Tim
At 12:12 AM 2/18/98 -0500, you wrote:
>Hello all,
>I have been handed the chore of performance tuning an IBM F50 (192MG
>mem) AS400 at release V3R2. Any suggestions as to what would be a good
>route for me to follow? I previously changed the system value QPFRADJ
>to be '2' which means the AS400 can optimize its pools at IPL and at
>radic intervals throughout the day, yet there are some major system bog
>downs still occurring.
As Dean said, we're into religious arguments here. So I'll jump in where angels fear to tread, anyway.
Concerning my credentials here, I used to be the primary technical support person for Help/Systems' product, AutoTune. This product and PAE's Charlie Tuner both preceded IBM's built-in dynamic tuner (QPFRADJ) by many years. For the longest time, IBM refused to acknowledge the need for a tuning monitor, and when they _did_ implement one, they did a pretty horrible job, IMO.
BTW, I no longer work at Help/Systems, so these opinions are mine own, my very own. <bg>
EMC (I think) used to have a pretty good guide to tuning. Their site is <http://www.emc.com>, but I didn't see much there. Maybe an e-mail to them. My (old) copy is buried deep in moving boxes.
Both NEWS/400 & Midrange Computing have had good articles on tuning over the years. Check their sites or get their reference CD-ROMs.
Help/Systems has a site at <http://www.helpsystems.com>. They have a good little intro to tuning, and the AutoTune manual is available for review. Obviously, they're out to sell the product.
I assume Charlie (PAE) has a site, too. (Peter O'Connor, do you want to jump in here?)
Dean A. has often said he doesn't like dynamic tuners, doesn't think they are responsive enough. I hope he's referring to QPFRADJ that's a part of the system, because it monitors at 15 minute intervals, and the system is far too dynamic for that to do much good, IMO. I know that AutoTune (and Charlie, too, I believe) can be set to monitor and adjust performance parameters every 5 _seconds_, without material degradation to overall performance (a few seconds of total cpu time every hour). That's 180 times finer granularity than the native function. A typical installation may monitor at 10 second intervals. IMO, Dean's comments do not apply to the third-party dynamic tuners, which are completely different animals from the built-in tuning function.
BTW, we use AutoTune on all 12 of our AS/400's, from B35 to F80 to 200 to 510 to 620. We would not even consider not using it.
Having said all that, here're some suggestions, based loosely on AutoTune's suggested values.
1. As others have said, change QCTLSBSD = QCTL.
2. IPL once with QPFRADJ = 1 to let the machine set QMCHPOOL. Then turn it off.
3. Set QBASPOOL = 8% of total CPU if there's no batch work in *BASE, 14% if there is. Set QBASACTLVL = 5 for starters.
4. Set QSPL size = (80 x # non-AFP printers) + (200 x # AFP printers), with a max of 2300K. Set activity level to number of printers, max of 5.
5. Set QBATCH size = 1000 x # of jobs; same for other separate batch pools. Activity level should be same as number of jobs that can run at once.
6. *INTERACT (and other interactive) size = 250 x # of non-OfficeVision jobs + 600 x # of OfficeVision jobs. (IMO, this'll be on the low side.) Activity level should be c. 1/10 of maximum possible jobs in subsystem
7. Set QCMN = min(120 x # of jobs and 20% of total CPU). Activity level should be c. 1/10 of workstations in pool
This is the basics. Once you've done this, watch things for awhile. Make adjustments and see what happens. BTW, adjustments to QMCHPOOL should be fairly moderate. There's usually a cutoff point beyond which there is no additional advantage.
Activity levels also have a steep cutoff. Adjust by 1 at a time, give things time to settle down, and look at the results.
I heartily recommend a product like AutoTune or Charlie (you know my bias <g>--sorry, Peter). Both are available, I believe, in 30-day trials.
Let me address the position that dynamic tuners are too late with the following thought:
Q: Which is better, a watch that doesn't run, or one that is 2 minutes off?
A: The one that doesn't run, because it's right twice a day. The other one is wrong all the time.
Cheers
Vernon Hamberg
Systems Software Programmer
Old Republic National Title Insurance Company
400 Second Avenue South
Minneapolis, MN 55401
(612) 371-1111 x480
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