PSA behavior after collection shutdown.

Products

• Subsystem Analyzer for DB2 for z/OS
• Database Management for DB2 for z/OS - Performance Suite
• Database Management for DB2 for z/OS - SQL Performance Suite
• Detector for DB2 for z/OS

Issue/Introduction

Does Subsystem Analyzer collection completely shut down all activities and processes related to SSA after a STOP(SSA) is issued and there is no dormant activity remaining and consuming CPU/ZIIP? Could you provide some detailed information about how this can be verified?

 

Environment

Release : 19.0

Component : CA Subsystem Analyzer for Db2 for z/OS

Resolution

The primary Subsystem Analyzer module PSACIDC1 or PSACIDC2 will stay in the ECSA after the shutdown of Subsystem Analyzer, and will stay there awaiting reactivation.  This is done to ensure that no in-flight abends occur when Subsystem Analyzer is shutting down. So, yes some piece of Subsystem Analyzer is in the system, but it is not active or intrusive. The best way to confirm it is for us to look at a console dump of XMANAGER and the DBM1 of the DB2 subsystem in question. We can verify the dump here, but we can also build an Instruction Fetch SLIP, with ACTION=TRACE (or DUMP) on the instructions in the PSACIDCx module to ensure that it is not called, or any instructions executed. Here is the SLIPCOMM dump of XMANAGER and DBM1 address space, and be sure to include ECSA -SDATA=(PSA,SQA,LSQA,RGN,TRT,CSA,SWA,SUM,GRSQ)