PH49585: UNNECESSARY DEFINE CHANNEL QSGDISP(COPY) COMMANDS ISSUED DURING CHINIT STARTUP

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• An unnecessary DEFINE CHANNEL() QSGDISP COPY command is issued
  during CHINIT startup:
  
  DEFINE CHANNEL('channel name') CHLTYPE(SVRCONN) QSGDISP(COPY)
  REPLACE
  
  As part of channel initiator startup, the CHINIT supervisor
  task performs channel group object reconciliation. This results
  in the supervisor task PC-ing into the QMGR to routine
  CSQICHLO. This routine finds all of the QSGDISP(GROUP) channel
  objects stored in Db2, and also all of the QSGDISP(COPY)
  objects stored on page set 0. Once it has found all of these
  objects, it compares the contents of the QSGDISP(GROUP) and
  QSGDISP(COPY) object lists to look for any inconsistencies.
  These inconsistencies are then resolved by issuing console
  commands.
  
  For example if a QSGDISP(COPY) of an object is found, but the
  QSGDISP(GROUP) copy of the object is not found, then a DELETE
  CHANNEL() QSGDISP(COPY) console command will be issued. These
  commands are issued by a QMGR service task created by the
  CHINIT supervisor task.
  
  In this case, the CHINIT supervisor task determines that the
  QSGDISP(GROUP) and QSGDISP(COPY) objects are out of sync for
  SVRCONN channel. To rectify this, a DEFINE CHANNEL()
  QSGDISP(COPY) REPLACE command is issued to refresh the
  QSGDISP(COPY) object from the QSGDISP(GROUP) object. The
  QSGDISP(COPY) refresh behaviour is documented in the IBM
  documentation in Table 8:
  
  https://www.ibm.com/docs/en/ibm-mq/9.2?topic=reference-define-ch
  annel-define-new-channel#q085520___qsgdisp
  
  However, in the customer's case, the QSGDISP(GROUP) and
  QSGDISP(COPY) are not actually out of sync. This incorrect
  determination stems from a CLNTCONN channel existing with the
  same name as another SVRCONN channel. The logic which
  determines if a channel object requires refreshing from the
  group object does not always correctly handle two channels with
  the same name. Note that this does not always result in a
  DEFINE CHANNEL command being issued, the problem also depends
  on the positions of the SVRCONN and CLNTCONN channel objects in
  an internal object hash table.
  
  There is no known work around to stop this DEFINE CHANNEL
  command being issued, but this command being issued and failing
  has no adverse affects, so the customer can ignore it for now.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0 and Release 3       *
  *                 Modification 0.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: It is possible for a DEFINE CHANNEL     *
  *                      (...) CHLTYPE(SVRCONN) QSGDISP (COPY)   *
  *                      REPLACE command to be unnecessarily     *
  *                      issued at channel initiator start up.   *
  ****************************************************************
  The DEFINE CHANNEL(...) CHLTYPE(SVRCONN) QSGDISP(COPY) REPLACE
  command was being issued incorrectly due to there being two
  channels with the same name. The channels had different
  types (SVRCONN & CLNTCONN) but the code assigned with keeping
  GROUP and COPY objects in sync did not handle this correctly.
  The code ended up deciding that the copy and group objects were
  out of sync so issued the command to refresh the copy object
  from the group definition incorrectly.
  

Problem conclusion

• The code has been changed to now only issue the DEFINE CHANNEL
  (...) CHLTYPE(SVRCONN) QSGDISP(COPY) REPLACE command when both
  a channel's name and type match the group object definition. As
  a result of this, the command will not be issued for channels
  with the same name if their channel types are different.
  

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:

  UI90678 UI90679

Modules/Macros

• CSQICHLO
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R200 PSY UI90679

     UP23/03/08 P F303

• R300 PSY UI90678

     UP23/03/08 P F303

Fix is available

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