PI93817: ENHANCE IRLM RELATED INFORMATION IN DB2 STAT COLLECTION

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• Collect IRLM latch contention counters and other system stats in
  DB2 statistics trace.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 for z/OS users requesting IFCID-2                    *
  * trace values for IRLM internal diagnostic                    *
  * statistics.                                                  *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Db2 can only retrieve a small set of                         *
  * IRLM internal stats via SMF trace. In                        *
  * order to view more IRLM diagnostic                           *
  * info, it must be extracted from dumps.                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available.                         *
  ****************************************************************
  IFCID 2 reports Db2 Statistics Records which include Lock
  Manager data and Global Locking data mapped by both QTXA and
  QTGS. Currently, these two control blocks only contain a small
  subset of IRLM internal system stats and counters.
  ********* NEW QTGS Fields *********
  QTGSLCAIC    Active IRLM Control Block latch contention counter
  QTGSDGBL     Total number of global deadlocks
  QTGSLICNT    Local resource contentions
  QTGSGICNT    Global resource contentions
  QTGSGCONT    Visits to the contention exit, but IRLM granted ok
  QTGSFCONT    False contentions
  QTGSCPLOK    Plock Exit counter
  QTGSCNOTY    Notify Exit counter
  ********* NEW QTXA Fields *********
  QTXALCMM     Main latch contention due to Main latch held
  QTXALCMU     Main latch contention due to Use Count not being 0
  QTXALCSM     Secondary latch contention due to Main latch held
  QTXACRLK     Resource Hash Table latch contention for LOCK
  QTXACWLK     Workunit Hash Table latch contention for LOCK
  QTXACRUK     Resource Hash Table latch contention for UNLOCK
  QTXACWUK     Workunit Hash Table latch contention for UNLOCK
  QTXACRCH     Resource Hash Table latch contention for CHANGE
  QTXACWCH     Workunit Hash Table latch contention for CHANGE
  QTXACRNT     Resource Hash Table latch contention for NOTIFY
  QTXACNNT     Notify Control Block latch contention for NOTIFY
  QTXACRCP     Resource Hash Table latch contention for COMPAT
  QTXACWCP     Workunit Hash Table latch contention for COMPAT
  QTXACRAL     Resource Hash Table latch contention for ASYNC LOCK
  QTXACWAL     Workunit Hash Table latch contention for ASYNC LOCK
  QTXACWSY     Workunit Hash Table latch contention for SYNC
  QTXASRCL     Resource latch contention counter
  QTXAUCNT     Use Count counter for Compat Queue Elements
  QTXALCCP     # of Compat QEs generated
  QTXACGEN     Generic latch contentions
  QTXACRQF     Resource Hash Table latch contention for QUERY FAST
  QTXACWQF     Workunit Hash Table latch contention for QUERY FAST
  QTXADLCL     Total number of local deadlocks
  QTXATOUT     Timeout RLBs purged by IRLM
  QTXARTRY     Re-tryable ABENDS in IRLM
  QTXANRTY     Non re-tryable ABENDS in IRLM
  QTXASUSP     Suspend Exit counter
  QTXARSUM     Resume Exit counter
  QTXASTAT     Status Exit counter
  QTXADEAD     Deadlock Exit counter
  QTXATIME     Timeout Exit counter
  

Problem conclusion

Temporary fix

Comments

• Db2 has been enhanced to include additional IRLM statistic
  counters for secondary latch contention and system activity in
  IFCID 2.
  DB2 STAT request to IRLM will collect IRLM system activity
  counters. Additionally, if IRLM APAR PI93819 is also applied,
  the STAT call will also collect IRLM secondary latch contention
  counters.
  ×**** PE18/04/19 PTF IN ERROR. SEE APAR PI97000  FOR DESCRIPTION
  
  *** 18/12/20 *** PI93817 increases the size of the QTXA section
  by 124 bytes. This section is also present in IFCID 3 (plan
  accounting). If this information is collected, this APAR will
  increase the volume of SMF data produced by Db2. If that is a
  concern, using SMFCOMP=YES to mitigate the impact.
  

APAR Information

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

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

  UI54732 UI54738

Modules/Macros

• DSNDQTXA DSNDQTGS DSNTLRST
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI54738

     UP18/04/10 P F804

• RB10 PSY UI54732

     UP18/04/10 P F804

Fix is available

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