Re: Memory Pool questions

Yeah, acceptable faulting/paging rates is like "in the eye of the
beholder".

If you have little to no 5250 activity they IDK why one would switch
system value QCTLSBSD from QBASE to QCTL. That just seems to be a knee
jerk reaction on new systems back from when 5250 and heavy ERP batch type
jobs were the norm. On my Domino lpars activities in those are barely
noticeable. I remember discussing this with Al Barsa. It was kind of
tough for him to get his head around these "non traditional" loads on IBM
i.

Back before automatic adjustments, and on machines where interactive was
heavy during the day and batch was heavy during the night we used to
adjust those with job schedule entries. Creatively called NIGHT and DAY.

There is a school of thought that one may want to forego automatic
adjustments because constant slight adjustments make your query optimizer
reoptimize. "Oh, now that you have this size memory pool..." kind of
stuff.
The opposite school of thought is that IBM's automatic adjustments aren't
timely enough and you need to purchase a third party product which is more
mobile. Let me explain. In order to not be too drastic IBM's adjustments
only do a little bit at a time. If you start up the batch job from heck
at night then it make take numerous automatic slight adjustments to get
more memory from interactive to batch. These third party tools are more
agile and don't share IBM's concerns. They'll move bigger chunks of
memory at a time.

I still use IBM supplied automatic adjustments. And not just at IPL time.
Not saying that's a "best practice". Just what we do.

Without automatic adjustment one must remember to adjust for:
- Hardware upgrades
- memory shifting between lpars
- Huge processing differences like the NIGHT and DAY example above.

One must also be diligent in monitoring this.

Another reason NOT to automatically adjust may be a critical operation
which may fire off at any time. Perhaps you set up a special job, with
it's own subsystem and memory pool, that may sit idle most of the time but
when it's needed you want high priority and peak performance. Hospital
admissions comes to mind.



Rob Berendt