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JES2 Performance issues




Activating Trace 17 for JES2 Checkpoint Performance analysis:

Trace 17 have  statistics associated with checkpoint performance. Trace records include values for each phase of the checkpoint cycle.

Activating the traces using MVS JES2 Commands:

There are various ways to start TRACE(17) for JES2 Performance analaysis, this section only details activating Trace 17 using commands, for more information regarding this and other methods for Jes z/OS 2.2  see: {+}https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.2.0/com.ibm.zos.v2r2.hasa700/xtrace.htm+.
Information extracted from: {+}https://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/FLASH10009+
Turn on $TRACE(17) records for ten to fifteen minutes during your most active time of the day from a JES2 perspective. This may be during peak TSO activity, when many jobs are submitted, when JES2 queues are longest, or during a JES2 restart. 

  • Sample JES2 operator commands to start Trace 17 under Class A:  

    $S TRACE(17)
    $T TRACEDEF,TABLES=20
    $T TRACEDEF,ACTIVE=Y,LOG=(START=Y,CLASS=A,SIZE=92000)


  • To deactivate Traces after collection:   

    $T TRACEDEF,ACTIVE=NO,SPIN
    $P TRACE(17)


  • Write the Traces to disk from Class A:   

    S XWTR.X,UNIT=SYSDA,DSNAME=JES2.TROUT,SPACE=(CYL,(1,3))
    F X,CLASS=A


  • Analyse Traces using the sample program  JES2T17A provided with JES2



JES2 v2r2 Self Tuning Commands


  • New Function - automatic checkpoint cycle management 
    • Adjust HOLD= and DORMANCY based on workload
    • Users can display whether Cycle Management is automatic or manual, without setting any values
  • SDSF MAS display shows what members are using
    • Adjusts as members join and leave MAS
    • Command to display MAS definitions: 

      $DMASDEF
  • To enable automatic checkpoint cycle management:  

    $T MASDEF,CYCLEMGT=AUTO 
    • This setting gas MAS scope and persists until it is explicitly disabled.

  • The function can also be enabled via MASDEF initialisation statement
  • To disable automatic cycle management, i.e. traditional manual cycle management:  

    $TMASDEF,CYCLEMGT=MANUAL

    All members will revert to the setting previously active (before automatic cycle management was turned on)