileserver at the new office. The second fileserver was then moved.
399 This process was repeated until all the fileservers were moved.
401 All this happened with users on client workstations continuing to use the cell's filespace. Unless a user saw a fileserver being physically moved (s)he would have no way to tell the change had taken place.
403 Finally, the AFS clients were moved - this was noticed!
405 ### <a name="1.06 Which systems is AFS avail"></a> 1.06 Which systems is AFS available for?
407 AFS runs on systems from: HP, Compaq, IBM, SUN, SGI, Apple ([[MacOSX]]) and PCs with flavours of Unix.
409 AFS has been available for Next and DEC (Ultrix).
411 Transarc customers have done ports to Crays, and the 3090, but all are based on some flavour of unix. Some customers have done work to make AFS data available to PCs and Macs, although they are using something similar to the AFS/NFS translator (a system that enables "NFS only" clients to NFS mount the AFS filetree /afs).
413 There is a client only implementation "AFS Client for Windows/NT".
415 A page describing the current systems for which AFS is supported may be found at:
417 - <http://www.transarc.com/Support/afs/relversions/platforms.html>
419 There are also ports of AFS done by customers available from Transarc on an "as is" unsupported basis.
421 More information on this can be found at:
423 - /afs/transarc.com/public/afs-contrib/bin/README
424 - <ftp://ftp.transarc.com/pub/afs-contrib/bin/README>
426 These ports of AFS client code include:
428 - HP (Apollo) Domain OS - by Jim Rees at the University of Michigan.
429 - sun386i - by Derek Atkins and Chris Provenzano at MIT.
430 - Linux - by Derek Atkins, mailing list: <linux-afs-request@mit.edu> <http://www.mit.edu:8008/menelaus/linux-afs/>
431 - [[NetBSD]] - by John Kohl, mailing list: <netbsd-afs@mit.edu>
433 There is some information about AFS on OS/2 at:
435 - <http://www.club.cc.cmu.edu/~jgrande/afsos2.html>
437 The AFS on Linux FAQ may be found at:
439 - <http://www.umlug.umd.edu/linuxafs/>
441 Check out the [[OpenAFS]] and Arla pages for port avilablity.
443 ### <a name="1.07 What does "ls /afs" displa"></a> 1.07 What does "ls /afs" display in the Internet AFS filetree?
445 Essentially this displays the AFS cells that co-operate in the Internet AFS filetree.
447 Note that the output of this will depend on the cell you do it from; a given cell may not have all the publicly advertised cells available, and it may have some cells that aren't advertised outside of the given site.
449 The definitive source for this information is:
451 - <file:///afs/transarc.com/service/etc/CellServDB.export>
453 I've included the list of cell names included in it below:
456 uni-freiburg.de #Albert-Ludwigs-Universitat Freiburg
457 anl.gov #Argonne National Laboratory
458 fl.mcs.anl.gov # Argonne National Laboratory MCS Division FL
459 dapnia.saclay.cea.fr #Axlan-CEA
460 bcc.ac.uk #Bloomsbury Computing Consortium
461 bu.edu #Boston University
462 cs.brown.edu #Brown University Department of Computer Science
463 caspur.it #CASPUR Inter-University Computing Consortium,Rome
465 mathematik-cip.uni-stuttgart.de #CIP-Pool of Math. Dept, Univ. Stuttgart
466 gg.caltech.edu #Caltech Computer Graphics Group
467 cards.com #Cards - Electronic Warfare Associates
468 cheme.cmu.edu #Carnegie Mellon Univ. Chemical Engineering Dept.
469 cmu.edu #Carnegie Mellon University
470 andrew.cmu.edu #Carnegie Mellon University - Campus
471 ce.cmu.edu #Carnegie Mellon University - Civil Eng. Dept.
472 ece.cmu.edu #Carnegie Mellon University - Elec. Comp. Eng. Dept.
473 me.cmu.edu #Carnegie Mellon University - Mechanical Engineering
474 cs.cmu.edu #Carnegie Mellon University - School of Comp. Sci.
475 club.cc.cmu.edu #Carnegie Mellon University Computer Club
476 cert.org #CERT/Coordination Center
477 others.chalmers.se #Chalmers University of Technology - General users
478 cipool.uni-stuttgart.de #CIP Pool, Rechenzentrum University of Stuttgart
479 clarkson.edu #Clarkson University, Potsdam, USA
480 msc.cornell.edu #Cornell University Materials Science Center
481 graphics.cornell.edu #Cornell University Program of Computer Graphics
482 theory.cornell.edu #Cornell University Theory Center
483 ifh.de #DESY-IfH Zeuthen
484 northstar.dartmouth.edu #Dartmouth College, Project Northstar
485 desy.de #Deutsches Elektronen-Synchrotron
486 dkrz.de #Deutsches Klimarechenzentrum Hamburg
487 dis.uniroma1.it #DIS, Univ. "La Sapienza", Rome, area Buonarotti
488 msrc.pnl.gov #EMSL's AFS Cell
489 zdvpool.uni-tuebingen.de#Eberhard-Karls-Universitaet Tuebingen, WS-Pools
491 es.net #Energy Sciences Net
492 research.ec.org #Esprit Research Network of Excellence
493 dce.emsl.pnl.gov #EMSL's DCE Cell
494 cern.ch #European Laboratory for Particle Physics, Geneva
495 fnal.gov #Fermi National Acclerator Laboratory
496 fh-heilbronn.de #Fachhochschule Heilbronn
497 hephy.at #hephy-vienna
498 sleeper.nsa.hp.com #HP Cupertino
499 palo_alto.hpl.hp.com #HP Palo Alto
500 afs.hursley.ibm.com #IBM Hursley Laboratories (UK), external cell
501 ibm.uk #IBM UK, AIX Systems Support Centre
502 zurich.ibm.ch #IBM Zurich Internet Cell
503 ctp.se.ibm.com #IBM/4C, Chalmers, Sweden
504 ipp-hgw.mpg.de #IPP site at Greifswald
505 in2p3.fr #IN2P3 production cell
506 lngs.infn.it #INFN Laboratori Nazionali di Gran Sasso, Italia
507 le.infn.it #INFN Sezione di Lecce, Italia
508 pi.infn.it #INFN Sezione di Pisa
509 ike.uni-stuttgart.de #Institut fuer Kernenergetik, Universitaet Stuttgart
510 ipp-garching.mpg.de #Institut fuer Plasmaphysik
511 csv.ica.uni-stuttgart.de #Institut fuer Computeranwendungen, Uni. Stuttgart
512 iastate.edu #Iowa State University
513 infn.it #Istituto Nazionale di Fisica Nucleare, Italia
514 jpl.nasa.gov #Jet Propulsion Laboratory
515 zdv.uni-mainz.de #Johannes-Gutenberg-Universitaet Mainz
516 isk.kth.se #KTH College of Engineering
517 cc.keio.ac.jp #Keio University, Fac. of Sci. & Tech. Computing Ctr
518 sfc.keio.ac.jp #Keio University, Japan
519 afs-math.zib-berlin.de #Konrad-Zuse-Zentrum fuer Informationstechnik Berlin
520 thermo-a.mw.tu-muenchen.de #Lehrstuhl A fuer Thermodynamik,TUM
521 lrz-muenchen.de #Leibniz-Rechenzentrum Muenchen Germany
522 athena.mit.edu #MIT/Athena cell
523 net.mit.edu #MIT/Network Group cell
524 sipb.mit.edu #MIT/SIPB cell
525 msu.edu #Michigan State University home cell
526 mpa-garching.mpg.de #Max-Planck-Institut fuer Astrophysik
527 federation.atd.net #Multi Resident AFS at Naval Research Lab - CCS
528 isl.ntt.jp #NTT Information and Communication
529 nersc.gov #National Energy Research Supercomputer Center
530 alw.nih.gov #National Institutes of Health
531 nrel.gov #National Renewable Energy Laboratory
532 cmf.nrl.navy.mil #Naval Research Lab
533 lcp.nrl.navy.mil #Naval Research Lab - Lab for Computational Physics
534 nrlfs1.nrl.navy.mil #Naval Research Laboratory
535 eos.ncsu.edu #NCSU - College of Engineering
536 unity.ncsu.edu #NCSU Campus
537 ncat.edu #North Carolina Agricultural and Technical State U.
538 bp.ncsu.edu #North Carolina State University - Backbone Prototype
539 ri.osf.org #OSF Research Institute
540 gr.osf.org #OSF Research Institute, Grenoble
541 urz.uni-magdeburg.de #Otto-von-Guericke-Universitaet, Magdeburg
542 N ovpit.indiana.edu #OVPIT at Indiana University
543 psc.edu #PSC (Pittsburgh Supercomputing Center)
545 phy.bnl.gov #Physics Deptpartment, Brookhaven National Lab
546 postech.ac.kr #Pohang University of Science
547 pppl.gov #Princeton Plasma Physics Laboratory
548 rwcp.or.jp #Real World Computer Partnership(rwcp)
549 rz.uni-jena.de #Rechenzentrum University of Jena, Germany
550 rhrk.uni-kl.de #Rechenzentrum University of Kaiserslautern
551 rus.uni-stuttgart.de #Rechenzentrum University of Stuttgart
552 rhic #Relativistic Heavy Ion Collider
553 rpi.edu #Rensselaer Polytechnic Institute
554 uni-bonn.de #Rheinische Friedrich Wilhelm Univesitaet Bonn
555 rose-hulman.edu #Rose-Hulman Institute of Technology
556 cs.rose-hulman.edu # Rose-Hulman Inst. of Tech., CS Department
557 nada.kth.se #Royal Institute of Technology, NADA
558 rl.ac.uk #Rutherford Appleton Lab, England
559 slac.stanford.edu #Stanford Linear Accelerator Center
560 dsg.stanford.edu #Stanford Univ. - Comp. Sci. - Distributed Systems
561 ir.stanford.edu #Stanford University
562 afs1.scri.fsu.edu #Supercomputer Computations Research Instit
563 ethz.ch #Swiss Federal Inst. of Tech. - Zurich, Switzerland
564 hrzone.th-darmstadt.de #TH-Darmstadt
565 tu-bs.de #Technical University of Braunschweig, Germany
566 tu-chemnitz.de #Technische Universitaet Chemnitz-Zwickau, Germany
567 telos.com #Telos Systems Group - Chantilly, Va.
