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More granular statistics trace data in Db2 12

By Paul McWilliams posted Fri May 01, 2020 02:59 PM

  
By Sharon Roeder and Paul McWilliams.

In Db2 12 after you apply APAR PH18658, you can now collect more granular data for certain key Db2 statistics traces. Before now, these traces were always collected at a fixed one-minute interval. With today's faster processors, monitoring at a more granular interval is necessary for understanding performance peaks and analyzing slow downs. In many cases, clients have reported that suffering 5 to 10 second slowdown in Db2 processing that caused serious impact to a Db2 member, or group wide. 

To control the more granular collection, you can set the value of the new STATIME_MAIN subsystem parameter. You can specify an interval of 5 to 60 seconds, in 5 second increments.  The statistics are always collected at the specified interval starting at second zero of each minute, so for a five second interval, the trace records are written at 1:00, 1:05, 1:10, and so on.

The new STATIME_MAIN setting now controls the interval for  for the following Db2 statistics traces: 

  • 0001 (System statistics)
  • 0002 (Db2 statistics)
  • 0202 (Buffer Pool Attributes)
  • 0225 (Storage statistics)
  • 0230 (Group Buffer Pool Attributes)
  • 0254 (Coupling Facility Cache statistics)
  • 0369 (Wait and CPU time aggregated by connection type)

However, the new STATIME_MAIN setting does not control the interval for the following statistics traces, which remain controlled the existing STATIME subsystem parameter setting:

  • 0105 (Db2 performance trace)
  • 0106 (system parameters)
  • 0199 (data set statistics)
  • 0365 (remote location statistics)
  • 0402 (monitor profile warnings or exceptions)

Sharon Roeder is a Software Developer for Db2 for z/OS Development, and Paul McWilliams is an Information Developer for Db2 for z/OS.

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