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IT14336: SERVER DATABASE BACKUP PERFORMANCE AFFECTED BY DB2 FLUSH ACTIVITY AS MANAGED WITH OPTIONS SOFTMAX AND PAGE_AGE_TRGT_MCR

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APAR status

  • Closed as program error.

Error description

  • Database backup can encounter performance issues when DB2 is
    waiting to flush the dirty pages from the DB2 buffer pool. When
    this issue occurs, the database backup will be slow in starting
    the $$_TSMDBMGR_$$ sessions or a QUERY PROCESS after the
    sessions have started will not show any progress.. For example,
    QUERY PROCESS output:
    
    Process  Process Description  Process Status
    Number
    -------- -------------------- -----------------------------
    
    2,087    Database Backup      TYPE=FULL in progress. Bytes
                                  backed up:
                                  768 GB. Current output
                                  volume(s):500193L4.
    
    The Bytes backed up will not change for a long time, could be
    hours. The process look hung. The hang can occur anytime during
    the operation, but it will eventually continue after some amount
    of time.
    
    In depth db2 analysis has revealed that the database backup
    processing is waiting for DB2 buffer pool flushes to complete
    before it can proceed. To expedite the flush activity the DB2
    option page_age_trgt_mcr can be used to specify how long the
    changed pages remain in the DB2 buffer pool. This option can
    only be used if the DB2 SOFTMAX value is set to zero. Because
    the server code currently does not allow for the SOFTMAX value
    to be set to zero this APAR is being taken to change to server
    to allow the zero setting. Once this is the case the default
    page_age_trgt_mcr value of 240 be used and the need the database
    backup to wait for buffer pool flushes should be reduced.
    
    Tivoli Storage Manager Versions Affected:
    All supported IBM Spectrum Protect server
    Tivoli Storage Manager server 7.1
    
    Customer/L2 Diagnostics (If Applicable)
    To determine if the customer is affected by this APAR, the
    servermon script should be run for the entire duration of the DB
    backup. The files created by servermon ending in "db2pd.txt"
    need to be examined, looking for the section titled
    "Bufferpool: 2 ".  This section shows the count of the number of
    "dirty pages" needing to be flushed to disk before the backup
    can begin or proceed. If the customer is affected by this APAR,
    then Bufferpool 2 will show thousands of pages needing to be
    flushed before the $$_TSMDBMGR_$$ sessions can begin. Also, If
    the DB backup appears to stall or hang in the middle of the
    backup, then this section will show thousands of pages needing
    to be flushed before the backup can proceed again. The output
    will look like:
    Bufferpool: 2
        Dirty pages %       : 726383 / 8406224 (8.64% dirty)np
    
    Initial Impact:
    Low
    
    Additional Keywords:
    TSM backup db slow
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All Tivoli Storage Manager server users.                     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See error description.                                       *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply fixing level when available. This problem is currently *
    * projected to be fixed in level 7.1.6. Note that this is      *
    * subject to change at the discretion of IBM.                  *
    ****************************************************************
    

Problem conclusion

  • This problem was fixed.
    Affected platforms:  AIX, HP-UX, Solaris, Linux, and Windows.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT14336

  • Reported component name

    TSM SERVER

  • Reported component ID

    5698ISMSV

  • Reported release

    71W

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-03-24

  • Closed date

    2016-03-30

  • Last modified date

    2016-03-30

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    TSM SERVER

  • Fixed component ID

    5698ISMSV

Applicable component levels

  • R71A PSY

       UP

  • R71H PSY

       UP

  • R71L PSY

       UP

  • R71S PSY

       UP

  • R71W PSY

       UP



Document information

More support for: Tivoli Storage Manager

Software version: 7.1.3

Reference #: IT14336

Modified date: 30 March 2016