I'm running GPFS 3.5.0.9 under Linux, and I'm seeing what seem to be an
excessive number of lowDiskSpace events on the "system" pool.
I've got an mmcallback set up, including a log report of which pool is
triggering the lowDiskSpace callback.
The part that is confusing me is that the "system" pool doesn't seem to be
above the policy thresholds.
For example, 'mmdf' shows that there is about 26% free in the 'system' pool:
-------------------------
disk disk size failure holds holds free free
name group metadata data in full blocks in
fragments
--------------- ------------- -------- -------- ----- --------------------
-------------------
Disks in storage pool: system (Maximum disk size allowed is 33 TB)
dx80_rg16_vol1 546G -1 yes yes 125.1G ( 23%)
23.96G ( 4%)
dx80_rg4_vol1 546G 1 yes yes 108.1G ( 20%)
33.84G ( 6%)
dx80_rg13_vol1 546G 1 yes yes 109G ( 20%)
32.78G ( 6%)
dx80_rg6_vol1 546G 1 yes yes 104.4G ( 19%)
35.61G ( 7%)
dx80_rg3_vol1 546G 1 yes yes 105.6G ( 19%)
35.29G ( 6%)
------------- --------------------
-------------------
(pool total) 2.666T 552.1G ( 20%)
161.5G ( 6%)
-------------------------
The current policy has several rules related to the "system" pool:
-------------------------
RULE 'move large files (50MB+) in the system pool to dx80_medium' MIGRATE FROM
POOL 'system'
TO POOL 'dx80_medium'
THRESHOLD(77,70)
LIMIT(95)
WEIGHT(KB_ALLOCATED)
WHERE FILE_SIZE >= 52428800
/* highest threshold = least free space, move newest files greater than 1MB */
RULE 'move files that have not been changed in 3 days from the system pool to
dx80_medium' MIGRATE FROM POOL 'system'
TO POOL 'dx80_medium'
THRESHOLD(76,70)
LIMIT(95)
WEIGHT(KB_ALLOCATED)
WHERE (DAYS(CURRENT_TIMESTAMP) - DAYS(CHANGE_TIME) > 3 )
AND KB_ALLOCATED >= 1024
/* next threshold: some free space, move middle-aged files */
RULE 'move files that have not been changed in 7 days from the system pool to
dx80_medium' MIGRATE FROM POOL 'system'
TO POOL 'dx80_medium'
THRESHOLD(75,65)
LIMIT(95)
WEIGHT(KB_ALLOCATED)
WHERE (DAYS(CURRENT_TIMESTAMP) - DAYS(CHANGE_TIME) > 7 )
AND KB_ALLOCATED >= 1024
-------------------------
As I understand it, none of those rules should trigger a lowDiskSpace event
when the pool is 74% full, as it is now.
Is the threshold in a file migration policy based on the %free (or used) in
full blocks only, or in the sum of full blocks plus fragments?
Thanks,
Mark
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