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IC97618: BACKGROUND PROCESS OF DELETING DEREFERENCED DEDUPLICATED CHUNKS MAY APPEAR STUCK AFTER DELETING LARGE AMOUNT OF FILESPACE DATA

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APAR status

  • Closed as program error.

Error description

  • It is possible that a backlog of dereferenced deduplicated
    chunks might occur after a large amount of data is deleted. The
    deletion might occur as a result of expiration or by an explicit
    deletion request such as DELETE VOLUME or DELETE FILESPACE. The
    result will be that there are hundreds of millions of chunks to
    be processed by the background deletion engine.
    The backlog and lack of progress can be confirmed with the
    output from the SHOW DEDUPDELETEINFO command. The key column to
    look at is the "Number of chunks waiting in queue" as that will
    show hundreds of millions of chunks and will continue to
    increase over time.
    Example:
    tsm: SERVER>show dedupdelete
    ****Dedup Deletion General Status****
    Number of worker threads          : 16
    Number of active worker threads   : 2
    Number of chunks waiting in queue : 583397475
    NOTE: The abnormally large backlog does not usually occur
    from a standard expiration of deduplicated objects. In order
    to be affected by this APAR an abnormal amount of objects
    would have to be deleted from the server system. In some
    cases, this has come from the movement of deduplicated
    data OUT of a storage pool which leads to the same
    dereferencing action as an explicit deletion request such
    as expire, delete volume, delete filespace, etc..
    Tivoli Storage Manager Versions Affected: 6.1, 6.2 and 6.3
    Initial Impact: Medium
    Additional Keywords: performance, dedup, cleanup, chunks,
    dedupe, degrade, degradation, slow, hung, hang, perf
    

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 levels 6.3.4.300, 6.3.5, and 7.1.1.       *
    *                 Note that this is subject to change at the   *
    *                 discretion of IBM.                           *
    ****************************************************************
    *
    

Problem conclusion

  • This problem was fixed.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC97618

  • Reported component name

    TSM SERVER

  • Reported component ID

    5698ISMSV

  • Reported release

    63W

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-11-12

  • Closed date

    2013-11-14

  • Last modified date

    2013-12-06

  • 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: 63W

Reference #: IC97618

Modified date: 06 December 2013