568 transarc.com #Transarc Corporation
569 cats.ucsc.edu #UC Santa Cruz, Comp and Tech Services, California
570 umr.edu #UMR - Missouri's Technological University
571 hep.net #US High Energy Physics Information cell
572 uni-mannheim.de #Uni Mannheim (Rechenzentrum)
573 ece.ucdavis.edu #Univ California - Davis campus
574 geo.uni-koeln.de #Univ. of Cologne Inst. for Geophysics & Meteorology
575 meteo.uni-koeln.de #Univ. of Cologne Inst. for Geophysics & Meteorology
576 N dsi.uniroma1.it #Univ. Rome-1, Dept. of Computer Science
577 U spv.uniroma1.it #Univ. Rome-1, Area San Pietro in Vincoli
578 N vn.uniroma3.it #Univ. Rome-3, Area Vasca Navale
579 urz.uni-heidelberg.de #Universitaet Heidelberg
580 spc.uchicago.edu #University of Chicago - Social Sciences
581 rrz.uni-koeln.de #University of Cologne - Reg Comp Center
582 wu-wien.ac.at #University of Economics, Vienna, Austria
583 uni-hohenheim.de #University of Hohenheim
584 ncsa.uiuc.edu #University of Illinois
585 wam.umd.edu #University of Maryland Network WAM Project
586 glue.umd.edu #University of Maryland - Project Glue
587 engin.umich.edu #University of Michigan - CAEN
588 umich.edu #University of Michigan - Campus
589 dmsv.med.umich.edu #University of Michigan - DMSV
590 citi.umich.edu #University of Michigan - IFS Development
591 lsa.umich.edu #University of Michigan - LSA College
592 math.lsa.umich.edu #University of Michigan - Math Cell
593 sph.umich.edu #University of Michigan -- School of Public
594 cs.unc.edu #University of North Carolina at Chapel Hill
595 nd.edu #University of Notre Dame
596 pitt.edu #University of Pittsburgh
597 vn.uniroma3.it #University of Rome 3, Area Vasca Navale, Italy
598 isi.edu #University of Southern California/ISI
599 dce.uni-stuttgart.de #University of Stuttgart - DCE/DFS Cell
600 ihf.uni-stuttgart.de #University of Stuttgart, Ins. fuer Hochfrequenz-Tec
601 mathematik.uni-stuttgart.de #University of Stuttgart, Math Dept.
602 cs.utah.edu #University of Utah Computer Science Dept
603 utah.edu #University of Utah Information Tech. Service
604 cs.washington.edu #University of Washington Comp Sci Department
605 wisc.edu #University of Wisconsin-Madison, Campus
606 cs.wisc.edu #University of Wisconsin-Madison, Comp Sci Dept
607 belwue.uni-tuebingen.de #ZDV Universitaet Tuebingen
609 This shows different and widespread organizations making use of the Internet AFS filetree.
611 Note that it is also possible to use AFS "behind the firewall" within the confines of your organization's network - you don't have to participate in the Internet AFS filetree.
613 Indeed, there are lots of benefits of using AFS on a local area network without using the WAN capabilities.
615 ### <a name="1.08 Why does AFS use Kerberos"></a><a name="1.08 Why does AFS use Kerberos "></a> 1.08 Why does AFS use Kerberos authentication?
617 It improves security.
619 Kerberos uses the idea of a trusted third party to prove identification. This is a bit like using a letter of introduction or quoting a referee who will vouch for you.
621 When a user authenticates using the klog command (s)he is prompted for a password. If the password is accepted the Kerberos Authentication Server (KAS) provides the user with an encrypted token (containing a "ticket granting ticket").
623 From that point on, it is the encrypted token that is used to prove the user's identity. These tokens have a limited lifetime (typically a day) and are useless when expired.
625 In AFS, it is possible to authenticate into multiple AFS cells. A summary of the current set of tokens held can be displayed by using the "tokens" command.
629 elmer@toontown $ tokens
631 Tokens held by the Cache Manager:
633 User's (AFS ID 9997) tokens for afs@ny.acme.com [Expires Sep 15 06:50]
634 User's (AFS ID 5391) tokens for afs@sf.acme.com [Expires Sep 15 06:48]
637 Kerberos improves security because a users's password need only be entered once (at klog time).
639 AFS uses Kerberos to do complex mutual authentication which means that both the service requester and the service provider have to prove their identities before a service is granted.
641 Transarc's implementation of Kerberos is slightly different from MIT Kerberos V4 but AFS can work with either version. Joe Jackson wrote about this in: <http://www.cs.cmu.edu/afs/andrew.cmu.edu/usr/shadow/www/afs/afs-with-kerberos.html>
643 For more detail on this and other Kerberos issues see the faq for Kerberos (posted to news.answers and comp.protocols.kerberos) [28]. (Also, see [15], [16], [26], [27])
645 ### <a name="1.09 Does AFS work over protoco"></a> 1.09 Does AFS work over protocols other than TCP/IP?
647 No. AFS was designed to work over TCP/IP.
649 ### <a name="1.10 How can I access AFS from"></a><a name="1.10 How can I access AFS from "></a> 1.10 How can I access AFS from my PC?
651 You can use PC-Interface which is available from Transarc and Locus Computing Corporations.
653 For more information on PC-Interface see the PC-Interface Frequently Asked Questions file in:
655 - <file:///afs/transarc.com/public/afs-contrib/doc/faq/pci.faq>
656 - <ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/pci.faq>
658 There is also SAMBA (an SMB/netbios server for UNIX). The current version will authenticate the connecting process with AFS as well.
660 - <http://samba.anu.edu.au/samba/>
664 - <http://samba.anu.edu.au/samba/docs/faq/sambafaq-1.html#ss1.1>
666 The SAMBA mailing list can be joined via: <samba-request@anu.edu.au>
668 ### <a name="1.11 How does AFS compare with"></a><a name="1.11 How does AFS compare with "></a> 1.11 How does AFS compare with NFS?
670 <table border="1" cellpadding="0" cellspacing="0">
673 <th align="center" bgcolor="#99CCCC"><strong> AFS </strong></th>
674 <th align="center" bgcolor="#99CCCC"><strong> NFS </strong></th>
677 <th bgcolor="#99CCCC"><strong> File Access </strong></th>
678 <td> Common name space from all workstations </td>
679 <td> Different file names from different workstations </td>
682 <th bgcolor="#99CCCC"><strong> File Location Tracking </strong></th>
683 <td> Automatic tracking by file system processes and databases </td>
684 <td> Mountpoints to files set by administrators and users </td>
687 <th bgcolor="#99CCCC"><strong> Performance </strong></th>
688 <td> Client caching to reduce network load; callbacks to maintain cache consistency </td>
689 <td> No local disk caching; limited cache consistency </td>
692 <th bgcolor="#99CCCC"><strong> Andrew Benchmark (5 phases, 8 clients) </strong></th>
693 <td> Average time of 210 seconds/client </td>
694 <td> Average time of 280 seconds/client </td>
697 <th bgcolor="#99CCCC"><strong> Scaling capabilities </strong></th>
698 <td> Maintains performance in small and very large installations </td>
699 <td> Best in small to mid-size installations </td>
703 <td> Excellent performance on wide-area configuration </td>
704 <td> Best in local-area configurations </td>
707 <th bgcolor="#99CCCC"><strong> Security </strong></th>
708 <td> Kerberos mutual authentication </td>
709 <td> Security based on unencrypted user ID's </td>
713 <td> Access control lists on directories for user and group access </td>
714 <td> No access control lists </td>
717 <th bgcolor="#99CCCC"><strong> Availability </strong></th>
718 <td> Replicates read-mostly data and AFS system information </td>
719 <td> No replication </td>
722 <th bgcolor="#99CCCC"><strong> Backup Operation </strong></th>
723 <td> No system downtime with specially developed AFS Backup System </td>
724 <td> Standard UNIX backup system </td>
727 <th bgcolor="#99CCCC"><strong> Reconfiguration </strong></th>
728 <td> By volumes (groups of files) </td>
729 <td> Per-file movement </td>
733 <td> No user impact; files remain accessible during moves, and file names do not change </td>
734 <td> Users lose access to files and filenames change (mountpoints need to be reset) </td>
737 <th bgcolor="#99CCCC"><strong> System Management </strong></th>
738 <td> Most tasks performed from any workstation </td>
739 <td> Frequently involves telnet to other workstations </td>
742 <th bgcolor="#99CCCC"><strong> Autonomous Architecture </strong></th>
743 <td> Autonomous administrative units called cells, in addition to file servers and clients </td>
744 <td> File servers and clients </td>
748 <td> No trust required between cells </td>
749 <td> No security distinctions between sites </td>
754 <td colspan="2"> [ source: <a href="ftp://ftp.transarc.com/pub/afsps/doc/afs-nfs.comparison" target="_top">ftp://ftp.transarc.com/pub/afsps/doc/afs-nfs.comparison</a> ] </td>
760 - Some vendors offer more secure versions of NFS but implementations vary. Many NFS ports have no extra security features (such as Kerberos).
762 - The AFS Cache Manager can be configured to work with a RAM (memory) based cache. This offers signifigant performance benefits over a disk based cache. NFS has no such feature. Imagine how much faster it is to access files cached into RAM!
764 - The Andrew benchmark demonstrates that AFS has better performance than NFS as the number of clients increases. A graph of this (taken from Andrew benchmark report) is available in:
765 - 
767 ## <a name="2 Using AFS"></a> 2 Using AFS
769 ### <a name="2.01 What are the differences b"></a> 2.01 What are the differences between AFS and a unix filesystem?
771 Essentially, from a user's point of view, there is little difference between AFS and local unix filestore. Nearly all the commands normally used to access local files can be used to access files in /afs.
773 In the following set of sections, I have attempted to "target" each section to an appropriate type of user by including to the right of each section heading one of: User, Programmer, [[SysAdmin]].
775 Here is a summary of the differences:
777 **Authentication:** [ User ]
779 Before a user can access protected AFS files (s)he needs to become authenticated to AFS using the klog command (Kerberos login) to get a Kerberos "ticket granting ticket" (called a token from here on).
781 Without a token, an unauthenticated user is given the AFS identity "system:anyuser" and as such is only able to access files in directories that have ACLs granting system:anyuser access.
783 Many systems have the klog function built into the system login program. So a user would not even have to know they gain a token on logging in. If you use a system where you have to issue the klog command after login then you should run the pagsh command first (see below).
785 AFS provides access control lists to give more precise control to users wishing to protect their files (see AFS ACL below).
787 **File permissions:** [ User ]
789 Unix mode bits for group and other are ignored. The mode bits for the file owner don't work the way they used to.
791 Users should protect their AFS files with (directory) ACLs only. Just use mode bits to make a file executable.
793 **Data protection with AFS ACLs:** [ User ]
795 Some versions of unix (eg IBM's AIX version 3) allow ACLs on local files. In AFS, ACLs protect directories and used with AFS protection groups (see below) provide a finer granularity of protection than can be achieved with basic unix file permissions. (AFS ACLs are described in more detail below.)
797 **Protection groups:** [ User ]
799 Users can create and maintain their own protection groups in AFS - as opposed to unix where only sys admins can manage protection groups.
801 **Hard links:** [ User ]
803 In AFS, hard links (eg: ln old new) are only valid within a directory. This is because AFS ACLs protect directories (not individual files) and allowing hard links that span directories would subvert ACL protection.
