IT14336: SERVER DATABASE BACKUP PERFORMANCE AFFECTED BY DB2 FLUSH ACTIVITY AS MANAGED WITH OPTIONS SOFTMAX AND PAGE_AGE_TRGT_MCR

7.1.6.000-TIV-TSMSRV-Linuxs390x
7.1.6.000-TIV-TSMSRV-Linuxppc64
7.1.6.000-TIV-TSMSRV-WIN
7.1.6.000-TIV-TSMSRV-SolarisSPARC
7.1.6.000-TIV-TSMSRV-Linuxx86_64
7.1.6.000-TIV-TSMSRV-HP-UX
7.1.6.000-TIV-TSMSRV-AIX
IBM Spectrum Protect Server V7.1 Fix Pack 6 (7.1.6.000) Downloads

APAR status

• Closed as program error.

Error description

• Database backup can encounter performance issues when DB2 is
  waiting to flush the dirty pages from the DB2 buffer pool. When
  this issue occurs, the database backup will be slow in starting
  the $$_TSMDBMGR_$$ sessions or a QUERY PROCESS after the
  sessions have started will not show any progress.. For example,
  QUERY PROCESS output:
  
  Process  Process Description  Process Status
  Number
  -------- -------------------- -----------------------------
  
  2,087    Database Backup      TYPE=FULL in progress. Bytes
                                backed up:
                                768 GB. Current output
                                volume(s):500193L4.
  
  The Bytes backed up will not change for a long time, could be
  hours. The process look hung. The hang can occur anytime during
  the operation, but it will eventually continue after some amount
  of time.
  
  In depth db2 analysis has revealed that the database backup
  processing is waiting for DB2 buffer pool flushes to complete
  before it can proceed. To expedite the flush activity the DB2
  option page_age_trgt_mcr can be used to specify how long the
  changed pages remain in the DB2 buffer pool. This option can
  only be used if the DB2 SOFTMAX value is set to zero. Because
  the server code currently does not allow for the SOFTMAX value
  to be set to zero this APAR is being taken to change to server
  to allow the zero setting. Once this is the case the default
  page_age_trgt_mcr value of 240 be used and the need the database
  backup to wait for buffer pool flushes should be reduced.
  
  Tivoli Storage Manager Versions Affected:
  All supported IBM Spectrum Protect server
  Tivoli Storage Manager server 7.1
  
  Customer/L2 Diagnostics (If Applicable)
  To determine if the customer is affected by this APAR, the
  servermon script should be run for the entire duration of the DB
  backup. The files created by servermon ending in "db2pd.txt"
  need to be examined, looking for the section titled
  "Bufferpool: 2 ".  This section shows the count of the number of
  "dirty pages" needing to be flushed to disk before the backup
  can begin or proceed. If the customer is affected by this APAR,
  then Bufferpool 2 will show thousands of pages needing to be
  flushed before the $$_TSMDBMGR_$$ sessions can begin. Also, If
  the DB backup appears to stall or hang in the middle of the
  backup, then this section will show thousands of pages needing
  to be flushed before the backup can proceed again. The output
  will look like:
  Bufferpool: 2
      Dirty pages %       : 726383 / 8406224 (8.64% dirty)np
  
  Initial Impact:
  Low
  
  Additional Keywords:
  TSM backup db slow
  

Local fix

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 7.1.6. 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