<li><a href="#3.44 I get error message trhough"> 3.44 I get error message trhough syslogd: "afs: Tokens for user of AFS id 0 for cell foo.bar.baz are discarded (rxkad error=19270407)"</a></li>
<li><a href="#3.45 I get tickets and tokens, b"> 3.45 I get tickets and tokens, but still get Permission denied.</a></li>
<li><a href="#3.46 Recovering broken afs cache"> 3.46 Recovering broken afs cache on clients</a></li>
+ <li><a href="#3.47 What does it mean for a vol"> 3.47 What does it mean for a volume to not be in the VLDB?</a></li>
+ <li><a href="#3.48 What is a Volume Group?"> 3.48 What is a Volume Group?</a></li>
+ <li><a href="#3.49 What is a Clone?"> 3.49 What is a Clone?</a></li>
+ <li><a href="#3.50 What is a Shadow?"> 3.50 What is a Shadow?</a></li>
</ul>
</li>
</ul>
[ other ls results as usual ]
Flushing a particular file had no effect (the same error as shown above appears). Flushvolume took a long time, but when it eventually completed, the ls -la behaved exactly as one would expect.
+
+### <a name="3.47 What does it mean for a vol"></a> 3.47 What does it mean for a volume to not be in the VLDB?
+
+If a volume is not in the VLDB, you will be unable to perform operations on it using its name; all "vos" operations will need to be done using its numerical id, server, and partition. Furthermore, if a volume is not in the VLDB, it cannot be reached via mountpoints.
+
+### <a name="3.48 What is a Volume Group?"></a> 3.48 What is a Volume Group?
+
+A volume group is a set of volumes whose volume id numbers differ only in the last three bits. This means that up to eight volumes may belong to a single volume group.
+
+Volumes which share storage on a partition (for example, a volume and its backup, or the r/w and r/o copy of a volume on the same partition) must be part of the same volume group.
+
+### <a name="3.49 What is a Clone?"></a> 3.49 What is a Clone?
+
+A clone of a volume is a read-only copy of that volume which shares on-disk storage with the original volume. Backup volumes are a particular kind of clone volume. Read-only replicas which reside on the same partition as their read-write volume are another particular kind of clone volume. In some other storage systems this kind of volume is called a "snapshot".
+
+Clone volumes must belong to the same volume group (see previous question) as the volume which they are a clone of.
+
+In addition to backup and readonly clones, you may create up to three additional clones of a volume. To do this, use "vos clone".
+
+When you "vos remove" a volume, its "backup" clone will also be removed automatically. However, clones created with "vos clone" are **not** removed automatically. Unfortunately, these "dangling clones" will no longer be in the VLDB (see question 3.47). They belong to a volume group whose leader (rw volume) no longer exists, which is a somewhat undefined state for AFS. Such volumes should be manually deleted as soon as possible.
+
+### <a name="3.50 What is a Shadow?"></a> 3.50 What is a Shadow?
+
+A shadow of a volume is a duplicate of that volume which resides on a different partition. Shadow volumes do not share storage with their original volumes (unlike clones). A readonly volume on a **different** partition than its readwrite volume could be considered one particular example of a shadow volume; however, in practice the term "shadow volume" is used to refer to volumes created with "vos shadow" and not to refer to readonly volumes.
+
+A shadow of any readwrite volume may be created using the "vos shadow" command. This will create a new volume which is a shadow of the original volume, and will copy the contents of the old volume to the new volume. This will also set a bit in the header of the new shadow volume that identifies it as a shadow volume. Shadow volumes do not appear in the VLDB (see question 3.47) -- "vos shadow" does not create a VLDB entry and "vos syncvldb" ignores shadow volumes.
+
+You can "refresh" a shadow volume from its original with "vos shadow -incremental". This operation will first check to make sure that the target of the operation is a shadow volume, to prevent the administrator from accidentally corrupting a non-shadow volume. However, if you shadow from a readwrite volume to some shadow of **another** volume, the shadow will be corrupted and will have to be deleted. Vos shadow will only copy data which has changed, so it is very efficient.
+
+You can remove the shadow bit from a volume's header with "vos shadow -force". This will remove the shadow bit and create a VLDB entry for the volume, deleting any previous entry for the rw volume. However, the rw volume itself will not be deleted; it will simply exist without a VLDB entry.
+
+Attempting to create shadows of two different rw volumes on the same partition with the same name is prohibited by the volserver. Technically it is possible to create two shadow volumes with the same name on different partitions; however, this is not advisable.
git://git.openafs.org / openafs-wiki.git / blobdiff