805 Symbolic links work in AFS because they reference a pathname and not an i-node directly. (Hard links reference an i-node directly.)
807 **Changing file protection by moving a file:** [ User ]
809 Moving a file to a different directory will change the protection of a file if the ACL on the new directory if different to the ACL on the original directory.
811 **chown and chgrp:** [ User ]
813 Only members of the AFS group "system:administrators" can use these commands on files in /afs.
815 **Save on close:** [ Programmer ]
817 AFS Cache Manager does not send file modifications to a file server until the close() or fsync() system call.
819 write() system calls only update the local cache copy on the client.
821 Note the difference in semantic of writing a file:
823 <table border="1" cellpadding="0" cellspacing="0">
825 <th bgcolor="#99CCCC"><strong> local unix file: </strong></th>
826 <td> writes update the file "immediately" </td>
829 <th align="center" bgcolor="#99CCCC"><strong> AFS file: </strong></th>
830 <td> local cached copy updated "immediately" but the server copy is only updated when the file is closed or fsync'ed. </td>
834 It is important to understand that most applications (eg: vi, emacs, frame, interleaf, wingz, dogz, etc) issue the close() system call when the user chooses/issues the "save" command in the application.
836 Users are not required to exit the application to "save" their changes back to the server.
838 **byte-range file locking:** [ Programmer ]
840 AFS does not support byte-range locking within a file, although lockf() and fcntl() calls will return 0 (success). The first time a byte-range lock is attempted, AFS will display:
842 "afs: byte-range lock/unlock ignored; make sure no one else else is running this program."
844 **whole file locking:** [ Programmer ]
846 AFS does support advisory locking an entire file with flock(). Processes on the same client workstation that attempt to lock a file obey the proper locking semantics.
848 Processes on different AFS clients requesting a lock on the same file would get EWOULDBLOCK returned.
850 **character and block special files:** [ [[SysAdmin]] ]
852 AFS does not support character and block special files. The mknod command does not create either character or block special files in /afs.
854 **AFS version of fsck:** [ [[SysAdmin]] ]
856 On an AFS server, the partitions containing served files are NOT unix filesystems and standard fsck **must** not be used - use the AFS version instead.
858 ### <a name="2.02 What is an AFS protection"></a><a name="2.02 What is an AFS protection "></a> 2.02 What is an AFS protection group?
860 A named list of users.
862 Group names are used in AFS ACLs to identify lists of users with particular access permissions.
864 In AFS, users can create and maintain their own protection groups. This is different to unix where only the system administrator can manage /etc/group.
866 AFS groups are stored in the protection database on fileserver(s) and managed by using the "pts" command.
868 An AFS group typically has the format:
870 - owner-id:group-name
872 By default, only the owner of a group can change its members.
874 It is possible to have both users and IP addresses as members of an AFS group. By using an IP address like this you can specify all the users from the host with that IP address.
876 ### <a name="2.03 What are the AFS defined p"></a> 2.03 What are the AFS defined protection groups?
879 - Everyone who has access to an AFS client in any cell that is on the same network as your cell.
882 - Everyone who has access to an AFS client in any cell that is on the same network as your cell **and** has valid tokens for your cell (ie has been authenticated in your cell).
884 - system:administrators
885 - Users who have privileges to execute some but not all system administrator commands.
887 ### <a name="2.04 What is an AFS access cont"></a> 2.04 What is an AFS access control list (ACL)?
889 There is an ACL for every directory in AFS. The ACL specifies protection at the directory level (not file level) by listing permissions of users and/or groups to a directory. There is a maximum of 20 entries on an ACL.
893 An AFS ACL is displayed by using the "fs" command as shown below:
895 tweety@toontown $ fs listacl .
901 This ACL shows that members of the AFS protection group "fac:coords" have full access rights to the current directory and "system:anyuser" has only read and lookup rights.
903 The members of "fac:coords" can be determined by accessing the protection group database using the "pts" command as shown below:
905 tweety@toontown $ pts membership fac:coords
906 Members of fac:coords (id: -1577) are:
911 ### <a name="2.05 What are the AFS access ri"></a> 2.05 What are the AFS access rights?
913 In AFS, there are seven access rights that may be set or not set:
915 <table border="1" cellpadding="0" cellspacing="0">
917 <th bgcolor="#99CCCC"><strong> lookup </strong></th>
918 <td><code>l</code></td>
919 <td> Permission to examine the ACL and traverse the directory (needed with most other access rights). Permission to look up filenames in a directory. </td>
922 <th bgcolor="#99CCCC"><strong> read </strong></th>
923 <td><code>r</code></td>
924 <td> View the contents of files in the directory </td>
927 <th bgcolor="#99CCCC"><strong> insert </strong></th>
928 <td><code>i</code></td>
929 <td> Add new files or sub-directories </td>
932 <th bgcolor="#99CCCC"><strong> write </strong></th>
933 <td><code>w</code></td>
934 <td> Modify file contents, use "chmod" </td>
937 <th bgcolor="#99CCCC"><strong> delete </strong></th>
938 <td><code>d</code></td>
939 <td> Remove file(s) in directory </td>
942 <th bgcolor="#99CCCC"><strong> lock </strong></th>
943 <td><code>k</code></td>
944 <td> Permission for programs to "flock" files in the directory </td>
947 <th bgcolor="#99CCCC"><strong> administer </strong></th>
948 <td><code>a</code></td>
949 <td> Ability to change the ACL </td>
953 There are short-hand forms:
955 <table border="1" cellpadding="0" cellspacing="0">
957 <th bgcolor="#99CCCC"><strong> read </strong></th>
958 <td><code>rl</code></td>
959 <td> read and lookup </td>
962 <th bgcolor="#99CCCC"><strong> write </strong></th>
963 <td><code>rlidwk</code></td>
964 <td> all rights except administer </td>
967 <th bgcolor="#99CCCC"><strong> all </strong></th>
968 <td><code>rlidwka</code></td>
969 <td> all rights </td>
972 <th bgcolor="#99CCCC"><strong> none </strong></th>
974 <td> removes all rights </td>
978 ### <a name="2.06 What is pagsh?"></a> 2.06 What is pagsh?
980 A command to get a new shell with a process authentication group (PAG).
982 This is normally used if your system does not use the AFS version of login. It is used to get a PAG prior to running klog.
984 The PAG uniquely identifies the user to the Cache Manager. Without a PAG the Cache Manager uses the unix UID to identify a user.
986 ### <a name="2.07 Why use a PAG?"></a> 2.07 Why use a PAG?
988 There are two reasons:
990 1. Child processes inherit the PAG and the Kerberos token so they are AFS authenticated.
992 1. For security: if you don't have a PAG then the Cache Manager identifies you by unix UID. Another user with root access to the client could su to you and therefore use your token.
994 ### <a name="2.08 How can I tell if I have a"></a> 2.08 How can I tell if I have a PAG?
996 You can tell if you have a PAG by typing "groups". A PAG is indicated by the appearance of two integers in the list of groups.
1000 sylvester@toontown $ groups
1001 33536 32533 staff catz
1003 ### <a name="2.09 Can I still run cron jobs"></a><a name="2.09 Can I still run cron jobs "></a> 2.09 Can I still run cron jobs with AFS?
1005 Yes, but remember that in order to fully access files in AFS you have to be AFS authenticated. If your cron job doesn't klog then it only gets system:anyuser access.
1007 The klog command has a "-pipe" option which will read a password from stdin. IF (yes, that's a big if :-) you are prepared to store your password in a local (non-AFS) file then you might use the following:
1009 (a) create a "wrapper" script to get a PAG, get your AFS token and execute a command:
1011 #!/usr/afsws/bin/pagsh
1013 # NAME afs_wrap_cron
1014 # AUTHOR Paul Blackburn <mpb@acm.org>
1015 # PURPOSE Run an AFS authenticated cron job.
1016 # Get a PAG, get the user's token,
1017 # then exec user's command
1022 echo "Usage: ${CMD} [ -principal AFSID ] passwordfile command" >&2
1025 if [ ${1} = "-principal" ]; then
1026 PRINCIPAL="${1} ${2}"
1030 if [ -z "${1}" ]; then
1031 echo "${CMD} error: need name of password file" >&2
1039 /usr/afsws/bin/klog ${PRINCIPAL} -pipe < ${passwordfile}
1041 if [ -z "${1}" ]; then
1042 echo "${CMD} error: need name of command to run" >&2
1047 command=`echo ${command_line} | awk '{print $1}'`
1049 # Check if we can run the command.
1050 # If we got this far, it is likely that the command name is correct
1051 # but there may be a problem in accessing the command file.
1052 # If there is an error, log it via syslog (logger) rather than ">&2"
1054 if [ ! -x "${command}" ]; then
1055 M="error: unable to execute command ${command}"
1056 logger -i -t "${CMD}" "${M}"
1060 exec ${command_line}
1062 (b) Store your password in a local (non-AFS) file that only you have access to (perhaps: /home/$USER/.p).
1064 Make sure that this file is mode 600 and also be sure that you trust whoever has root access on this system and whoever has access to backup tapes! Also, don't forget to change this file if you change your AFS password.
1066 (c) In your crontab file, run afs\_wrap\_cron followed by unlog:
1068 0 6 * * * /usr/local/bin/afs_wrap_cron /home/$USER/.p \
1069 $HOME/bin/6AMdaily; /usr/afsws/bin/unlog
1071 Note that you can still run a cron job without getting a token if the task does not need to be AFS authenticated. In this case, you may get stderr from the cron job if your .profile is not accessible because of the ACL protecting your $HOME. Simply redirect to /dev/null:
1073 0 7 * * * $sys_anyuser_readable_dir/7AMdaily 2>/dev/null
1075 ### <a name="2.10 How much disk space does a"></a> 2.10 How much disk space does a 1 byte file occupy in AFS?
1079 Other filesystems allocate different file block sizes. For example, IBM's AIX version 3 journaled file system (JFS) uses 4K blocks (exception: 2K for the 160MB disk drive).
1081 Such blocksize differences lead to variations on the amount of disk space required to store files. Copying a directory from AFS to AIX JFS would require more space in JFS because of the block fragmentation.
1085 (a) Create a one byte file in AFS and use "ls -s" to show how many kilobytes it occupies:
1087 ariel@atlantica $ echo z >/afs/dsea/tmp/one_byte_file
1088 ariel@atlantica $ ls -s /afs/dsea/tmp/one_byte_file
1089 1 /afs/dsea/tmp/one_byte_file
1091 (b) Create same file in local filesystem (AIX JFS):
1093 ariel@atlantica $ echo z >/tmp/one_byte_file
1094 ariel@atlantica $ ls -s /tmp/one_byte_file
1095 4 /tmp/one_byte_file
1097 ### <a name="2.11 Is it possible to specify"></a><a name="2.11 Is it possible to specify "></a> 2.11 Is it possible to specify a user who is external to the current AFS cell on an ACL?
