In this scenario, you have just upgraded or migrated your system
and it now appears to be running slower than before. This scenario will help
you identify and fix your performance problem.
Situation
You
recently upgraded your iSeries™ server
to the newest release. After completing the upgrade and resuming normal operations,
your system performance has decreased significantly. You would like to identify
the cause of the performance problem and restore your system to normal performance
levels.
Details
Several
problems may result in decreased performance after upgrading the operating
system. You can use the performance management tools included in i5/OS™ and Performance Tools licensed
program (5722-PT1) to get more information about the performance problem and
to narrow down suspected problems to a likely cause.
- Check CPU utilization. Occasionally, a job will be unable to access some
of its required resources after an upgrade. This may result in a single job
consuming an unacceptable amount of the CPU resources.
- Use WRKSYSACT, WRKSYSSTS, WRKACTJOB, or iSeries Navigator system
monitors to find the total CPU utilization.
- If CPU utilization is high, for example, greater than 90%, check the amount
of CPU utilized by active jobs. If a single job is consuming more than 30%
of the CPU resources, it may be missing file calls or objects. You can then
refer to the vendor, for vendor-supplied programs, or the job's owner or programmer
for additional support.
- Start a performance trace with the STRPFRTRC command, and then use the
system and component reports to identify and correct the following possible
problems:
- If the page fault rate for the machine pool is higher than 10 faults/second,
give the machine pool more memory until the fault rate falls below this level.
- If the disk utilization is greater than 40%, look at the waiting and service
time. If these values are acceptable, you may need to reduce workload to manage
priorities.
- If the IOP utilization is greater than 60%, add an additional IOP and
assign some disk resource to it.
- If the page faults in the user pool are unacceptably high, refer to the
topic Automatically tune performance.
- Run the job summary report and refer to the Seize lock conflict
report. If the number of seize or lock conflicts is high, ensure
that the access path size is set to 1TB. If the seize or lock conflicts are
on a user profile, and if the referenced user profile owns many objects, reduce
the number of objects owned by that profile.
- Run iDoctor with the Task switch option for five
minutes. Then analyze the resulting trace data with the task switch monitor.
Identify and resolve any of the following:
- Jobs waiting for CPU
- Jobs faulting
- Seize conflicts