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PI31459: MANY DSNT501I AND DSNT376I FOR INDEX CLEANUP DAEMON

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Quite a number of dsnt376i / dsnt501i  messages were being
    received, involving the index clean-up daemon thread when it
    timed out. It doesn't seem to be necessary to externalize
    this information.
    Messages were of the kind:
    DSNT376I  -DSN  PLAN=IDAEMK WITH
            CORRELATION-ID=014.IDAEMKxx
            CONNECTION-ID=DSN
            LUW-ID=xxxxxxxx.xxxxxxxx.xxxxxxxxxxxx
            THREAD-INFO=
    SOPR:..................:................:.......................
    .....
    ....:*:*  :*:*
            IS TIMED OUT. ONE HOLDER OF THE RESOURCE IS
    ..
    DSNT501I  -DSN  DSNILMCL RESOURCE UNAVAILABLE
               CORRELATION-ID=014.IDAEMKxx
               CONNECTION-ID=DSN
               LUW-ID=xxxxxxxx.xxxxxxxx.xxxxxxxxxxxx=0
               REASON 00C9008E
               TYPE 00000D01
               NAME 00000nnn.0000nnnn
    Additional keywords: timeout , time out , rc00C9008E , IDAEMK .
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All DB2 11 for z/OS users using indexes.     *
    ****************************************************************
    * PROBLEM DESCRIPTION: Index pseudo delete cleanup processing  *
    *                      may encounter lock timeouts and issue   *
    *                      many DSNT376I and DSNT501I messages.    *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    An index pseudo delete cleanup thread needs to acquire DBD lock
    and table lock before updating the index to remove the pseudo
    deleted entries. If the required locks have already been held by
    other applications, index pseudo delete cleanup thread could
    timeout and issue many DSNT376I and DSNT501I messages. Because
    index pseudo delete cleanup threads tend to give other
    applications higher priority, normally they are the victims in
    the timeout situation. Index pseudo delete cleanup threads are
    designed to run in the background and to not block other
    applications, issuing a large amount of timeout messages. This
    can be alarming to the users while there is no real contention
    in the system.
    

Problem conclusion

  • DB2 code has been changed to not issue DSNT376I and DSNT501I
    messages if an index pseudo delete cleanup thread timed out
    while waiting for the necessary locks in order to remove the
    pseudo deleted entries from an index. If, however, the index
    pseudo delete cleanup threads are the lock holders and caused
    other applications to timeout, DSNT376I and DSNT501I messages
    will continue to be issued.
    Additional keywords: MSGDSNT501I MSGDSNT376I INDEXDAEMON
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI31459

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2014-12-12

  • Closed date

    2015-04-08

  • Last modified date

    2016-01-21

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

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

    UI26612

Modules/Macros

  •    DSNILMCL DSNTLSUS
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RB10 PSY UI26612

       UP15/04/23 P F504

Fix is available

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Document Information

Modified date:
06 May 2020