1099 No. You cannot reference a particular user from another AFS cell.
1101 You can specify an IP address on the ACL; this means any and all users from the host with that IP address.
1103 Another solution to this problem is to give the external user an "authentication-only" account in your AFS cell. This means that (s)he can klog (but has no home directory) in your cell.
1105 # Example: AFS administrator creates an authentication-only user
1106 $ uss add daffy "Daffy Duck" -t /dev/null
1107 $ kas setpassword daffy -admin admin
1109 Cross-realm authentication (where co-operating cells are able to specify remore users as "user@remote.cell" on an ACL) is an **unsupported** feature of AFS 3.3a. That means that Transarc doesn't promise to make it work for you, nor keep it running in future releases.
1111 ### <a name="2.12 Are there any problems pri"></a> 2.12 Are there any problems printing files in /afs?
1113 The issue of printing in AFS is almost always the same: what do you send to the printing daemon? Do you send it the bytes you want to print or do you just send the file name containing those bytes? If you send it a file name, you have to be sure that the printing daemon can read it. Most daemons run with no AFS tokens, so can't access directories unless they are open for system:anyuser read access. Often, printing commands (lpr, lp, enq) have an option that allows for both modes of operation, though the default behavior varies from system to system. If you're interested in making your daemons authenticate to AFS, check out the example scripts in AFS-Contrib:
1115 - <file:///afs/transarc.com/public/afs-contrib/tools/reauth-example>
1116 - <ftp://ftp.transarc.com/pub/afs-contrib/tools/reauth-example/>
1118 Another common problem is setuid printing commands. For instance, the "enq" command runs as root, daemon, or some such user. If you aren't using the AFS login and simply issue "klog" to get tokens, those tokens are associated with your uid. When setuid programs run, they lose access to your token and often can't read the file name given as an argument. The solution in this case is to use "pagsh" before "klog" so that your tokens are transferred to subprocesses automatically by group membership. This works even if the uid changes, as for setuid programs.
1120 ### <a name="2.13 Can I create a fifo (aka n"></a> 2.13 Can I create a fifo (aka named pipe) in /afs?
1122 No. AFS does not support "mknod fifofile p".
1124 ### <a name="2.14 If an AFS server crashes,"></a><a name="2.14 If an AFS server crashes, "></a> 2.14 If an AFS server crashes, do I have to reboot my AFS client?
1128 Typically, if an AFS server becomes unavailable, the AFS Cache Manager on your AFS client will see you through the outage until the server returns. This robustness is dependent on the way your AFS cell has been configured including the following factors:
1130 - On the client side:
1131 - How big is the cache?
1132 - Are the files you need already in the cache?
1134 - On the server side:
1135 - How many servers? It's best to have a minimum of three.
1136 - Is the data you are accessing replicated? In AFS, replicas are [[ReadOnly]] copies.
1138 With replicated volumes, the AFS Cache Manager knows about all of the servers on which the replicas are located. Therefore, when the Cache Manager accesses a replicated volume, if the RPC times out, the Cache Manager automatically retrys the RPC, using a different file server.
1140 If necessary, the Cache Manager will attempt to contact all file servers on which a replica of the volume resides.
1142 If you are accessing [[ReadWrite]] volumes on a crashed server then you will not be able to save changes back to the server until it returns.
1144 You don't need to reboot, and the Cache Manager activity is "invisible" to the user.
1146 ### <a name="2.15 Can I use AFS on my diskle"></a> 2.15 Can I use AFS on my diskless workstation?
1148 Yes. The AFS Cache Manager can be configured to work with either a disk based cache or a memory (RAM) based cache. With the latter, you can expect file access from the cache with a whizz!
1150 <http://www.uni-hohenheim.de/~schaefer/afs/info-afs/1306.html>
1152 ### <a name="2.16 Can I test for AFS tokens"></a><a name="2.16 Can I test for AFS tokens "></a> 2.16 Can I test for AFS tokens from within my program?
1154 Yes. Some sample code showing how to do this can be found in:
1156 <file:///afs/transarc.com/public/afs-contrib/tools/auth-samples/listtokens.c> <ftp://ftp.transarc.com/pub/afs-contrib/tools/auth-samples/listtokens.c>
1158 +++ 2.17 What's the difference between /afs/cellname and /afs/.cellname?
1160 AFS has [[ReadOnly]] (RO) and [[ReadWrite]] (RW) volumes.
1162 The convention in AFS is to mount the RW volume "root.cell" as /afs/.cellname and the RO volume "root.cell.readonly" as /afs/cellname.
1164 This is so that when you travel down the /afs/.cellname link, AFS will always use the RW site of any volumes that have RO clones.
1166 This allows your administrator to update the RW copy of a volume and "vos release $volname" so that it will appear in /afs/cellname.
1168 ### <a name="2.18 Can I klog as two users on"></a> 2.18 Can I klog as two users on a machine in the same cell?
1170 Yes, if you use two different PAGs.
1172 It's: "One token per PAG per client system."
1174 From one shell you can only authenticate as a single user of a cell. If you open another shell (with another PAG) you can klog as a different user of the same cell from the same client.
1176 You can authenticate into many cells from one client shell.
1178 ### <a name="2.19 What are the ~/._afsXXXX f"></a> 2.19 What are the ~/.\_\_afsXXXX files?
1180 They are temporary reference files used by the AFS Cache Manager.
1182 In UNIX filesystems, when you a remove a file that is kept open by a process, the file stays around physically while it is no longer referenced in any directory (which you will see as a mismatch between disk space usage according to df and du).
1184 Some applications rely on that feature, e.g. they create a temporary file and remove it immediatley while keeping the file descriptor open. The file then disappears from the filesystem automagically when the process terminates or the file descriptor gets closed otherwise. Such applications could get into trouble with older versions of AFS, where the file could really disappear while it was held open.
1186 Newer versions of AFS rename such files to .\_\_afsXXXX, thus making sure that the data stays around as expected by the application. As soon as the file gets closed, the associated .\_\_afsXXXX should disappear.
1188 ## <a name="3 AFS administration"></a> 3 AFS administration
1190 ### <a name="3.01 Is there a version of xdm"></a><a name="3.01 Is there a version of xdm "></a> 3.01 Is there a version of xdm available with AFS authentication?
1192 Yes, xdm can be found in:
1194 <file:///afs/transarc.com/public/afs-contrib/tools/xdm> <ftp://ftp.transarc.com/pub/afs-contrib/tools/xdm/>
1196 ### <a name="3.02 Is there a version of xloc"></a> 3.02 Is there a version of xlock available with AFS authentication?
1198 Yes, xlock can be found in:
1200 <file:///afs/transarc.com/public/afs-contrib/tools/xlock> <ftp://ftp.transarc.com/pub/afs-contrib/tools/xlock/>
1202 ### <a name="3.03 What is /afs/@cell?"></a> 3.03 What is /afs/@cell?
1204 It is a symbolic link pointing at /afs/$your\_cell\_name.
1206 NB, @cell is not something that is provided by AFS. You may decide it is useful in your cell and wish to create it yourself.
1208 /afs/@cell is useful because:
1210 - If you look after more than one AFS cell, you could create the link in each cell then set your PATH as:
1211 - PATH=$PATH:/afs/@cell/@sys/local/bin
1213 - For most cells, it shortens the path names to be typed in thus reducing typos and saving time.
1215 A disadvantage of using this convention is that when you cd into /afs/@cell then type "pwd" you see "/afs/@cell" instead of the full name of your cell. This may appear confusing if a user wants to tell a user in another cell the pathname to a file.
1217 You could create your own /afs/@cell with the following:
1221 [ -L /afs/@cell ] && echo We already have @cell! && exit
1222 cell=$(cat /usr/vice/etc/ThisCell)
1223 cd /afs/.${cell} && fs mkm temp root.afs
1225 ln -s /afs/${cell} @cell
1226 ln -s /afs/.${cell} .@cell # .@cell for RW path
1227 cd /afs/.${cell} && fs rmm temp
1228 vos release root.afs; fs checkv
1230 <http://www-archive.stanford.edu/lists/info-afs/hyper95/0298.html>
1232 ### <a name="3.04 Given that AFS data is loc"></a> 3.04 Given that AFS data is location independent, how does an AFS client determine which server houses the data its user is attempting to access?
1234 The Volume Location Database (VLDB) is stored on AFS Database Servers and is ideally replicated across 3 or more Database Server machines. Replication of the Database ensures high availability and load balances the requests for the data. The VLDB maintains information regarding the current physical location of all volume data (files and directories) in the cell, including the IP address of the [[FileServer]], and the name of the disk partition the data is stored on.
1236 A list of a cell's Database Servers is stored on the local disk of each AFS Client machine as: /usr/vice/etc/CellServDB
1238 The Database Servers also house the Kerberos Authentication Database (encrypted user and server passwords), the Protection Database (user UID and protection group information) and the Backup Database (used by System Administrators to backup AFS file data to tape).
1240 ### <a name="3.05 Which protocols does AFS u"></a> 3.05 Which protocols does AFS use?
1242 AFS may be thought of as a collection of protocols and software processes, nested one on top of the other. The constant interaction between and within these levels makes AFS a very sophisticated software system.
1244 At the lowest level is the UDP protocol, which is part of TCP/IP. UDP is the connection to the actual network wire. The next protocol level is the remote procedure call (RPC). In general, RPCs allow the developer to build applications using the client/server model, hiding the underlying networking mechanisms. AFS uses Rx, an RPC protocol developed specifically for AFS during its development phase at Carnegie Mellon University.
1246 Above the RPC is a series of server processes and interfaces that all use Rx for communication between machines. Fileserver, volserver, upserver, upclient, and bosserver are server processes that export RPC interfaces to allow their user interface commands to request actions and get information. For example, a bos status command will examine the bos server process on the indicated file server machine.
1248 Database servers use ubik, a replicated database mechanism which is implemented using RPC. Ubik guarantees that the copies of AFS databases of multiple server machines remain consistent. It provides an application programming interface (API) for database reads and writes, and uses RPCs to keep the database synchronized. The database server processes, vlserver, kaserver, and ptserver, reside above ubik. These processes export an RPC interface which allows user commands to control their operation. For instance, the pts command is used to communicate with the ptserver, while the command klog uses the kaserver's RPC interface.
1250 Some application programs are quite complex, and draw on RPC interfaces for communication with an assortment of processes. Scout utilizes the RPC interface to file server processes to display and monitor the status of file servers. The uss command interfaces with kaserver, ptserver, volserver and vlserver to create new user accounts.
1252 The Cache Manager also exports an RPC interface. This interface is used principally by file server machines to break callbacks. It can also be used to obtain Cache Manager status information. The program cmdebug shows the status of a Cache Manager using this interface.
1254 For additional information, Section 1.5 of the AFS System Administrator's Guide and the April 1990 Cache Update contain more information on ubik. Udebug information and short descriptions of all debugging tools were included in the January 1991 Cache Update. Future issues will discuss other debugging tools in more detail.
