RE: How Memory Pools work

["Andy Nolen-Parkhouse" <aparkhouse@xxxxxxxxxxx>]

Adam,

You've received good replies so far.  I'll add my perspective.  At 256 MB
you really do not have much memory on your system.  On a small system with a
varying workload, your best bet may be to ensure that all of your pools are
shared and turn on the performance adjustment system value (QPFRADJ) to
continually adjust your memory allocation.  Thus regardless of the initial
values at IPL, memory will move from one pool to the other as needed.

If you have this little batch job and it gets called every few minutes
during working hours to rate a policy, you may want to give it its own
non-shared memory.  If it is very important that this work be done in a
timely manner, then this could become more urgent.  If you have an employee
on the telephone with a customer and they're stalling for three minutes
while waiting for a response from the computer, then make sure that the
program is loaded in its own pool and doesn't get swapped out.

Your vendor's description sounds valid.  If you are using shared memory
pools with performance adjustment and you have this batch job which wakes up
infrequently, then the batch job will get swapped to disk and the memory
will be allocated to interactive, spooling or system work.  That's the way
the system works, particularly on a machine as small as yours.

So you need to decide how important it is that this batch job remains in
memory.  If you hard-allocate memory for this task, then you are taking it
away from something else.  I would suggest that you look through some of the
faulting and paging topics in the Work Management section of the InfoCenter.
Then watch your system for a day and see if your entire system is short on
memory.  Once you know what to look for, a few minutes every hour with the
WRKSYSSTS display for a day should let you know whether you should buy
addition memory or try to reallocate what you already have.  If everything
is shared and all pools have bad paging/faulting levels, then removing
memory from the shared pools will make the entire system worse, (except for
that one batch job).

Regards,
Andy Nolen-Parkhouse

> Can someone explain how memory pools work?  Our system currently has 256
> MB
> total and apparently our interactive is around 150-160.  We also have a
> machine, base and spool pool.