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

Obtain the fix for this APAR.

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 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

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