1256 [ source: <ftp://ftp.transarc.com/pub/afsug/newsletter/apr91> ] [ Copyright 1991 Transarc Corporation ]
1258 ### <a name="3.06 Are setuid programs execut"></a> 3.06 Are setuid programs executable across AFS cell boundaries?
1260 By default, the setuid bit is ignored but the program may be run (without setuid privilege).
1262 It is possible to configure an AFS client to honour the setuid bit. This is achieved by root running:
1264 root@toontown # fs setcell -cell $cellname -suid
1266 (where $cellname is the name of the foreign cell. Use with care!).
1268 NB: making a program setuid (or setgid) in AFS does **not** mean that the program will get AFS permissions of a user or group. To become AFS authenticated, you have to klog. If you are not authenticated, AFS treats you as "system:anyuser".
1270 ### <a name="3.07 How does AFS maintain cons"></a> 3.07 How does AFS maintain consistency on read-write files?
1272 AFS uses a mechanism called "callback".
1274 Callback is a promise from the fileserver that the cache version of a file/directory is up-to-date. It is established by the fileserver with the caching of a file.
1276 When a file is modified the fileserver breaks the callback. When the user accesses the file again the Cache Manager fetches a new copy if the callback has been broken.
1278 The following paragraphs describe AFS callback mechanism in more detail:
1280 If I open() fileA and start reading, and you then open() fileA, write() a change **\*\*and close() or fsync()\*\*** the file to get your changes back to the server - at the time the server accepts and writes your changes to the appropriate location on the server disk, the server also breaks callbacks to all clients to which it issued a copy of fileA.
1282 So my client receives a message to break the callback on fileA, which it dutifully does. But my application (editor, spreadsheet, whatever I'm using to read fileA) is still running, and doesn't really care that the callback has been broken.
1284 When something causes the application to read() more of the file the read() system call executes AFS cache manager code via the VFS switch, which does check the callback and therefore gets new copies of the data.
1286 Of course, the application may not re-read data that it has already read, but that would also be the case if you were both using the same host. So, for both AFS and local files, I may not see your changes.
1288 Now if I exit the application and start it again, or if the application does another open() on the file, then I will see the changes you've made.
1290 This information tends to cause tremendous heartache and discontent - but unnecessarily so. People imagine rampant synchronization problems. In practice this rarely happens and in those rare instances, the data in question is typically not critical enough to cause real problems or crashing and burning of applications. Since 1985, we've found that the synchronization algorithm has been more than adequate in practice - but people still like to worry!
1292 The source of worry is that, if I make changes to a file from my workstation, your workstation is not guaranteed to be notified until I close or fsync the file, at which point AFS guarantees that your workstation will be notified. This is a significant departure from NFS, in which no guarantees are provided.
1294 Partially because of the worry factor and largely because of Posix, this will change in DFS. DFS synchronization semantics are identical to local file system synchronization.
1296 [ DFS is the Distributed File System which is part of the Distributed ] [ Computing Environment (DCE). ]
1298 ### <a name="3.08 How can I run daemons with"></a> 3.08 How can I run daemons with tokens that do not expire?
1300 It is not a good idea to run with tokens that do not expire because this would weaken one of the security features of Kerberos.
1302 A better approach is to re-authenticate just before the token expires.
1304 There are two examples of this that have been contributed to afs-contrib. The first is "reauth":
1306 <file:///afs/transarc.com/public/afs-contrib/tools/reauth/> <ftp://ftp.transarc.com/pub/afs-contrib/tools/reauth/>
1308 The second is "lat":
1310 /afs/transarc.com/public/afs-contrib/pointers/UMich-lat-authenticated-batch-jobs <ftp://ftp.transarc.com/pub/afs-contrib/pointers/UMich-lat-authenticated-batch-jobs>
1312 +++ 3.09 Can I check my user's passwords for security purposes?
1314 Yes. Alec Muffett's Crack tool (at version 4.1f) has been converted to work on the Transarc kaserver database. This modified Crack (AFS Crack) is available via anonymous ftp from:
1316 - <ftp://export.acs.cmu.edu/pub/crack.tar.Z>
1318 and is known to work on: pmax\_\* sun4\*\_\* hp700\_\* rs\_aix\* next\_\*
1320 It uses the file /usr/afs/db/kaserver.DB0, which is the database on the kaserver machine that contains the encrypted passwords. As a bonus, AFS Crack is usually two to three orders of magnitude faster than the standard Crack since there is no concept of salting in a Kerberos database.
1322 On a normal UNIX /etc/passwd file, each password can have been encrypted around 4096 (2^12) different saltings of the crypt(3) algorithm, so for a large number of users it is easy to see that a potentially large (up to 4095) number of seperate encryptions of each word checked has been avoided.
1324 Author: Dan Lovinger Contact: Derrick J. Brashear <shadow+@andrew.cmu.edu>
1326 <table border="1" cellpadding="0" cellspacing="0">
1329 <td> AFS Crack does not work for MIT Kerberos Databases. The author is willing to give general guidance to someone interested in doing the (probably minimal) amount of work to port it to do MIT Kerberos. The author does not have access to a MIT Kerberos server to do this. </td>
1333 ### <a name="3.10 Is there a way to automati"></a> 3.10 Is there a way to automatically balance disk usage across fileservers?
1335 Yes. There is a tool, balance, which does exactly this. It can be retrieved via anonymous ftp from:
1337 - <ftp://ftp.andrew.cmu.edu/pub/balance-1.1a.tar.Z>
1339 Actually, it is possible to write arbitrary balancing algorithms for this tool. The default set of "agents" provided for the current version of balance balance by usage, # of volumes, and activity per week, the latter currently requiring a source patch to the AFS volserver. Balance is highly configurable.
1341 Author: Dan Lovinger Contact: Derrick Brashear <shadow+@andrew.cmu.edu>
1343 ### <a name="3.11 Can I shutdown an AFS file"></a> 3.11 Can I shutdown an AFS fileserver without affecting users?
1345 Yes, this is an example of the flexibility you have in managing AFS.
1347 Before attempting to shutdown an AFS fileserver you have to make some arrangements that any services that were being provided are moved to another AFS fileserver:
1349 1. Move all AFS volumes to another fileserver. (Check you have the space!) This can be done "live" while users are actively using files in those volumes with no detrimental effects.
1351 1. Make sure that critical services have been replicated on one (or more) other fileserver(s). Such services include:
1352 - kaserver - Kerberos Authentication server
1353 - vlserver - Volume Location server
1354 - ptserver - Protection server
1355 - buserver - Backup server
1357 It is simple to test this before the real shutdown by issuing:
1359 bos shutdown $server $service
1361 where: $server is the name of the server to be shutdown
1362 and $service is one (or all) of: kaserver vlserver ptserver buserver
1364 Other points to bear in mind:
1366 - "vos remove" any RO volumes on the server to be shutdown. Create corresponding RO volumes on the 2nd fileserver after moving the RW. There are two reasons for this:
1367 1. An RO on the same partition ("cheap replica") requires less space than a full-copy RO.
1368 2. Because AFS always accesses RO volumes in preference to RW, traffic will be directed to the RO and therefore quiesce the load on the fileserver to be shutdown.
1370 - If the system to be shutdown has the lowest IP address there may be a brief delay in authenticating because of timeout experienced before contacting a second kaserver.
1372 ### <a name="3.12 How can I set up mail deli"></a> 3.12 How can I set up mail delivery to users with $HOMEs in AFS?
1374 There are many ways to do this. Here, only two methods are considered:
1376 Method 1: deliver into local filestore
1378 This is the simplest to implement. Set up your mail delivery to append mail to /var/spool/mail/$USER on one mailserver host. The mailserver is an AFS client so users draw their mail out of local filestore into their AFS $HOME (eg: inc).
1380 Note that if you expect your (AFS unauthenticated) mail delivery program to be able to process .forward files in AFS $HOMEs then you need to add "system:anyuser rl" to each $HOMEs ACL.
1384 - Simple to implement and maintain.
1385 - No need to authenticate into AFS.
1389 - It doesn't scale very well.
1390 - Users have to login to the mailserver to access their new mail.
1391 - Probably less secure than having your mailbox in AFS.
1392 - System administrator has to manage space in /var/spool/mail.
1394 Method 2: deliver into AFS
1396 This takes a little more setting up than the first method.
1398 First, you must have your mail delivery daemon AFS authenticated (probably as "postman"). The reauth example in afs-contrib shows how a daemon can renew its token. You will also need to setup the daemon startup soon after boot time to klog (see the -pipe option).
1400 Second, you need to set up the ACLs so that "postman" has lookup rights down to the user's $HOME and "lik" on $HOME/Mail.
1404 - Scales better than first method.
1405 - Delivers to user's $HOME in AFS giving location independence.
1406 - Probably more secure than first method.
1407 - User responsible for space used by mail.
1411 - More complicated to set up.
1412 - Need to correctly set ACLs down to $HOME/Mail for every user.
1413 - Probably need to store postman's password in a file so that the mail delivery daemon can klog after boot time. This may be OK if the daemon runs on a relatively secure host.
1415 An example of how to do this for IBM RISC System/6000 is auth-sendmail. A beta test version of auth-sendmail can be found in:
1417 <file:///afs/transarc.com/public/afs-contrib/doc/faq/auth-sendmail.tar.Z> <ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/auth-sendmail.tar.Z>
1419 ### <a name="3.13 Should I replicate a _Read"></a> 3.13 Should I replicate a [[ReadOnly]] volume on the same partition and server as the [[ReadWrite]] volume?
1421 Yes, Absolutely! It improves the robustness of your served volumes.
1423 If [[ReadOnly]] volumes exist (note use of term **exist** rather than **are available**), Cache Managers will **never** utilize the [[ReadWrite]] version of the volume. The only way to access the RW volume is via the "dot" path (or by special mounting).
1425 This means if **all** RO copies are on dead servers, are offline, are behind a network partition, etc, then clients will not be able to get the data, even if the RW version of the volume is healthy, on a healthy server and in a healthy network.
1427 However, you are **very** strongly encouraged to keep one RO copy of a volume on the **same server and partition** as the RW. There are two reasons for this:
1429 1. The RO that is on the same server and partition as the RW is a clone (just a copy of the header - not a full copy of each file). It therefore is very small, but provides access to the same set of files that all other (full copy) [[ReadOnly]] volume do. Transarc trainers refer to this as the "cheap replica".
1430 2. To prevent the frustration that occurs when all your ROs are unavailable but a perfectly healthy RW was accessible but not used.
1432 If you keep a "cheap replica", then by definition, if the RW is available, one of the RO's is also available, and clients will utilize that site.
1434 ### <a name="3.14 Should I start AFS before"></a><a name="3.14 Should I start AFS before "></a> 3.14 Should I start AFS before NFS in /etc/inittab?
