PI41127: DSNISMRT 0C17 ABEND WAS ISSUED AFTER LOCK ESCALATION OF RLL TABLESPACE IN V11

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• This problem only exists in V11 and only row level locking
  tablespace is affected.
  
  Locking a row for insert resulted in lock escalation. Before the
  lock request, insert position in the page had been determined.
  lock escalation thread was waiting for other threads to release
  the locks on the involved object.
  
  Other threads tried to request more locks and deadlocked with
  lock escalation thread. other threads started to rollback.
  The original insert position was no longer valid after the
  rollback of other threads.
  
  After escalation, the page latch was reacquired, and the insert
  was attempted at the original position while it's no longer
  valid. Page was broken after the insert.
  
  Later, page compaction exposed the problem and led to DSNISMRT
  0C17 abend.
  

Local fix

• either alter locksize to page or alter LOCKMAX to avoid
  lock escalation.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: DB2 11 for z/OS users of non segmented       *
  *                 table space with row level locking           *
  ****************************************************************
  * PROBLEM DESCRIPTION: ABEND04E RC00C90105 at DSNISMRT ERQUAL  *
  *                      0C17 during insert.                     *
  *                                                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  If lock esclation happened during insert execution, DB2 needs to
  release x page latch it held before gross lock acquiring. And
  relatch the page after gross lock acquired. If the page is
  detected changed, DB2 will drive page checking from scratch to
  make sure of data integrity.
  But for row level locking non segmented table space, DB2 11 for
  z/OS failed to check if the page is changed by other threads
  after relatchingthe page. So, data loss could happen.
  

Problem conclusion

• DB2 code has been modified to make sure non segmented table
  space with row level locking will check page change properly
  after lock escalation to avoid the data loss.
  

Temporary fix

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

Comments

APAR Information

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

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

  UI29844

Modules/Macros

• DSNISMRT
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI29844

     UP15/08/14 P F508

Fix is available

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