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Thursday, August 07, 2014

Poor Performance Followup

As a follow-up to the previous poor performance post I thought I'd post what the outcome was. As it turns out we checked performance tuning settings in TSM and AIX and no performance increase was seen. We asked the DB2 admins to review any of their settings and they could not find any tunables that had not already been implemented. We sent in servermon.pl output and although they saw performance that was sub-par, they couldn't designate what was causing it. There are no server/adapter/switch/disk/tape errors so nothing emerged as the culprit for our poor throughput performance.

So we reviewed the backup time of each TSM storage agent server used to backup this 101 TB SAP database. At the time the storage agents that perform the backup consisted of 5 LPARS, 4 of those in a single frame each with their own assigned I/O drawer. The 5th was in a separate 740 frame with its own I/O drawer. The 5th storage agent was completing the backup in a fraction of the time of the other 4 so we concluded we must be overloading the CEC on the 740. We moved one of the four storage agents out of the frame to a secondary frame and the results were awesome. See below:

You'll notice that the backup time didn't change with the update of the tape drives from E06 to E07. Hardware layout matters more than the performance of the tape drives. When a vendor tells you just updating the hardware to newer iterations will increase performance take it will a grain of salt. In our case we did testing of the new tape drives and no performance gains were seen but the go ahead was given to upgrade to the newer hardware and as you'll see we didn't gain anything until we reworked the environment. Our task now is to identify how to increase TSM internal job performance (i.e. migration and storage pool backup) which has not seen significant performance gains from the tape upgrades.

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