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PM74803: ENABLING APAR FOR THE PORTION OF APAR PM69760 THAT DEALS WITH SCA REBUILD TIMEOUT WHILE MAINLINE DBET UPDATE IS IN NOTIFY EXIT

A fix is available

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APAR status

  • Closed as program error.

Error description

  • This is the enabling APAR for a portion of APAR PM69760.
    ...
    For the timing window when the SCA REBUILD tries to obtain the
    DBET hash lock while a mainline DBET updater is in the notify
    exit path, the SCA REBUILD timeout will not be resolved until
    this enabling APAR, which should be applied only after
    APAR PM69760 has been applied on all data sharing members.
    ...
    The preconditioning APAR PM69760 still fixes major scenarios
    of the SCA REBUILD timeout so it still has significant value
    even before the enabling APAR is applied.
    ...
    The following sample illustrates the SCA REBUILD timeout:
    ---------------------------------------------------------
    DSNT376I  - PLAN=BCT      WITH 398
            CORRELATION-ID=014.RBDBET01
            CONNECTION-ID=V91A
            LUW-ID=DSNCAT.SYEC1DB2.CA3071BF1397
            THREAD-INFO=SYSOPR:*:*:*
            IS TIMED OUT. ONE HOLDER OF THE RESOURCE IS PLAN=
    WITH
            CORRELATION-ID=020.JOBSTO07
            CONNECTION-ID=V91A
            LUW-ID=DSNCAT.SYEC1DB2.CA3071B10954=7
            THREAD-INFO=SYSOPR:*:*:*
            ON MEMBER V91A
    
    DSNT501I  - DSNILMCL RESOURCE UNAVAILABLE 399
               CORRELATION-ID=014.RBDBET01
               CONNECTION-ID=V91A
               LUW-ID=DSNCAT.SYEC1DB2.CA3071BF1397=0
               REASON 00C900C0
               TYPE 00002105
               NAME INTERNAL LOCK 05
    
    DSN7504I  - DSN7LST2 400
    SCA STRUCTURE DSNCAT_SCA REBUILD UNSUCCESSFUL. REASON CODE =  8.
    
    IXC522I REBUILD FOR STRUCTURE 401
    DSNCAT_SCA IS BEING STOPPED
    TO FALL BACK TO THE OLD STRUCTURE DUE TO
    CONNECTOR SPECIFIC REASON
     USER CODE: 00000008
    
    IXC521I REBUILD FOR STRUCTURE DSNCAT_SCA 405
    HAS BEEN STOPPED
    ----------------------------------------------------------------
    .
    Exposure if the enabling APAR PM74803 were to be applied on any
    member before applying the preconditioning APAR PM69760:
    The exposure is that if SCA REBUILD is running and there is a
    concurrent DBET activity (e.g. a utility running on a member
    without the enabling APAR PM74803 and turning on UTRW), members
    that have the enabling APAR on might ignore the notify to turn
    on an exception state for an object. So members in the group
    could get out of synch between each other with regard to a DBET
    state - some will have it turned on, some won't, which could
    lead to allowing access to the object when it should be
    protected by DBET state. However, this chance for inconsistency
    is only if there is SCA REBUILD running and only if the member
    that has the enabling APAR on isn't the one driving the DBET
    activity (and therefore originating DBET notifies).
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All DB2 10, DB2 9 and DB2 V8 for z/OS data   *
    *                 sharing users of the z/OS SETXCF REBUILD     *
    *                 command when issued against SCA              *
    ****************************************************************
    * PROBLEM DESCRIPTION: Timeout MSGDSNT376I MSGDSNT501I with    *
    *                      RC00C900C0 TYPE00002105 may occur in    *
    *                      data sharing when a REBUILD of the SCA  *
    *                      structure is issued (e.g.               *
    *                      SETXCF START,REBUILD,STRNM=DSNCAT_SCA), *
    *                      resulting in stoppage of the rebuild,   *
    *                      with messages MSGDSN7504I, MSGIXC522I   *
    *                      and MSGIXC521I, caused by concurrent    *
    *                      mainline DBET updater that happens to   *
    *                      be in the notify exit path              *
    *                                                              *
    *                      (PM74803 is the enabling APAR for a     *
    *                      portion of APAR PM69760's code.)        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    REBUILD of the SCA structure may experience a timeout on
    resource type 00002105 when running concurrently with
    database exception table (DBET)-heavy activity such as during
    utility workloads that turn on/off various DBET states like
    UTRW, RBDP etc.
    
