RE: System tuning recommendations

Mike,

Your mileage will vary, depending on your application mix.  Generally
you would calculate a base level for your machine and *BASE pools, then
allocate your remaining memory to provide acceptable interactive
response time and then provide the remainder to your base and spooling
pools.  Your machine pool is vital and the manual referenced below
provides formulas for calculating a starting point.  If you have not had
the opportunity to read much in the Work Management manual, I would
suggest looking at the section with the heading 'Setting Performance
Values Manually'.  This provides some of the guidelines for setting
initial values and then adjusting them based upon paging and faulting
levels.  Tuning is somewhat of an iterative process - you give it your
best shot, then adjust the values based upon the results you obtain

You can do some of this using the values given by the automatic
performance tuning.  When your system reaches what you consider to be
its peak interactive load, turn off performance adjustment and check
your paging and faulting levels.  Below are the maximum acceptable
levels used by performance adjustment (from the manual above):

Pool            Minimum Faults  Maximum Faults
*MACHINE        10.00           10.00
*BASE   10.00           100
Interactive 5.00                        200
Spool   5.00                    100
Batch   10.00                   100

With your configuration, your batch jobs should be running in *BASE but
the same faulting levels apply.  Gradually lower your interactive pool
size until your paging/faulting levels exceed your maximum acceptable
level, then make the pool slightly larger.  That would be an appropriate
pool size for your workload.  You also need to deal with your activity
levels and should be familiar with how adjusting the activity level of a
pool affects performance.  After dealing with pool size and activity
levels, then determine whether you should set your pool paging to *FIXED
or *CALC.

The above is grossly oversimplified but could provide a starting point.
You can feel free to play with pool sizing and activity levels because
you can easily return to your status quo by setting you QPFRADJ value
back to '3'.

I would ask again whether your system is performing poorly.  If it is
working well under system adjustments, then you have more flexibility
than if you manually set your values.  The system will give highest
priority to your interactive work and the operating system, but will
make memory available for batch work if it is not required by those
tasks.

Regards,

Andy Nolen-Parkhouse
IBM Certified Expert, iSeries Technology



> On Behalf Of Condon, Mike
> Sent: Saturday, October 20, 2001 1:16 PM
>
> What pool sizing is recommended for mostly green screen apps,
occasional
> batch?
>
> -----Original Message-----
> From: Andy Nolen-Parkhouse [mailto:aparkhouse@mediaone.net]
> Sent: Saturday, October 20, 2001 8:44 AM
>
> Mike,
>
> I generally measure system performance by user complaints, not by
> response times.  If your users are content with the performance of
your
> system, then why change anything?
>
> From the looks of your system status displays, you really do not have
> any pool allocations because all of your pools are managed by the
> system.  If you have some grizzled veterans among your counterparts in
> the other divisions, they may feel that the performance adjustments
> could never perform the level of tuning that they can obtain manually.
> This has a historical base in the earlier releases of OS/400, which
> really did not do an exemplary job of managing resources.  It may also
> have a base in arrogance and professional pride.
>
> As a grizzled veteran myself, I've found that for a fairly generic
> system, performance under system control provides more than adequate
> allocation of resources and responds to changing requirements promptly
> enough.  It is 'good enough'.  If you start to require special batch
> subsystems or something different, you may find some manual tuning
> beneficial.
>
> What would your counterparts propose?
> Are your users content?
>
> Andy
>
> Andy Nolen-Parkhouse
> IBM Certified Expert, iSeries Technology
>
> > On Behalf Of Condon, Mike
> > Sent: Friday, October 19, 2001 4:49 PM
> >
> > Some of our counterparts in other divisions managing AS400's have
> > commented
> > negatively
> > on our pool size allocation, and also against using IBM's QPRFADJ
set
> to 3
> > (they prefer 0).
> > Our system is primarily green screen rpg/db2 stuff, fairly
> > straightforward.
> > We have about
> > 200 open interactive sessions on a typical day. Our interactive CPW
is
> 70.
> >
> > My question is - do any of you all have any recommendations for
system
> > tuning given our application?
> >
> > Here is a snapshot of our wrksyssts:
> >
> >                             Work with System Status
> > S105DGAM
> >
10/19/01
> > 15:29:26
> >  % CPU used . . . . . . . :        7.0    Auxiliary storage:
> >
> >  % DB capability  . . . . :        3.0      System ASP . . . . . . :
> > 77.30 G
> >  Elapsed time . . . . . . :   00:00:40      % system ASP used  . . :
> > 29.5261
> >  Jobs in system . . . . . :       2233      Total  . . . . . . . . :
> > 77.30 G
> >  % perm addresses . . . . :       .007      Current unprotect used :
> > 2589 M
> >  % temp addresses . . . . :       .053      Maximum unprotect  . . :
> > 54509 M
> >
> >
> >  Type changes (if allowed), press Enter.
> >
> >
> >
> >  System    Pool    Reserved    Max   -----DB-----  ---Non-DB---
> >
> >   Pool   Size (M)  Size (M)  Active  Fault  Pages  Fault  Pages
> >
> >     1      111.03     67.31   +++++     .0     .0   15.3   25.2
> >
> >     2      201.78       .26      43     .0     .0    3.7   13.9
> >
> >     3       10.23       .00       8     .0     .0    4.0    8.0
> >
> >     4      700.93       .00      36    1.5    6.0   10.8   25.0