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  1. #1
    Join Date
    Mar 2006
    Tuticorin, India

    Unanswered: DB2 Backup with TSM Optimization

    Env: DB2 9.1/AIX 5.3
    Database size: 750 GB
    No of tablespaces : 40

    Complete offline backup runs for 3 hours with the following options
    UTIL_HEAP_SZ = 5000
    backup db xxx use tsm open 2 sessions.

    Which is a best option to improve the performance
    [1] Increase UTIL_HEAP_SZ to 10,000 ?
    [2] Use more sessions with TSM (4) ?
    [3] WITH num_buffers BUFFERS parameter ?

    Any thoughts ?

  2. #2
    Join Date
    Aug 2008
    Toronto, Canada
    You can find some general performance guidelines here:
    DB2 Database for Linux, UNIX, and Windows

    Limited by maxnummp TSM parameter so # of sessions should not be greater than maxnummp

    WITH num-buff BUFFERS
    The following calculation must fit: (num-buffers * buffer-size) < util_heap_sz

    Or you can let DB2 choose the value, if it's not specified. You can see what db2 used with diaglevel 4.

    You can also consider using incremental/delta backups. A tablespace will be skipped if there are no changed pages.

  3. #3
    Join Date
    Feb 2009
    The problem is usually in the network between db and TSM plus the inherent inefficiencies of the TSM API. Backup to disk (small fraction of API time) and have TSM pick it up from there. Of course, with this scenario, you have to be prepared to put files back on disk from TSM manually before doing RESTORE.

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