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PH31959: ABND=0C4-00000004 LOC=DSNLILLM.DSNLILOS+00468 WHEN RUNNING CMTSTAT=ACTIVE AND A HIGH RATE OF THREAD TERMINATIONS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • During a high rate of client connection termination
    requests on systems configured with CMTSTAT=ACTIVE,
    ABEND 0C4-00000004 from DSNLILOS at offset +00468
    may lead to DDF termination.
    In the reported case, the DDF resync task was
    taken down with the abend 0C4.
    
    The following messages may be seen
    indicating that DDF is terminating and new
    connections are not being accepted.
    
    
    DSNL033I ssid DSNLTRST
    DDF TERMINATION SCHEDULED DUE TO DETECTION OF
    ABEND 0C4
    REASON 00000000
    
    DSNL030I ssid DSNLAGNT DDF PROCESSING FAILURE FOR
     REASON=00D31032
    
    
    Additional keywords and symptoms:
    ********************************
    DB2 DDF ABND0C4 00C4
    DSNLILOS OFFSET00468
    DSNL033I DSNL030I
    00D31032 RC00D31032
    028.RESYNC01 RESYNC
    

Local fix

  • Start of DDF is required to allow distributed activity
    after DSNL033I message.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All Distributed Data Facility (DDF) users.                   *
    * Especially those who start Db2 with DDF                      *
    * THREADS (DSN6FAC CMTSTAT) set to ACTIVE                      *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * Abend 0C4-00000004 at DSNLILOS+00468                         *
    * with subsequent Db2 messages                                 *
    * DSNL033I and DSNL030I indicating                             *
    * DDF termination due to REASON=00D31032                       *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply corrective PTF when available                          *
    ****************************************************************
    When Db2 is started with a subsystem parameters module (ZPARM)
    that has DDF THREADS (DSN6FAC CMTSTAT) set to ACTIVE, a DBAT
    is allocated and active for a client connection until the
    client connection is terminated. When the number of client
    connections reaches the same number as the current value for
    MAX REMOTE ACTIVE (DSN6SYSP MAXDBAT), any further client
    connections that are accepted due to MAX REMOTE CONNECTED
    (DSN6SYSP CONDBAT) being higher than MAXDBAT will be queued
    waiting for a DBAT slot to become available. A DBAT slot will
    only become available when a client connection using a DBAT is
    terminated. If those client connections which are waiting for
    a DBAT are terminated by their client before a DBAT can be
    allocated for its request processing, there is a possibility,
    due to missing logic in DDF, that the processing to handle the
    client connection loss will be interfered with by the
    processing to allocate a DBAT for the client connection. When
    this situation occurs, an ABEND 0C4-00000004 at DSNLILOS+00468
    will be raised which will then lead to Db2 messages DSNL033I
    and DSNL030I being issued indicating that DDF has terminated
    due to Db2 reascon code 00D31032.
    

Problem conclusion

  • Db2 has been changed to correctly serialize the connection
    loss processing with the processing required to allocate a
    DBAT for use by a client connection when Db2 has been started
    with a subsystem parameters (ZPARM) module with
    DDF THREADS (DSN6FAC CMTSTAT) set to ACTIVE.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PH31959

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2020-11-20

  • Closed date

    2021-01-04

  • Last modified date

    2021-02-01

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

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

    UI73328

Modules/Macros

  • DSNLCTRC
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RC10 PSY UI73328

       UP21/01/14 P F101 ¢

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:
02 February 2021