PH13562: REORG UTILITY TAKING LONGER WHEN USING DB2SORT VS DFSORT BECAUSEOF LOWER DEGREE OF PARALLELISM

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The customer is running a REORG utility on a partitioned
  tablespace with 731 partitions an 8 indexes .
  When using Db2Sort as sort product the job takes longer elapsed
  time and using more CPU than the case when using DFSort.
  This happens because in the Db2sort case there are less parallel
  tasks started by the Reorg utility.
  This happens because of db2sort memory requirement calculation
  below the 16Mb line that is no longer necessary and can be
  removed.
  This will enable more below the line virtual storage to be
  exploited by the utility job, this increasing the degree of
  parallelism.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Db2 11 for z/OS and Db2 12 for z/OS      *
  *                 users of REORG TABLESPACE utility with       *
  *                 Db2 Sort                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Improve below the line virtual memory   *
  *                      calculation for subtasking parallelism  *
  *                      of REORG TABLESPACE with Db2 Sort       *
  ****************************************************************
  * RECOMMENDATION: Apply corrective PTF when available          *
  ****************************************************************
  This APAR improves the below the line virtual memory calculation
  for REORG TABLESPACE execution using Db2 Sort.  In particular,
  the degree of parallelism calculation for Db2 Sort in REORG
  TABLESPACE eliminated an unnecessary cushion previously reserved
  for storage fragmentation.  This enables maximal use of the
  below the line virtual memory and has a potential to enable a
  higher degree of sort parallelism in REORG compared to before.
  

Problem conclusion

• Code has been modified to improve the below the line virtual
  memory calculation for REORG TABLESPACE execution with Db2 Sort.
  

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:

  UI64496 UI64499

Modules/Macros

•    DSNURPCT
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI64499

     UP19/08/15 P F908

• RC10 PSY UI64496

     UP19/08/14 P F908

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.