IT28165: DB2 PURESCALE INSTANCE MAY PANIC DURING BUFFERPOOL DECREASE

APAR status

• Closed as program error.

Error description

• A pureScale instance may panic while a bufferpool decrease
  operation is running. Bufferpool decrease can be initiated from
  STMM or by explicitly resizing a bufferpool to a smaller size.
  This is a very rare timing issue and the likelihood to hit the
  issue is very low. The panic will be reported by an agent
  indicating that a page latch is not held, similar to the
  following db2diag.log message:
  
  FUNCTION: DB2 UDB, SQO Latch Tracing,
  SQLO_SLATCH_CAS64::releaseConflict, probe:330
  MESSAGE :
  ZRC=0x870F011E=-2029059810=SQLO_LATCH_ERROR_EXPECTED_HELD
            "expected latch to be held."
  CALLED  : OS, -, unspecified_system_function
  DATA #1 : String, 39 bytes
  Attempting to unlock an invalid latch:
  DATA #2 : File name, 16 bytes
  sqloLatchCAS64.C
  DATA #3 : Source file line number, 8 bytes
  1054
  DATA #4 : Codepath, 8 bytes
  2
  DATA #5 : String, 125 bytes
  0x0000000000000000: {
     held X: 0
     reserved for X: 0
     shared holders: 0
     firstSharIndex: 0x0
     firstExclIndex: 0x0
  }
  DATA #6 : LatchMode, PD_TYPE_LATCH_MODE, 8 bytes
  0x0 (invalid mode)
  DATA #7 : String, 399 bytes
  {
     state         = 0x0000000000000000
                   = {
                         held X: 0
                         reserved for X: 0
                         shared holders: 0
                         firstSharIndex: 0x0
                         firstExclIndex: 0x0
                     }
     starve X mode = false
     xWaitCount    = 0
     requestCount  = 0
     identity      = SQLB_BPD::bpdLatch_SX (264)
  }
  DATA #8 : Pointer, 8 bytes
  0x0a000302d59785d8
  
  The latch information in the trap file in the FODC directory
  will indicate the agent is holding a page latch in mode: S.
  
  <LatchInformation>
  Holding Latch type: (SQLO_LT_SQLP_SAVEPOINTS__spLatch) -
  Address: (0xa000301836b8680)
  Holding Latch type: (SQLO_LT_SQLP_TENTRY__applLatch) - Address:
  (0xa000301836b8cf0), Line: 873, File: sqlpxreg.C HoldCount: 1
  Holding latch type: (SQLO_LT_SQLB_BPD__bpdLatch_SX) - Address:
  (0xa0003031e7e9968), mode: S, Line: 1650, File: sqlbfix.C
  </LatchInformation>
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 11.1 Mod 4 Fixpack 5
  

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:

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RB10 PSN

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