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PI12512: BPOOL STORAGE CALCULATION CHANGE IF PGFIX=Y WITH 1MB FRAMES & VPSIZE IS SMALL (LESS THAN 6656), ALLOW 1MB FIXED STG ALLOCATION

A fix is available

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APAR status

  • Closed as program error.

Error description

  • When 1MB is allocated for the control blocks, these control
    blocks can cover 6656 buffers in the buffer pool.  For a small
    buffer pool (VPSIZE is less than 6656), DB2 allocates buffers
    using 4K frames to avoid wasting 1MB fixed storage.  Storage
    calculation will be adjusted to allow  1MB fixed storage
    allocation for  VPSIZE  that is less than  6656.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All DB2 users.                               *
    ****************************************************************
    * PROBLEM DESCRIPTION: For a small PGFIX=YES buffer pool with  *
    *                      VPSIZE less than 6656, DB2 allocates    *
    *                      page buffers using 4K frames.           *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    DB2 uses control blocks to track page buffers in a buffer pool.
    These control blocks are allocated on a 1MB boundary and 1MB
    of control blocks can cover 6656 page buffers. To maximize the
    use of control blocks and avoid waste of fixed storage, DB2
    only allocates fixed storage for a PGFIX=YES buffer pool if
    VPSIZE is 6656 or greater.
    

Problem conclusion

  • DB2 has enhanced buffer pool allocation logic to use fixed
    storage for a PGFIX=YES buffer pool when the buffer storage is
    at least 1MB. For example, for a 4K buffer pool to use
    1MB fixed storage, the VPSIZE needs to be at least 256.
    

Temporary fix

  • *********
    * HIPER *
    *********
    

Comments

APAR Information

  • APAR number

    PI12512

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2014-02-25

  • Closed date

    2014-04-23

  • Last modified date

    2014-06-03

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

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

    UI17304

Modules/Macros

  • DSNB1ABS
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UI17304

       UP14/05/09 P F405 ½

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.



Document information

More support for: DB2 for z/OS

Software version: A10

Reference #: PI12512

Modified date: 03 June 2014


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