1436 Yes, it is possible to run both AFS and NFS on the same system but you should start AFS first.
1438 In IBM's AIX 3.2, your /etc/inittab would contain:
1440 rcafs:2:wait:/etc/rc.afs > /dev/console 2>&1 # Start AFS daemons
1441 rcnfs:2:wait:/etc/rc.nfs > /dev/console 2>&1 # Start NFS daemons
1443 With AIX, you need to load NFS kernel extensions before the AFS KEs in /etc/rc.afs like this:
1446 # example /etc/rc.afs for an AFS fileserver running AIX 3.2
1448 echo "Installing NFS kernel extensions (for AFS+NFS)"
1449 /etc/gfsinstall -a /usr/lib/drivers/nfs.ext
1450 echo "Installing AFS kernel extensions..."
1451 D=/usr/afs/bin/dkload
1452 ${D}/cfgexport -a ${D}/export.ext
1453 ${D}/cfgafs -a ${D}/afs.ext
1454 /usr/afs/bin/bosserver &
1456 ### <a name="3.15 Will AFS run on a multi-ho"></a> 3.15 Will AFS run on a multi-homed fileserver?
1458 (multi-homed = host has more than one network interface.)
1460 Yes, it will. However, AFS was designed for hosts with a single IP address. There can be problems if you have one host name being resolved to several IP addresses.
1462 Transarc suggest designating unique hostnames for each network interface. For example, a host called "spot" has two tokenring and one ethernet interfaces: spot-tr0, spot-tr1, spot-en0. Then, select which interface will be used for AFS and use that hostname in the [[CellServDB]] file (eg: spot-tr0).
1464 You also have to remember to use the AFS interface name with any AFS commands that require a server name (eg: vos listvol spot-tr0).
1466 There is a more detailed discussion of this in the August 1993 issue of "Cache Update" (see: <ftp://ftp.transarc.com/pub/afsug/newsletter/aug93>).
1468 The simplest way of dealing with this is to make your AFS fileservers single-homed (eg only use one network interface).
1470 At release 3.4 of AFS, it is possible to have multi-homed fileservers (but _not_ multi-homed database servers).
1472 ### <a name="3.16 Can I replicate my user's"></a><a name="3.16 Can I replicate my user's "></a> 3.16 Can I replicate my user's home directory AFS volumes?
1476 Users with $HOMEs in /afs normally have an AFS [[ReadWrite]] volume mounted in their home directory.
1478 You can replicate a RW volume but only as a [[ReadOnly]] volume and there can only be one instance of a [[ReadWrite]] volume.
1480 In theory, you could have RO copies of a user's RW volume on a second server but in practice this won't work for the following reasons:
1482 a) AFS has built-in bias to always access the RO copy of a RW volume.
1483 So the user would have a ReadOnly $HOME which is not too useful!
1485 b) Even if a) was not true you would have to arrange frequent
1486 synchronisation of the RO copy with the RW volume (for example:
1487 "vos release user.fred; fs checkv") and this would have to be
1488 done for all such user volumes.
1490 c) Presumably, the idea of replicating is to recover the $HOME
1491 in the event of a server crash. Even if a) and b) were not
1492 problems consider what you might have to do to recover a $HOME:
1494 1) Create a new RW volume for the user on the second server
1495 (perhaps named "user.fred.2").
1497 2) Now, where do you mount it?
1499 The existing mountpoint cannot be used because it already has
1500 the ReadOnly copy of the original volume mounted there.
1502 Let's choose: /afs/MyCell/user/fred.2
1504 3) Copy data from the RO of the original into the new RW volume
1507 4) Change the user's entry in the password file for the new $HOME:
1508 /afs/MyCell/user/fred.2
1510 You would have to attempt steps 1 to 4 for every user who had
1511 their RW volume on the crashed server. By the time you had done
1512 all of this, the crashed server would probably have rebooted.
1514 The bottom line is: you cannot replicate $HOMEs across servers.
1516 ### <a name="3.17 Which TCP/IP ports and pro"></a> 3.17 Which TCP/IP ports and protocols do I need to enable in order to operate AFS through my Internet firewall?
1518 Assuming you have already taken care of nameserving, you may wish to use an Internet timeserver for Network Time Protocol [35] [36]:
1522 A list of NTP servers is available via anonymous FTP from:
1524 - <http://www.eecis.udel.edu/~mills/ntp/servers.html>
1526 For further details on NTP see: <http://www.eecis.udel.edu/~ntp/>
1528 For a "minimal" AFS service which does not allow inbound or outbound klog:
1531 cachemanager 7001/udp
1539 (Ports in the 7020-7029 range are used by the AFS backup system, and won't be needed by external clients performing simple file accesses.)
1541 Additionally, for "klog" to work through the firewall you need to allow inbound and outbound UDP on ports >1024 (probably 1024<port<2048 would suffice depending on the number of simultaneous klogs).
1543 See also: <http://www-archive.stanford.edu/lists/info-afs/hyper95/0874.html>
1545 ### <a name="3.18 What is the Andrew Benchma"></a> 3.18 What is the Andrew Benchmark?
1547 "It is a script that operates on a collection of files constituting an application program. The operations are intended to represent typical actions of an average user. The input to the benchmark is a source tree of about 70 files. The files total about 200 KB in size. The benchmark consists of five distinct phases:
1549 I MakeDir - Construct a target subtree that is identical to the
1551 II Copy - Copy every file from the source subtree to the target subtree.
1552 III ScanDir - Traverse the target subtree and examine the status
1553 of every file in it.
1554 IV ReadAll - Scan every byte of every file in the target subtree.
1555 V Make - Complete and link all files in the target subtree."
1557 Source: <file:///afs/transarc.com/public/afs-contrib/doc/benchmark/Andrew.Benchmark.ps> <ftp://ftp.transarc.com/pub/afs-contrib/doc/benchmark/Andrew.Benchmark.ps>
1559 ### <a name="3.19 Is there a version of HP V"></a> 3.19 Is there a version of HP VUE login with AFS authentication?
1561 Yes, the availability of this is described in: <file:///afs/transarc.com/public/afs-contrib/pointers/HP-VUElogin.txt> <ftp://ftp.transarc.com/pub/afs-contrib/pointers/HP-VUElogin.txt>
1563 If you don't have access to the above, please contact Rajeev Pandey of Hewlett Packard whose email address is <rpandey@cv.hp.com>.
1565 ### <a name="3.20 How can I list which clien"></a> 3.20 How can I list which clients have cached files from a server?
1567 By using the following script:
1572 # AUTHOR Rainer Toebbicke <rtb@dxcern.cern.ch>
1574 # PURPOSE Display AFS clients which have grabbed files from a server
1577 echo "Usage: $0 <afs_server 1> ... <afsserver n>"
1581 /usr/afsws/etc/rxdebug -servers $n -allconn
1582 done | grep '^Connection' | \
1583 while read x y z ipaddr rest; do echo $ipaddr; done | sort -u |
1584 while read ipaddr; do
1586 n="`nslookup $ipaddr`"
1594 ### <a name="3.21 Do Backup volumes require"></a><a name="3.21 Do Backup volumes require "></a> 3.21 Do Backup volumes require as much space as [[ReadWrite]] volumes?
1598 The technique used is to create a new volume, where every file in the RW copy is pointed to by the new backup volume. The files don't exist in the BK, only in the RW volume. The backup volume therefore takes up very little space.
1600 If the user now starts modifying data, the old copy must not be destroyed.
1602 There is a Copy-On-Write bit in the vnode - if the fileserver writes to a vnode with the bit on it allocates a new vnode for the data and turns off the COW bit. The BK volume hangs onto the old data, and the RW volume slowly splits itself away over time.
1604 The BK volume is re-synchronised with the RW next time a "vos backupsys" is run.
1606 The space needed for the BK volume is directly related to the size of all files changed in the RW between runs of "vos backupsys".
1608 ### <a name="3.22 Should I run timed on my A"></a> 3.22 Should I run timed on my AFS client?
1612 The AFS Cache Manager makes use of NTP [35] [36] to synchronise time with your cell's NTP servers.
1614 Typically, one of your AFS cell's servers synchronises with an external NTP server and provides accurate time to your cell.
1616 ### <a name="3.23 Why should I keep /usr/vic"></a> 3.23 Why should I keep /usr/vice/etc/CellServDB current?
1618 On AFS clients, /usr/vice/etc/CellservDB, defines the cells and (their servers) that can be accessed via /afs.
1620 Over time, site details change: servers are added/removed or moved onto new network addresses. New sites appear.
1622 In order to keep up-to-date with such changes, the [[CellservDB]] file on each AFS client should be kept consistent with some master copy (at your site).
1624 As well as updating [[CellservDB]], your AFS administrator should ensure that new cells are mounted in your cell's root.afs volume.
1626 ### <a name="3.24 How can I keep /usr/vice/e"></a> 3.24 How can I keep /usr/vice/etc/CellServDB current?
1628 Do a daily copy from a master source and update the AFS kernel sitelist.
1630 The client [[CellServDB]] file must not reside under /afs and is best located in local filespace.
1632 Simply updating a client [[CellServDB]] file is not enough. You also need to update the AFS kernel sitelist by either: 1 rebooting the client or 1 running "fs newcell $cell\_name $server\_list" for each site in the [[CellServDB]] file.
1634 A script to update the AFS kernel sitelist on a running system is newCellServDB.
1636 <file:///afs/ece.cmu.edu/usr/awk/Public/newCellServDB> <ftp://ftp.ece.cmu.edu/pub/afs-tools/newCellServDB>
1638 One way to distribute [[CellServDB]] is to have a root cron job on each AFS client copy the file then run newCellServDB.
1644 # NAME syncCellServDB
1645 # PURPOSE Update local CellServDB file and update AFS kernel sitelist
1646 # USAGE run by daily root cron job eg:
1647 # 0 3 * * * /usr/local/sbin/syncCellServDB
1649 # NOTE "@cell" is a symbolic link to /afs/$this_cell_name
1651 src=/afs/@cell/service/etc/CellServDB
1652 dst=/usr/vice/etc/CellServDB
1653 xec=/usr/local/sbin/newCellServDB
1654 log=/var/log/syncCellServDB
1656 if [ -s ${src} ]; then
1657 if [ ${src} -nt ${dst} ]; then
1658 cp $dst ${dst}- && cp $src $dst && $xec 2>&1 >$log
1660 echo "master copy no newer: no processing to be done" >$log
1663 echo "zero length file: ${src}" >&2
1666 ### <a name="3.25 How can I compute a list o"></a> 3.25 How can I compute a list of AFS fileservers?
1668 Here is a Korn shell command to do it:
1670 stimpy@nick $ vos listvldb -cell $(cat /usr/vice/etc/ThisCell) \
1671 | awk '(/server/) {print $2}' | sort -u
1673 ### <a name="3.26 How can I set up anonymous"></a> 3.26 How can I set up anonymous FTP login to access /afs?
