GENERATE BACKUPSET performance suddenly drops

Technote (troubleshooting)


Problem(Abstract)

Collocation and Active Data pool are used to speed up generate backupset operations, like recommended but suddenly the backupset operations become very long.
The activity log show a lot of mount and dismount for the same volumes during the process.

Symptom

Same input volume mounted many time :

ANR8340I FILE volume X:\tsmstg\vol111.bfs mounted. (SESSION: 8360, PROCESS: 628)
ANR0512I Process 628 opened input volume X:\tsmstg\vol111.bfs. (SESSION: 8360,
PROCESS: 628)
ANR0515I Process 628 closed volume X:\tsmstg\vol111.bfs. (SESSION: 8360,
PROCESS: 628)
....

ANR8340I FILE volume X:\tsmstg\vol111.bfs mounted. (SESSION: 8360, PROCESS: 628)
ANR0512I Process 628 opened input volume X:\tsmstg\vol111.bfs. (SESSION: 8360,
PROCESS: 628)
ANR0515I Process 628 closed volume
X:\tsmstg\vol111.bfs. (SESSION: 8360,
PROCESS: 628)


Cause

Active Data pool was changed from deduplicated to non-deduplicated storage pool.
There is a server option named NUMOPENVOLSALLOWED , that allow multiple FILE volumes to be opened at one time, but only for dedup pool volume . The option default to 10.
When disabling deduplication, this option has no more effect and file reconstruction bring this mount/dismount issue.


Environment

All platform, version 6 releases.

Diagnosing the problem

Look if you see the same input volume mounted many times. If this is the case run the following DB2 select command. That will show if one stgpool was changed from dedup to non dedup :

db2 connect to tsmdb1
db2 "select poolname, deduplicate from tsmdb1.ss_pools"

The stgpool which has field DEDUPLICATE equal to 2 was a dedup pool but was disabled.

For example:
$ db2 "select poolname, deduplicate from ss_pools"

POOLNAME DEDUPLICATE
------------------------------- -----------
BACKUPPOOL 0
ARCHIVEPOOL 0
SPACEMGPOOL 0
FILEPOOL 2
FILEPOOL2 1
ADPOOL 1
COPYDEDUP 1
COPYNODEDUP 0

Storage pool FILEPOOL was dedup but was disabled.


Resolving the problem

Change the non dedup storage pool back to dedup, or wait that all files in the affected storage pool are stored in non deduplicated format.

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Document information


More support for:

Tivoli Storage Manager
Server

Software version:

6.1, 6.2, 6.3, 6.4, 7.1

Operating system(s):

All Platforms

Reference #:

1617847

Modified date:

2014-01-27

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