PM93375: PERFORMACE ELPASED TIME DEGRADATION AND INCREASED SYNCH I/O IN PARALLEL INDEX UPDATES.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Performace elpased time degradation and increased synch I/O in
    parallel index updates. Also, parallel index updates appear to
    be either reduced significantly or disabled in V11.    (d167833)
    Additional symptoms: 04E 00C20223 ABENDS0C4 S0C4 0C4
    

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: DB2 V11 users.                               *
    ****************************************************************
    * PROBLEM DESCRIPTION: Performance degradation caused by       *
    *                      parallel index updates performing       *
    *                      synchronous reads.                      *
    *                                                              *
    *                      In data sharing, ABEND04E RC00C20223    *
    *                      in DSNB5ULK, or ABEND0C4 in DSNB5PCO.   *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Parallel index updates may perform excessive synchronous reads
    due to the setting of a "no prefetch" flag which is incorrectly
    applied to the processing of a conditional GetPage request.
    
    The DSNB5ULK and DSNB5PCO abends may occur when a castout engine
    is performing parallel I/Os, and the ROB which was designated
    for the wait for the first I/O is reused for another wait.
    

Problem conclusion

  • The conditional GetPage logic has been modified to schedule the
    prefetch of the requested page when it is not already in the
    buffer pool, regardless of the setting of the "no prefetch"
    flag.
    
    The castout logic has been modified to allocate a separate ROB
    to be used for the wait for the first I/O, rather than using
    the CTBMROB for this purpose.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM93375

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-07-18

  • Closed date

    2013-09-17

  • Last modified date

    2013-11-04

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

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

    UK97639

Modules/Macros

  • DSNB1GET DSNB5PCO
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RB10 PSY UK97639

       UP13/10/03 P F310

Fix is available

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Document information


More support for:

DB2 for z/OS

Software version:

B10

Reference #:

PM93375

Modified date:

2013-11-04

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