PM99599: /ERE FAILS U0005 DFS0738I MISSING BLOCK ON IMS LOG AFTER SYSTEM HANGS SUBSEQUENT TO A /SWI WADS WHICH FAILED DUE TO I/O ERROR.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The following scenario resulted in /ERE failure:
  /SWI WADS
  I/O during open of one WADS of new WADS pair
  DFS3261I WRITE AHEAD DATA SET NOW ON DFSWADS0 IMLC
  DFS0414I PERMANENT I/O ERROR ON DFSWADS\ - DURING LOG WRITE 48
  DFS3261I WRITE AHEAD DATA SET NOW ON DFSWADS1 IMLC
  DFS3262I NO DATA SET AVAILABLE FOR LOG WRITE AHEAD IMLC
  DFS3273I UNABLE TO PROCESS SWI COMMAND FOR DFSWADS0, REASON 03
  DFS3261I WRITE AHEAD DATA SET NOW ON DFSWADS2 IMLC
  IMS reverts to original WADS pair (2,3) but then hangs and is
  modified out.
  /ERE failed U0005:
  DFS0738I  MISSING BLOCK ON IMS LOG    DDNAME=DFSWADS2
  DFS0738I  LOG TERMINATION FAILED FOR  DDNAME=DFSOLP09
  DFS0738I  MISSING BLOCK ON IMS LOG    DDNAME=DFSWADS2
  DFS0738I  LOG TERMINATION FAILED FOR  DDNAME=DFSOLP09
  DFS0738I  LOG TERMINATION FAILED FOR  DDNAME=DFSOLS09
  DFS0738X ERROR TERMINATING OLDS    RC=06  DDNAME=DFSWADS2
  DFS0738I  LOG TERMINATION FAILED FOR  DDNAME=DFSOLS09
  The OLDS was closed by Log Buffer Purge at abend, but it failed
  to purge the current buffer, which contained data already
  written to the WADS. Purge added two records - a x'48' pad
  record and a x'06' STAE CLOSED record, but this duplicated
  two LSNs already on WADS. This caused the restart failure.
  It appears the I/O during OPEN of first WADS of new pair
  caused us to clear information tracking the current log buffer
  to WADS utilization, and caused PURGE to miss the last 96
  records in the current log buffer.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All IMS V13 users                            *
  ****************************************************************
  * PROBLEM DESCRIPTION: Restart fails with ABENDU0005 RC06      *
  *                      after IMS gets post code 48 on new      *
  *                      WADS during /SWITCH WADS, hangs,        *
  *                      and is cancelled.                       *
  ****************************************************************
  * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
  ****************************************************************
  IMS gets an error opening a new WADS during processing of a
  /SWITCH WADS command.  There are no other available WADS so IMS
  reverts to the original WADS.  If IMS then fails before it
  can write to etiher the OLDS or WADS, the subsequent restart
  may fail with ABENDU0005 RC06.
  

Problem conclusion

• GEN:
  POSTREQ PI41850
  POSTREQ PI48968
  POSTREQ PI54890
  KEYWORDS:
  
  *** END IMS KEYWORDS ***
  IMS prepares to switch WADS by obtaining the log latch
  exclusively and attempting to flush any unhardened log data to
  the current WADS.  The attempt fails because the checkwrite
  target values are not set, and checkwrite processing regards
  the AWE as a fulfilled request.  This leaves IMS vulnerable to
  two problems.
  
  First, although it prevents WADS I/O after that point, it does
  not ensure that there is no I/O in progress.  Switching the WADS
  involves use of the same file structures used to write to the
  WADS and their use must be serialized.  I/O that is in progress
  when the current WADS is closed will be purged with post code
  48.  If this is seen after the next WADS is opened, the error
  will be reported for the next WADS and a post for later WADS I/O
  may be lost.
  
  Second, if IMS reverts to the original WADS and then fails,
  buffer purge may overwrite some but possibly not all of the
  data in the original WADS.  A subsequent restart will fail with
  ABENDU0005 RC06.
  
  DFSFLLG0 has been changed so that preparation for switching
  WADS will flush any unhardened data to the WADS with an AWE
  that has the current block sequence number and data offset
  correctly set.  It will additionally force the same data to the
  OLDS so that WADS data in the WADS being switched from cannot
  be lost.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

• REPINNED RP15/06/05 (ATXT) TO ADD POSTREQ PI41850 INFO.
   **** PE15/06/05 PTF IN ERROR. SEE APAR PI41850 FOR DESCRIPTION
  ×**** PE15/06/05 FIX IN ERROR. SEE APAR PI41850  FOR DESCRIPTION
  REPINNED RP15/09/18 (ATXT) TO ADD POSTREQ PI48968 INFO.
         **** PE15/09/18 PTF IN ERROR. SEE APAR PI48968 FOR
  DESCRIPTION
  ×**** PE15/09/17 FIX IN ERROR. SEE APAR PI48968  FOR DESCRIPTION
  REPINNED RP16/04/04 (ATXT) TO ADD POSTREQ PI54890 INFO.
   **** PE16/04/04 PTF IN ERROR. SEE APAR PI54890 FOR DESCRIPTION
  

APAR Information

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

  PM99408

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

  UI12363

Modules/Macros

•    DFSFLLG0
  

Fix information

• Fixed component name

  IMS V13

• Fixed component ID

  5635A0400

Applicable component levels

• R300 PSY UI12363

     UP13/11/12 P F311 Ž

Fix is available

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