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IT20212: VERY SLOW CRASH RECOVERY CAUSED BY DB2 APAR IT18691

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • DB2 APAR IT18691 can cause very slow rollback.  This issue can
    happen When a log record needed for rollback is not available in
     a memory buffer, the agent performing the rollback needs to
    retrieve this from disk. Due to poor caching, this can lead to a
     bottleneck with many reads having to be performed by the
    db2loggr.
    
     .
    
    L2/customer diagnostics:
    
     Spectrum Protect users can see this happen  when some very
    large transactions got cut because of num_log_span, or cancel
    process/session.  the  rollback of such transaction can be very
    slow.  The same slowness can also be observed during  crash
    recovery
    
    When the slow rollback is observed,  execute the following
    command as instance owner:
    
    db2pd -latches | grep SQLO_LT_SQLP_DBCB__ReadBufSem
    0x0A00020000061940 793497     273710     sqlpgrlg.C 1553
    SQLO_LT_SQLP_DBCB__ReadBufSem 1
    0x0A00020000061940 793497     110666     sqlpgrlg.C 1553
    SQLO_LT_SQLP_DBCB__ReadBufSem 1
    0x0A00020000061940 793497     471206     sqlpgrlg.C 1553
    SQLO_LT_SQLP_DBCB__ReadBufSem 1
    0x0A00020000061940 793497     641753     sqlpgrlg.C 1553
    SQLO_LT_SQLP_DBCB__ReadBufSem 1
    
    
    3rd column of above output present the number of waiters , a
    high value of waiter hint the  latch contention
    .
    Platform /Version affected:
    IBM Spectrum protect users on all supported platform and
    versions
    .
    Additional keywords
    rollback slow  IT18691
    

Local fix

  • preventing very slow long running transaction can help to reduce
     the in-flight transaction size and preventing the situation
    from happening.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All Tivoli Storage Manager and IBM Spectrum Protect server   *
    * users.                                                       *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See error description.                                       *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply fixing level when available. This problem is currently *
    * projected to be fixed in levels 7.1.8 and 8.1.2. Note that   *
    * this is subject to change at the discretion of IBM.          *
    ****************************************************************
    

Problem conclusion

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

Temporary fix

Comments

APAR Information

  • APAR number

    IT20212

  • Reported component name

    TSM SERVER

  • Reported component ID

    5698ISMSV

  • Reported release

    71A

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-04-19

  • Closed date

    2017-05-30

  • Last modified date

    2017-05-30

  • 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

  • R81A PSY

       UP

  • R81L PSY

       UP

  • R81W PSY

       UP

  • 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 #: IT20212

Modified date: 30 May 2017