    The following sample illustrates the issue:
    ----------------------------------------------------------------
    DSNT376I  - PLAN=BCT      WITH 398
            CORRELATION-ID=014.RBDBET01
            CONNECTION-ID=V91A
            LUW-ID=DSNCAT.SYEC1DB2.CA3071BF1397
            THREAD-INFO=SYSOPR:*:*:*
            IS TIMED OUT. ONE HOLDER OF THE RESOURCE IS PLAN=
    WITH
            CORRELATION-ID=020.JOBSTO07
            CONNECTION-ID=V91A
            LUW-ID=DSNCAT.SYEC1DB2.CA3071B10954=7
            THREAD-INFO=SYSOPR:*:*:*
            ON MEMBER V91A
    
    DSNT501I  - DSNILMCL RESOURCE UNAVAILABLE 399
               CORRELATION-ID=014.RBDBET01
               CONNECTION-ID=V91A
               LUW-ID=DSNCAT.SYEC1DB2.CA3071BF1397=0
               REASON 00C900C0
               TYPE 00002105
               NAME INTERNAL LOCK 05
    
    DSN7504I  - DSN7LST2 400
    SCA STRUCTURE DSNCAT_SCA REBUILD UNSUCCESSFUL. REASON CODE =  8.
    
    IXC522I REBUILD FOR STRUCTURE 401
    DSNCAT_SCA IS BEING STOPPED
    TO FALL BACK TO THE OLD STRUCTURE DUE TO
    CONNECTOR SPECIFIC REASON
     USER CODE: 00000008
    
    IXC521I REBUILD FOR STRUCTURE DSNCAT_SCA 405
    HAS BEEN STOPPED
    ----------------------------------------------------------------
    
    The reason for the timeout of the SCA REBUILD is that a mainline
    DBET updater (e.g. a utility) is suspended (while holding the
    DBET hash lock) by the SCA REBUILD process. When the SCA REBUILD
    tries to obtain the same lock, it cannot do so because the
    holder is suspended and therefore the SCA REBUILD times out.
    
    APAR PM74803 is particularly for the timing window when the SCA
    REBUILD tries to obtain the DBET hash lock while a mainline DBET
    updater is in the notify exit path.
    

Problem conclusion

  • Code has been changed to adjust the serialization scheme
    between mainline DBET updaters and the SCA REBUILD process.
    
    APAR PM74803 is the enabling APAR for a portion of APAR PM69760.
    APAR PM74803 should be applied only after APAR PM69760 has been
    applied on all data sharing members.
    
    Additional keywords: DB2DSHR SYSPLEXDS
    

Temporary fix

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

Comments

  • ž**** PE13/06/20 PTF IN ERROR. SEE APAR PM91546  FOR DESCRIPTION
    

APAR Information

  • APAR number

    PM74803

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    910

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-10-11

  • Closed date

    2013-01-09

  • Last modified date

    2013-08-10

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

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

    UK90830 UK90831 UK90832

Modules/Macros

  • DSNIDBEL DSNIDBGN DSNIDBGR DSNIDBNG
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UK90830

       UP13/01/24 P F301

  • R810 PSY UK90831

       UP13/01/24 P F301

  • R910 PSY UK90832

       UP13/01/24 P F301

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

Modified date:
10 August 2013