1675 The easiest way on a primarily "normal" machine (where you don't want to have everything in AFS) is to actually mount root.cell under ~ftp, and then symlink /afs to ~ftp/afs or whatever. It's as simple as changing the mountpoint in /usr/vice/etc/cacheinfo and restarting afsd.
1677 Note that when you do this, anon ftp users can go anywhere system:anyuser can (or worse, if you're using IP-based ACLs and the ftp host is PTS groups). The only "polite" solution I've arrived at is to have the ftp host machine run a minimal [[CellServDB]] and police my ACLs tightly.
1679 Alternatively, you can make ~ftp an AFS volume and just mount whatever you need under that - this works well if you can keep everything in AFS, and you don't have the same problems with anonymous "escapes" into /afs.
1681 Unless you need to do authenticating ftp, you are _strongly_ recommended using wu-ftpdv2.4 (or better).
1683 ### <a name="3.27 Where can I find the Andre"></a> 3.27 Where can I find the Andrew Benchmark?
1685 <file:///afs/transarc.com/public/afs-contrib/doc/faq/ab.tar.Z> [156k] <ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/ab.tar.Z> [156k]
1687 This is a tar archive of <file:///afs/cs.cmu.edu/user/satya/ftp/ab/>
1689 ## <a name="4 Getting more information"></a> 4 Getting more information
1691 ### <a name="4.01 Is there an anonymous FTP"></a><a name="4.01 Is there an anonymous FTP "></a> 4.01 Is there an anonymous FTP site with AFS information?
1693 Yes, it is: ftp.transarc.com
1695 A brief summary of contents:
1697 <table border="1" cellpadding="0" cellspacing="0">
1699 <th align="center" bgcolor="#99CCCC"><strong> Directory </strong></th>
1700 <th align="center" bgcolor="#99CCCC"><strong> Contents </strong></th>
1703 <td> pub/afsug/newsletter </td>
1704 <td> AFS user group newsletters </td>
1707 <td> pub/afs-contrib </td>
1708 <td> Contributed tools and documents </td>
1711 <td> pub/afsps/doc </td>
1712 <td> release notes, SUPPORTED_SYSTEMS.afs.* </td>
1715 <td> pub/afsug </td>
1716 <td> AFS user group (see README for detail) </td>
1719 <td> pub/afsps/progint </td>
1720 <td> AFS programming interface docs </td>
1724 These directories are also accessible via AFS. For example: /afs/transarc.com/public/afs-contrib
1726 (NB "pub" => "public" when using AFS to access these.)
1728 ### <a name="4.02 Which USENET newsgroups di"></a> 4.02 Which USENET newsgroups discuss AFS?
1730 alt.filesystems.afs and occasionally in comp.unix.admin.
1732 ### <a name="4.03 Where can I get training i"></a> 4.03 Where can I get training in AFS?
1734 Transarc provide user and administrator courses. These can be provided at the customer site or at Transarc's offices.
1736 Transarc's education coordinator may be contacted by:
1740 <dd> +1 412 338 4363 email: <a href="mailto:education@transarc.com">education@transarc.com</a></dd>
1743 <http://www.transarc.com>
1745 ### <a name="4.04 Where can I find AFS resou"></a> 4.04 Where can I find AFS resources in World Wide Web (WWW)?
1747 Here are some I have found (please let me know if you find more):
1749 a) A collection of AFS information maintained by Derrick Brashear at CMU:
1751 http://www.cs.cmu.edu/afs/andrew.cmu.edu/usr/shadow/www/afs.html
1752 (Also accessible in: /afs/andrew.cmu.edu/usr/shadow/www)
1754 b) AFS Beginners Guide (ALW/NIH):
1755 http://www.alw.nih.gov/Docs/AFS/AFS_toc.html
1757 c) NCSA AFS User Guide:
1758 http://www.ncsa.uiuc.edu/Pubs/UserGuides/AFSGuide/AFSv2.1Book.html
1760 d) Transarc AFS Product Information:
1761 http://www.transarc.com/dfs/public/www/htdocs/.hosts/external/Product/EFS/AFS/afsoverview.html
1763 e) CERN AFS User's Guide:
1764 http://wsspinfo.cern.ch/file/doc/afsug.html
1766 f) MIT SIPB's Inessential AFS
1767 http://web.mit.edu/afs/sipb.mit.edu/project/doc/afs/html/afs-new.html
1769 g) Stanford University hypermail archive of info-afs@transarc.com
1770 http://www-archive.stanford.edu/lists/info-afs.html
1773 http://www.umlug.umd.edu/linuxafs/
1775 ### <a name="4.05 Is there a mailing list fo"></a> 4.05 Is there a mailing list for AFS topics?
1777 Yes, it is <info-afs@transarc.com>.
1779 An automated program called Majordomo is now handling the info-afs list. To join the mailing list, send a message to:
1781 <majordomo@transarc.com>
1783 In the body (not the Subject line) of the message, type:
1789 $ mail -s "subscribe to info-afs" <majordomo@transarc.com> <<% subscribe info-afs %
1793 $ mail -s "unsubscribe from info-afs" <majordomo@transarc.com> <<% unsubscribe info-afs
1795 ### <a name="4.06 Where can I find an archiv"></a> 4.06 Where can I find an archive of <info-afs@transarc.com>?
1797 There is a hypermail archive at: <http://www-archive.stanford.edu/lists/info-afs.html>
1799 ### <a name="4.07 Where can I find an archiv"></a> 4.07 Where can I find an archive of alt.filesystems.afs?
1801 <file:///afs/ibm.uk/common/archive/alt.filesystems.afs/>
1803 Both the <info-afs@transarc.com> and alt.filesystems.afs archives are incomplete. If you have material to contribute, please let me know.
1805 ### <a name="4.08 Where can I find AFS relat"></a> 4.08 Where can I find AFS related GIFs?
1807 <file:///afs/transarc.com/public/afs-contrib/doc/faq/images/index.html> <ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/images/index.html>
1809 ### <a name="4.09 Gibt es eine deutsche AFS"></a><a name="4.09 Gibt es eine deutsche AFS "></a> 4.09 Gibt es eine deutsche AFS Benutzer Gruppe?
1811 Ja, wenn Sie mitmachen wollen, schicken Sie bitte eine E-Mail an:
1813 <afsdeu-request@hrz.th-darmstadt.de>
1815 Ueber diese Adresse werden "subscribe" und "unsubscribe" Requests bearbeitet.
1817 ### <a name="4.10 Donde puedo encontrar info"></a> 4.10 Donde puedo encontrar informacion en Espanol sobre AFS?
1819 Hay algunas notas en Espanol sobre AFS en: <http://w3.ing.puc.cl/~cet/afs.html>
1821 ## <a name="5 About the AFS faq"></a> 5 About the AFS faq
1823 I started compiling the FAQ after attending an AFS administrators class and while waiting for the distribution tape to arrive from Transarc (back in July 93). The initial goal was to assist users at my site to understand AFS issues.
1825 The FAQ seemed to be a more widely useful resource so it was made generally available.
1827 I hope you have found the AFS FAQ useful.
1829 Your criticism or suggestions for improving it are welcome, so please don't hesitate to email your views (or just say "hello").
1831 This compilation is dedicated to my AFS teacher and all those who inspire through good humour, enthusiasm, wit and wisdom. -- paul <http://acm.org/~mpb/homepage.html>
1833 ### <a name="5.01 How can I get a copy of th"></a> 5.01 How can I get a copy of the AFS faq?
1835 If you do make a copy, please be aware that this compilation changes over time: you will need to do a periodic re-copy to keep your copy up-to-date.
1837 There are two reference sources:
1839 1) The text only version, available via AFS from:
1840 /afs/transarc.com/public/afs-contrib/doc/faq/afs.faq
1842 2) The World Wide Web (HTML) version, available via URL:
1843 http://www.angelfire.com/hi/plutonic/afs-faq.html
1845 There are several other ways to get a copy.
1847 via AFS: /afs/transarc.com/public/afs-contrib/doc/faq/afs.faq
1849 via FTP: <ftp://rtfm.mit.edu/pub/usenet/news.answers/afs-faq>
1851 via WWW: <http://www.angelfire.com/hi/plutonic/afs-faq.html>
1855 From time to time this faq will be posted to the USENET newsgroups: alt.filesystems.afs alt.answers news.answers
1859 The AFS faq is now available on CD-ROM "Internet Info" (containing
1861 1. ,420 documents including other FAQs, RFCs, IENs, etc) from:
1863 Walnut Creek CDROM phone: 1 800 786-9907 (US tollfree)
1865 1. 1. Pike Lane, Ste D-www +1 510 674-0783 Concord, CA 94250 fax: +1 510 674-0821 United States of America email: <orders@cdrom.com> WWW: <http://www.cdrom.com/>
1867 The file is in: $cd\_mount\_point/faqs/alt/filesystems.afs
1869 ### <a name="5.02 How can I get my question"></a><a name="5.02 How can I get my question "></a> 5.02 How can I get my question (and answer) into the AFS faq?
1871 Comments and contributions are welcome, please send to: <mpb@acm.org>
1873 I am looking for reviewers to help me check the material here, please let me know if you would like to help.
1875 ### <a name="5.03 How can I access the AFS f"></a> 5.03 How can I access the AFS faq via the World Wide Web?
1877 To access the World Wide Web you either need your own browser or have telnet access to WWW servers.
1879 WWW browsers exist for most machines. Here's a list of some browsers;
1881 Name System/requirements Available from (among others) <code>**== =================**</code> <code>**==========**</code> Mosaic X windows, MS-Windows, Mac ftp.ncsa.uiuc.edu /Web lynx vt100 ftp.wustl.edu /packages/www/lynx
1883 From your own browser, OPEN or GO to the following document:
1885 <http://www.angelfire.com/hi/plutonic/afs-faq.html>
1887 It is much better to run your own browser but if this is not possible there are several WWW servers accessible via telnet:
1889 \* telnet info.cern.ch then type: go <http://www.angelfire.com/hi/plutonic/afs-faq.html>
1891 \* telnet www.njit.edu (login: www) then type: g <http://www.angelfire.com/hi/plutonic/afs-faq.html>
1893 \* telnet ukanaix.cc.ukans.edu (login: www, needs vt100) then type: ghttp://www.angelfire.com/hi/plutonic/afs-faq.html
1895 ## <a name="6 Bibliography"></a> 6 Bibliography
1897 If documentation is available via anonymous FTP it is indicated by a World Wide Web URL like:
1899 <ftp://athena-dist.mit.edu/pub/kerberos/doc/usenix.PS>
1901 where: athena-dist.mit.edu is the anonymous FTP site and pub/kerberos/doc/usenix.PS is the filename
1903 Similarly, for those who have appropriate access, documents available via AFS are shown with the format:
1907 [1] John H Howard, Michael L Kazar, Sherri G Menees, David A Nichols, M Satyanarayanan, Robert N Sidebotham, Michael J West "Scale and Performance in a Distributed File System", ACM Transactions on Computer Systems, Vol. 6, No. 1, Feb 1988 pp 51-81.
