IT05114: SLOW PERFORMANCE WHEN TARGET POOL IS COLLOCATED BY GROUP

APAR status

• Closed as program error.

Error description

• When the target storage pool is collocated by group, any
  allocations into that storage pool may have slow performance.
  The majority of time
  is spent on DB2 Reg Exec operations. The number of this DB2
  operations for each aggregate is equal to the number of nodes
  in the same collocation group. If the number of nodes in the
  collocation group is large, the number of DB2 Reg Exec is large
  which causes performance degradation.
  
  This will affect any process that allocates data into a storage
  pool which includes: backup, archive, move data, migration,
  reclamation, backup stgpool.
  
  The following call stack is a sample call stack for this issue:
  
  Thread 123831, Parent 302: psSessionThread, Storage 8286618,
  AllocCnt
  38408 HighWaterAmt 15027091
  
   tid=3d7b7, ptid=322e, det=1, zomb=0, join=0, result=0,
  sess=80719
    Stack trace:
  
      0x090000000010b0c4 recv
  
      0x0900000019a55574
  
  tcprecv__FP17SQLCC_COMHANDLE_TiPcT2UsT5P21SQLCC_TCPCONNHANDLE_TP
  12SQLCC
  COND_TUiPi
  
      0x0900000018c362cc
  
  sqlcctcprecv__FP17SQLCC_COMHANDLE_TP12SQLCC_COND_T
  
      0x090000001994b3d4 sqlccrecv
  
      0x090000001966be74 sqljcReceive__FP10sqljCmnMgr
  
      0x0900000019636afc
  
  sqljrDrdaArOpen__FP14db2UCinterfaceP15db2UCCursorInfo
  
      0x0900000019592080
  csmOpen__FP14db2UCinterfaceP15db2UCCursorInfo
      0x09000000195925c8
  
  CLI_sqlOpen__FP17CLI_STATEMENTINFOP19CLI_ERRORHEADERINFO
  
      0x090000001964a114
  
  SQLExecute2__FP17CLI_STATEMENTINFOP19CLI_ERRORHEADERINFO
  
      0x0900000019646cd8 SQLExecute
  
      0x0000000100136d40 tbRegExecEx
  
      0x00000001009c2148 ExtractVolidFromRegisteredSQL
  
      0x00000001009c156c GetIncludeVolListEx
  
      0x00000001009bdbdc GetIncludeVolList
  
      0x00000001009bb390 AfAllocSpace
  
      0x00000001009baecc AfCreate
  
      0x0000000100603e98 CreateBitfile
  
      0x000000010060127c bfCreate
  
      0x0000000100787c44 CreateBitfile
  
      0x0000000100764088 SmDoBackInsNormEnhanced
  
      0x000000010075a0b4 SmNodeSession
  
      0x000000010074bf24 HandleNodeSession
  
      0x000000010073d934 smExecuteSession
  
      0x0000000100167c98 psSessionThread
  
      0x000000010000cae0 StartThread
  
  Note that the thread name and the bottom part of the call stack
  can be completely different, the important part of the call
  stack is:
  
      0x00000001009c2148 ExtractVolidFromRegisteredSQL
  
      0x00000001009c156c GetIncludeVolListEx
  
      0x00000001009bdbdc GetIncludeVolList
  
      0x00000001009bb390 AfAllocSpace
  
  This is showing that we are getting a list of candidate volumes
  for an allocation request into the storage pool.
  
  In addition, the following can be seen in the performance data
  for this thread:
  
  DB2 Reg Exec     1033 1533.638    1.485    0.000  508.607
  
  The number of DB2 Reg Exec should be a small multiple of the
  number of volume allocation requests that this thread made in
  this snapshot interval.  In this case we can see the value is
  significantly larger.
  
  Tivoli Storage Manager Versions Affected:
  Tivoli Storage Manager Server v7.1
  
  Initial Impact:
  Medium
  
  Additional Keywords:
  TSM; migrate
  

Local fix

• Local Fix:
  Turn off collocation of target pool
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Tivoli Storage Manager server users.                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See ERROR DESCRIPTION.                                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply fixing level when available. This                      *
  * problem is currently projected to be fixed                   *
  * in level 7.1.3. Note that this is subject                    *
  * to change at the discretion of IBM.                          *
  ****************************************************************
  

Problem conclusion

• This problem was fixed.
  Affected platforms: AIX, HP-UX, Solaris, Linux and Windows.
  

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

  TSM SERVER

• Fixed component ID

  5698ISMSV

Applicable component levels

• R71A PSY

     UP

• R71H PSY

     UP

• R71L PSY

     UP

• R71S PSY

     UP

• R71W PSY

     UP