[IQUG] Slower and slower performances at IQ version 16.0 while many more concurrent jobs were run in parallel

Steve Shen sshen at sscinc.com
Fri Sep 7 09:23:09 MST 2018


Today topic:
                Changing from fast to slower and slower IQ 16.0 performance at Linux Red Hat 7.4 using file systems

Let me share my IQ environments with you:


1.       The O/S is Red Hat version 7.4.

2.       he IQ version is "SAP IQ/16.0.110.2805/11355/P/sp11.20/Enterprise Linux64 - x86_64 - 2.6.18-194.el5/64bit/2018-06-15 02:57:16".

3.       The senior manager overrode my concerns on its potential performance penalty and decided using file systems because SAP manuals documented that file systems were supported at IQ.

4.       The file systems used SSDs.

My clients were complaining about the following:

1.       The average reporting job duration on the similar SQL statements was 395 seconds while 5 concurrent jobs were run in parallel.

2.       It became 475 seconds while 11 concurrent jobs were run in parallel.

3.       It became 666 seconds while 20 concurrent jobs were run in parallel.

4.       Many more concurrent parallel runs will take place in the next two weeks!

In other words this IQ performance ran very fast when there were few jobs running concurrently; but the performance was declining heavily while many more concurrent jobs were run in parallel!

My key clients could not accept this kind of declining performance at IQ version 16.0.

I have turned off both OS_File_Cache_Buffering and OS_File_Cache_Buffering_Tempdb.  I also set IQ_USE_DIRECTIO=1 even though it's not necessary at Red Hat 7.4.

What else can I do to make the first IQ instance at Linux using file systems to perform much better in many concurrent parallel runs?

Thank you.

Regards,

Steve Shen


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