PH38891: MQ Z/OS: CHINIT INITIALIZATION DOES NOT COMPLETE DUE TO WAITING FOR THE SYSZTIOT ENQ WHEN THERE IS AN OUTSTANDING TAPE MOUNT

APAR status

• Closed as program error.

Error description

• If queue manager startup has an outstanding tape mount for a
  log archive, START CHINIT does not complete and the listeners
  do not start until the outstanding tape mount is satisfied or
  cancelled.
  
  This is similar to the situation in APAR PH23328.
  
  Recreate scenario:
  1. Use CSQ6ARVP or SET ARCHIVE to specify a tape UNIT
  2. Disable tape activity to make tapes unavailable
  3. Recall some migrated datasets to force HSM to be very busy
  4. Force an archive with the ARCHIVE LOG command
  5. Verify that the offload task is busy by using the DISPLAY
  LOG command:
       CSQJ370I !CSQ1 LOG status report ...
  
       Copy %Full zHyperWrite Encrypted DSName
  
        1      1  NO          YES       hlq.LOGCOPY1.DS04
  
        2      1  NO          YES       hlq.LOGCOPY2.DS04
  
       Restarted at <date, time> using RBA=<rba value>
       Latest RBA=<rba value>
  
       Offload task is BUSY, allocating archive data set
  
       Full logs to offload - 2 of 12
  6. Cancel the queue manager
  7. Restart the queue manager
        IEF244I CSQ1MSTR CSQ1MSTR - UNABLE TO ALLOCATE 1 UNIT(S)
                AT LEAST 1 OFFLINE UNIT(S) NEEDED.
  
        IEF877E CSQ1MSTR NEEDS 1 UNIT(S)
          FOR CSQ1MSTR SYS00013
  
          LIBRARY: <libaray>   LIBRARY STATUS: ONLINE
  
          OFFLINE
          ...
        IEF878I END OF IEF877E FOR CSQ1MSTR CSQ1MSTR SYS00013
  
       *nnnn IEF238D CSQ1MSTR - REPLY DEVICE NAME OR 'CANCEL'.
  
        CSQY022I !CSQ1 QUEUE MANAGER INITIALIZATION COMPLETE
  
  
  The queue manager completes initialization, but the CHIN does
  not.
  
  A dump was captured at the time of the hang. IPCS ANALYZE
  RESOURCE shows that one TCB for the CSQ1MSTR job holds
  MAJOR=SYSZTIOT, and a different TCB for the MQ command
  processor requires it.  The waiting ENQ is due to an OPEN for
  the CSQOUT2 DD by CSQNRRWO.
  
  Additional keywords:
  CHIN start up wait hang hung GRS contention
  

Local fix

• Resolve the tape mount request if possible
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: SYSZTIOT contention causes the command  *
  *                      server to hang during channel initiator *
  *                      startup.                                *
  ****************************************************************
  During startup a log offload is outstanding so CSQJOFF1 is
  called to offload the logs. The required tape drive is offline
  so the offload task is suspended in DYNALLOC processing waiting
  for the device, while holding the SYSZTIOT ENQ.
  
  When the channel initiator is started from CSQINP2, the
  startup completion message is written to the CSQOUT2 DD, however
  as this can occur after the initialisation server has finished
  processing all commands in CSQINP2, the message is written by
  the command server, which will open a new DCB for CSQOUT2.
  
  This ?OPEN hangs because it requires the SYSZTIOT ENQ, resulting
  in the command server hanging until the ENQ is available.
  

Problem conclusion

• Queue manager startup processing is changed to cache the DCB
  for CSQOUT2, allowing 'late' responses to be written to this
  DD without requiring the SYSZTIOT ENQ.
  

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:

  UI80142

Modules/Macros

• CSQNINE1 CSQNINS  CSQNRRWO
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels