dafs-kill-xcpu-dump-vlru-stats-20080318

dafs-kill-xcpu-dump-vlru-stats-20080318

LICENSE BSD

this will dump the current dafs vlru state on kill -XCPU (just as we dump other fileserver state)

that state is
VLRU is a garbage collection facility which automatically offlines
volumes in the background. The purpose of this facility is to
proactively offline infrequently used volumes to improve shutdown and
salvage times. The process of offlining a volume from the "attached"
state to the "pre-attached" state is called soft detachment.

VLRU works in a manner similar to a generational garbage collector.
There are five queues on which volumes can reside: new, intermediate,
old, held, and candidate:

held:

queue for volumes which are administratively barred from VLRU activity

candidate:

queue for volumes which have not been accessed recently, and are thus
candidates for soft detachment

new, intermediate, old:

generational queues for active volumes; state transitions controlled by
inactivity timers.

State transition timeouts are as follows:

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 (2*vlruthresh) minutes since last transition; no activity
mid->new (1*vlruthresh) minutes since last transition; no activity