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IT10704: RESTORE STGPOOL FOR DATA DEDUPLICATION STGPOOL MAY CAUSE PERFORMANCE DEGRADATION OF IDENTIFY DUPLICATE OR BACKUP STGPOOL

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • After RESTORE STGPOOL to the data deduplication storage pool
    from the copy storage pool completed, IDENTIFY DUPLICATE or
    BACKUP STGPOOL on the restored storage pool may take long time
    to complete.
    
    To determine if the issue can be caused by this APAR, do the
    following steps:
    
    1. By executing the following SQL, check if a large number of
    duplicate copies of the base chunk exist.
    
    db2 "select digest_value, linkbfid, count(*) as count from
    tsmdb1.bf_bitfile_extents where linkbfid is null group by
    digest_value,linkbfid  having count(*) > 100 with ur"
    
    Example:
    
    DIGEST_VALUE                                LINKBFID
    COUNT
    ------------------------------------------- --------------------
    -----------
    x'16E1F2786521AFCFF8A7FF1278224D29C457CAC9'                    -
    55470
    x'94A8FEC48CCD80E8D48773193E876E3D814443F4'                    -
    116590
    ...
    
    2. In the server instrumentation trace by servermonV6.pl with
    enabling $sqlstats="Y" being gathered during IDENTIFY DUPLICATE
    or BACKUP STGPOOL, check if the following SQL statement
    noticeably takes a long time to run.
    
    SELECT be.bfid, bf.length, bf.flags, be.pending_id,
    bf.uncomp_length FROM TSMDB1.bf_bitfile_extents AS be LEFT JOIN
    TSMDB1.bf_aggregated_bitfiles AS bf ON ( bf.srvid=be.srvid AND
    bf.bfid=be.bfid AND  bf.superbfid=be.superbfid AND bf.length>0)
    LEFT JOIN TSMDB1.af_damaged AS da ON ( be.srvid=da.srvid AND
    be.poolid=da.poolid AND be.superbfid=da.bfid ) WHERE be.srvid=0
    AND be.poolid=? AND be.digest_type=? AND  be.digest_value=? AND
    be.size=? AND be.linkbfid IS NULL AND  be.bfid !=? AND da.srvid
    IS NULL AND   ( be.pending_id IS NULL OR be.pending_id=? ) FETCH
    FIRST 10 ROWS ONLY FOR READ ONLY WITH CS;
    
    For the problem to occur during RESTORE STGPOOL:
    - The primary pool must have dedup enabled.
    - The copy pool can be any pool.  dedup, not dedup, tape, ...
    - Must be restoring large objects containing many copies of the
    same duplicate chunk that does not already exist in the primary
    pool.  Sparse or pre-allocated files in particular have zeros
    repeated throughout the file.
    
    Tivoli Storage Manager Versions Affected:
    Tivoli Storage Manager Server 6.3 and 7.1 on all supported
    platform
    
    Initial Impact:
    Middle
    

Local fix

  • Turn off dedup on the primary storage pool before doing restore.
    It will need to restore all the data intact.  Identify can later
    be run in order to deduplicate the data by linking the restored
    chunks that already have a digest value which will save time.
    

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 levels 6.3.6, 7.1.3.100, and 7.1.4. *
    * 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

    IT10704

  • Reported component name

    TSM SERVER

  • Reported component ID

    5698ISMSV

  • Reported release

    63A

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2015-08-17

  • Closed date

    2015-09-28

  • Last modified date

    2015-09-28

  • 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

  • R63A PSY

       UP

  • R63H PSY

       UP

  • R63L PSY

       UP

  • R63S PSY

       UP

  • R63W 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: 63A

Reference #: IT10704

Modified date: 28 September 2015