Re: AS/400 Performance

In addition to what has been said already by others:
If you do not find any obvious bottlenecks (CPU, paging, disk I/O), next thing
to look at are comm IOPs/lines usage (if you have significant number of users
attached in this way), and lock considerations (jobs may lock each other from
access to some resource - system is underused, but response time is high).
Both will require using Performance Monitor (part of base system - to collect
the data) and Performance Tools reports (separate product - to analyze the
data).
In principle, you can analyze data without PT - by querying PM files. File
structures are described in Work Management Guide and PT documentation, but
maybe for beginner it can be difficult.
PM collection overhead should not be higher than 3-5% CPU (it is mostly CPU, so
if your problem is not in CPU area, then it will have no effect whatsoever).
PM can create a bigger overhead, but only on real big systems - many thousands
of jobs.

There are more tools for RISC versions, but since you are v3r2, they do not
apply.

If your problem is with CPU or memory, use Performance Adjuster - it does a good
job.

RCLSTG will not do a defrag - it has another purpose. There is a DEFRAG tool
(PTF) for CISC - it will defragment free areas on DASD, but it is needed only in
very special cases.
In general, due to the way AS/400 allocates disk space, fragmentation should not
be a problem in general,
If some key files are fragmented, it can be a performance bottleneck - they can
be "defragged" by saving and restoring them.

There is no disk balancing tool for CISC versions - only for RISC.

Best regards
    Alexey Pytel



Gary Munroe <GMUNROE@flemingc.on.ca> on 05/06/99 10:17:16 AM

Please respond to MIDRANGE-L@midrange.com

To:   midrange-l@midrange.com
cc:    (bcc: Alexei Pytel/Rochester/IBM)
Subject:  AS/400 Performance





What is the best way to find out how the system is performing (v3r2)?
We seem to be noticing slowdowns but cannot necessarily narrow down
the cause.  We look at WRKACTJOB to see who might be running an
intensive job but it doesn't always reflect the slowdown we feel.  I
know there is performance data collection but we are under the
impression it makes a big impact on the system by itself.  Are there
any general maintenance tips we should be following?  Also, does a
reclaim storage do a defrag to the disks?  What would?  Would this
help?

Thanks.


 __________________________________________________________________
| Gary Munroe                                                      |
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