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The basic reason for multiple pools is to reduce the competition between different types of workloads, especially long running batch workloads, short high CPU interactive transactions, and the system jobs running in the *Base pool. QPFRADJ takes time to adjust because it only moves a small amout of memory at a time to avoid overcompensating.( I'm pretty sure that it's every 30 seconds, someone correct me if I'm wrong) On the other hand, it always overcompensates after moving from a day type workload to a night type workload, i.e. 95% interactive to 95% batch; it will move as much memory as it can to the active pool and this can cause some applications to experience long startup times as QPFRADJ takes it's time moving the memory back where it is needed. You can mitigate this somewhat by setting minimum/maximum sizes using WRKSHRPOOL and F11 to adjust the tuning data. In your case, if you set the minimum size of pools 3 and 5 to 20% they would not drop below about 3000(M), though they would still be able to swap the additional memory between the pools as needed. You can find more info about this in Software Knowledgebase document #4621424, Separating Batch Work from *BASE at http://www-912.ibm.com/s_dir/slkbase.nsf/slkbase Regards, Scott Ingvaldson AS/400 System Administrator GuideOne Insurance Group -----Original Message----- Date: Mon, 27 Jan 2003 09:10:24 -0500 From: rob@dekko.com Subject: Why not *SHRPOOL1? On our 840 12-way we have system value QPFRADJ set to "2=Adjustment at IPL and automatic adjustment". And we have the following pools: System Pool Reserved Max Pool Size (M) Size (M) Active Pool 1 2618.98 655.60 +++++ *MACHINE 2 6307.05 55.12 530 *BASE 3 3935.35 <.01 80 *SHRPOOL1 4 303.44 .00 20 *SPOOL 5 1835.15 .20 227 *INTERACT Actually, this does a pretty good job. However, if you start this big whopping job in one subsystem, or the other, then it takes awhile until QPFRADJ switches memory over. In the Rochester lab (just last week) we had a Query take 3 minutes until we switched QINTER to run in *SHRPOOL1. They were still scratching their heads to figure out how often QPFRADJ adjusts. After the switch it took only a very few seconds. So now my boss asked me a good question. Why don't we just use two pools: *MACHINE and *SHRPOOL1? And avoid that time lag of QPFRADJ. Questions and comments appreciated. Rob Berendt
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