1909 [2] Michael L Kazar, "Synchronisation and Caching Issues in the Andrew File System", USENIX Proceedings, Dallas, TX, Winter 1988
1911 [3] Alfred Z Spector, Michael L Kazar, "Uniting File Systems", UNIX Review, March 1989
1913 [4] Johna Till Johnson, "Distributed File System brings LAN Technology to WANs", Data Communications, November 1990, pp 66-67.
1915 [5] Michael Padovano, PADCOM Associates, "AFS widens your horizons in distributed computing", Systems Integration, March 1991
1917 [6] Steve Lammert, "The AFS 3.0 Backup System", LISA IV Conference Proceedings, Colorado Springs, Colorado, October 1990.
1919 [7] Michael L Kazar, Bruce W Leverett, Owen T Anderson, Vasilis Apostolides, Beth A Bottos, Sailesh Chutani, Craig F Everhart, W Anthony Mason, Shu-Tsui Tu, Edward R Zayas, "DEcorum File System Architectural Overview", USENIX Conference Proceedings, Anaheim, Texas, Summer 1990.
1921 [8] "AFS Drives DCE Selection", Digital Desktop, Vol 1 No 6 Sept 1990.
1923 [9] James J Kistler, M Satyanarayanan, "Disconnected Operation in the Coda Filesystem", CMU School of Computer Science technical report, CMU-CS-91-166 26th July 1991.
1925 [10] Puneet Kumar. M Satyanarayanan, "Log-based Directory Resolution in the Coda File System", CMU School of Computer Science internal document, 2 July 1991.
1927 [11] Edward R Zayas, "Administrative Cells: Proposal for Cooperative Andrew File Systems", Information Technology Center internal document, Carnegie-Mellon University, 25th June 1987
1929 [12] Ed Zayas, Craig Everhart, "Design and Specification of the Cellular Andrew Environment", Information Technology Center, Carnegie-Mellon University, CMU-ITC-070, 2 August 1988
1931 [13] Kazar, Michael L, Information Technology Center, Carnegie-Mellon University, "Ubik - A library for Managing Ubiquitous Data", ITCID, Pittsburgh, PA, 1988
1933 [14] Kazar, Michael L, Information Technology Center, Carnegie-Mellon University, "Quorum Completion", ITCID, Pittsburgh, PA, 1988
1935 [15] SP Miller, BC Neuman, JI Schiller, JH Saltzer, "Kerberos Authentication and Authorization System", Project Athena technical Plan, Section E.2.1, MIT, December 1987 <ftp://athena-dist.mit.edu/pub/kerberos/doc/techplan.PS> <ftp://athena-dist.mit.edu/pub/kerberos/doc/techplan.txt> <file:///afs/watson.ibm.com/projects/agora/papers/kerberos/techplan.PS>
1937 [16] Bill Bryant, "Designing an Authentication System: a Dialogue in Four Scenes", Project Athena internal document, MIT, draft of 8th February 1988 <ftp://athena-dist.mit.edu/pub/kerberos/doc/dialogue.PS> <ftp://athena-dist.mit.edu/pub/kerberos/doc/dialogue.mss> <file:///afs/watson.ibm.com/projects/agora/papers/kerberos/dialogue.PS>
1939 [17] Edward R Zayas, "AFS-3 Programmer's Reference: Architectural Overview", Transarc Corporation, FS-00-D160, September 1991 <ftp://ftp.transarc.com/pub/afsps/doc/progint/archov-doc.ps> <ftp://ftp.transarc.com/pub/afsps/doc/progint/archov-doc.dvi> <file:///afs/transarc.com/public/afsps/doc/progint/archov-doc.ps> <file:///afs/transarc.com/public/afsps/doc/progint/archov-doc.dvi> <file:///afs/watson.ibm.com/projects/agora/papers/afs/archov-doc.ps>
1941 [18] "AFS Programmer's Reference: Authentication Server Interface", Transarc Corporation, 12th April 1993 <ftp://ftp.transarc.com/pub/afsps/doc/progint/asrv-ispec.ps> <ftp://ftp.transarc.com/pub/afsps/doc/progint/asrv-ispec.dvi> <file:///afs/transarc.com/public/afsps/doc/progint/asrv-ispec.ps> <file:///afs/transarc.com/public/afsps/doc/progint/asrv-ispec.dvi> <file:///afs/watson.ibm.com/projects/agora/papers/afs/asrv-ispec.ps>
1943 [19] Edward R Zayas, "AFS-3 Programmer's Reference: BOS Server Interface", Transarc Corporation, FS-00-D161, 28th August 1991 <ftp://ftp.transarc.com/pub/afsps/doc/progint/bsrv-spec.ps> <ftp://ftp.transarc.com/pub/afsps/doc/progint/bsrv-spec.dvi> <file:///afs/transarc.com/public/afsps/doc/progint/bsrv-spec.ps> <file:///afs/transarc.com/public/afsps/doc/progint/bsrv-spec.dvi> <file:///afs/watson.ibm.com/projects/agora/papers/afs/bsrv-spec.ps>
1945 [20] Edward R Zayas, "AFS-3 Programmer's Reference: File Server/Cache Manager Interface", Transarc Corporation, FS-00-D162, 20th August 1991 <ftp://ftp.transarc.com/pub/afsps/doc/progint/fscm-ispec.ps> <ftp://ftp.transarc.com/pub/afsps/doc/progint/fscm-ispec.dvi> <file:///afs/transarc.com/public/afsps/doc/progint/fscm-ispec.ps> <file:///afs/transarc.com/public/afsps/doc/progint/fscm-ispec.dvi> <file:///afs/watson.ibm.com/projects/agora/papers/afs/fscm-ispec.ps>
1947 [21] Edward R Zayas, "AFS-3 Programmer's Reference: Specification for the Rx Remote Procedure Call Facility", Transarc Corporation, FS-00-D164, 28th August 1991 <ftp://ftp.transarc.com/pub/afsps/doc/progint/rx-spec.ps> <ftp://ftp.transarc.com/pub/afsps/doc/progint/rx-spec.dvi> <file:///afs/transarc.com/public/afsps/doc/progint/rx-spec.ps> <file:///afs/transarc.com/public/afsps/doc/progint/rx-spec.dvi> <file:///afs/watson.ibm.com/projects/agora/papers/afs/rx-spec.ps>
1949 [22] Edward R Zayas, "AFS-3 Programmer's Reference: Volume Server/Volume Location Server Interface", Transarc Corporation, FS-00-D165, 29th August 1991 <ftp://ftp.transarc.com/pub/afsps/doc/progint/vvl-spec.ps> <ftp://ftp.transarc.com/pub/afsps/doc/progint/vvl-spec.dvi> <file:///afs/transarc.com/public/afsps/doc/progint/vvl-spec.ps> <file:///afs/transarc.com/public/afsps/doc/progint/vvl-spec.dvi> <file:///afs/watson.ibm.com/projects/agora/papers/afs/vvl-spec.ps>
1951 [23] "AFS User Guide", Transarc Corporation, FS-D200-00.08.3
1953 [24] "AFS Commands Reference Manual", Transarc Corporation, FS-D200-00.11.3
1955 [25] "AFS Systems Administrators Guide", Transarc Corporation, FS-D200-00.10.3
1957 [26] Steven M. Bellovin, Michael Merritt "Limitations of the Kerberos Authentication System", Computer Communications Review, October 1990, Vol 20 #5, pp. 119-132 [ftp://research.att.com/dist/internet\_security/kerblimit.usenix.ps](ftp://research.att.com/dist/internet_security/kerblimit.usenix.ps) <file:///afs/watson.ibm.com/projects/agora/papers/kerberos/limitations.PS>
1959 [27] Jennifer G. Steiner, Clifford Neuman, Jeffrey I. Schiller "Kerberos: An Authentication Service for Open Network Systems" <ftp://athena-dist.mit.edu/pub/kerberos/doc/usenix.PS> <ftp://athena-dist.mit.edu/pub/kerberos/doc/usenix.txt>
1961 [28] Barry Jaspan "Kerberos Users' Frequently Asked Questions" <ftp://rtfm.mit.edu/pub/usenet/news.answers/kerberos-faq/user> <http://www.ov.com/misc/krb-faq.html>
1963 [29] P. Honeyman, L.B. Huston, M.T. Stolarchuk "Hijacking AFS" <ftp://ftp.sage.usenix.org/pub/usenix/winter92/hijacking-afs.ps.Z> [file:///afs/watson.ibm.com/projects/agora/papers/afs/afs\_hijacking.ps](file:///afs/watson.ibm.com/projects/agora/papers/afs/afs_hijacking.ps)
1965 [30] R.N. Sidebotham "Rx: Extended Remote Procedure Call" Proceedings of the Nationwide File System Workshop Information Technology Center, Carnegie Mellon University, (August 1988)
1967 [31] R.N. Sidebotham "Volumes: The Andrew File System Data Structuring Primitive" Technical Report CMU-ITC-053, Information Technology Center, Carnegie Mellon University, (August 1986)
1969 [32] Cohen, David L. "AFS: NFS on steroids", LAN Technology March 1993 v9 n3 p51(9) [ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/NFS\_on\_steroids](ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/NFS_on_steroids)
1971 [33] Marybeth Schultz "AFS Troubleshooting Tools" Transarc Corporation, January 11 1993, draft document <ftp://ftp.transarc.com/pub/afsps/doc/trguide/external.afsug.ps>
1973 [34] William Stallings "Kerberos Keeps the Enterprise Secure" Data Communications, October 1994, Vol 23 No 14 Page 103
1975 [35] DL Mills "Internet Time Synchronization: the Network Time Protocol" RFC 1129, October 1989 <ftp://nic.ddn.mil/rfc/rfc1129.ps>
1977 [36] DL Mills "Network Time Protocol (Version 3) Specification, Implementation and Analysis" RFC 1305, March 1992 <ftp://nic.ddn.mil/rfc/rfc1305.tar.Z> <ftp://nic.ddn.mil/rfc/rfc1305.txt>
1979 [37] Craig Everhart "Conventions for Names in the Service Directory in the AFS Distributed File System" March 1990 <ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/service-spec.ez.ps> <ftp://ftp.transarc.com/pub/afs-contrib/doc/faq/service-spec.ez> <file:///afs/transarc.com/public/afs-contrib/doc/faq/service-spec.ez> <file:///afs/transarc.com/public/afs-contrib/doc/faq/service-spec.ez.ps>
1981 [38] AFS Programmer's Reference Manual <ftp://ftp.transarc.com/pub/afsps/doc/progref/3.0/> <file:///afs/transarc.com/public/afsps/doc/progref/3.0/>
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