PM80804: USER LOB TABLE SPACE GROWTH WHEN SHARED BUFFER POOL WITH DSNDB01 SPT01

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A user LOB table space was growing.
    This was due to a seemingly old value for read claim lrsn for
    the buffer pool. LOB space reuse is tracked at buffer pool level
    using oldest read claim LRSN. Any objects using a 32k buffer
    pool are considered when calculating the oldest reader Lrsn. The
    buffer pool was also shared by directory LOB table space
    dsndb01.spt01 and there was an old commit-LRSN for DSNDB01.SPT01
    which caused the problem.
    Additional keywords: commit lsn , read lsn , read only .
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: DB2 data sharing users.                      *
    ****************************************************************
    * PROBLEM DESCRIPTION: Table space growth due to old read-lsn  *
    *                      value.                                  *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Any table space with a LOB column will register its commit-lsn
    as a read-lsn.  However, the commit-lsn value can be very old
    if the object has been read-only for a long time.  This old
    read-lsn gets propagated to the buffer pool level in data
    sharing, and can prevent space reuse for other objects sharing
    the same buffer pool.
    

Problem conclusion

  • The code which registers a commit-lsn as a read-lsn has been
    modified to use the current end-of-log lrsn if the object is
    currently read-only, rather than its local commit-lsn value.
    Additionally, the local commit-lsn tracking will be improved
    to allow for advancement when another member gives up its
    update interest.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM80804

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-01-17

  • Closed date

    2013-02-28

  • Last modified date

    2013-04-02

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

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

    UK92094

Modules/Macros

  •    DSNB1CLM DSNB1PPP
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UK92094

       UP13/03/16 P F303

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



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Document information


More support for:

DB2 for z/OS

Software version:

A10

Reference #:

PM80804

Modified date:

2013-04-02

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