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[openafs-wiki.git] / AFSLore / DemandAttach.mdwn

diff --git a/AFSLore/DemandAttach.mdwn b/AFSLore/DemandAttach.mdwn
index 157c031..b66aa3d 100644 (file)
--- a/AFSLore/DemandAttach.mdwn
+++ b/AFSLore/DemandAttach.mdwn
@@ -13,18 +13,20 @@ The key engine for offlining volumes is the VLRU (Volume Least Recently Used) qu
 VLRU works in a manner similar to a generational garbage collector. There are five queues on which volumes can reside:
 
 1. new
-2. intermediate
+2. mid
 3. old
 4. held: queue for volumes which are administratively barred from VLRU activity
 5. candidate: queue for volumes which have not been accessed recently, and thus are canddidates for soft detachment
 
-The new, intermediate, and old queues are generational queues for active volumes, with the state transitions among them controlled by the following inactivity rules:
+The new, mid, and old queues are generational queues for active volumes, with the state transitions among them controlled by the following inactivity rules:
 
 - candidate->new activity present
 - new->candidate (1\*vlruthresh) minutes since last transition; no activity
 - new->mid (2\*vlruthresh) minutes since last transition; activity present
 - mid->old (4\*vlruthresh) minutes since last transition; activity present
-- old->mid 92\*vlruthresh) minutes since last transition; no activity
+- old->mid (2\*vlruthresh) minutes since last transition; no activity
 - mid->new (1\*vlruthresh) minutes since last transition; no activity
 
+The idea is that as a volume is used, it gets pushed into a 'more used' generation (i.e., 'old' is 'more used' than 'mid', which is 'more used' than 'new'). this provides a weighting so that volumes which are used more will tend to be in the mid and old queues, not in the new or candidate queues, thus staying in online.
+
 Note that the VLRU engine can be controlled and tuned by the vlrudisable, vlruthresh, vlruinterval, and vlrumax parameters to the fileserver.