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Performance Management Guide

Reporting a Performance Problem

You should report operating system performance problems to IBM support. Use your normal software problem-reporting channel. If you are not familiar with the correct problem-reporting channel for your organization, check with your IBM representative.

What is a Performance Problem?

Support personnel need to determine when a reported problem is a functional problem or a performance problem. When an application, a hardware system, or a network is not behaving correctly, this is referred to as a functional problem. For example, an application or a system with a memory leak has a functional problem.

Sometimes functional problems lead to performance problems; for example, when the functions are being achieved, but the speed of the functions are slow. In these cases, rather than tune the system, it is more important to determine the root cause of the problem and fix it. Another example would be when communication is slowed because of networks or name servers that are down.

Performance Problem Description

Support personnel often receive problem reports stating that someone has a performance problem on the system and providing some data analysis. This information is insufficient to accurately determine the nature of a performance problem. The data might indicate 100 percent CPU utilization and a high run queue, but that may have nothing to do with the cause of the performance problem.

For example, a system might have users logged in from remote terminals over a network that goes over several routers. The users report that the system is slow. Data might indicate that the CPU is very heavily utilized. But the real problem could be that the characters get displayed after long delays on their terminals due to packets getting lost on the network (which could be caused by failing routers or overloaded networks). This situation might have nothing to do with the CPU utilization on the machine. If on the other hand, the complaint was that a batch job on the system was taking a long time to run, then CPU utilization or I/O bandwidth might be related.

Always obtain as much detail as possible before you attempt to collect or analyze data, by asking the following questions regarding the performance problem:

Reporting the Problem

When someone reports a performance problem, it is not enough just to gather data and then analyze it. Without knowing the nature of the performance problem, you might waste a lot of time analyzing data which may have nothing to do with the problem being reported.

Before you involve support personnel to report a problem, prepare in advance the information that you will be asked to supply to facilitate the problem to be investigated. Your local support personnel will attempt to quickly solve your performance problem directly with you.

Three further ways you can help to get the problem resolved faster are:

  1. Provide a clear written statement of a simple specific instance of problem, but be sure to separate the symptoms and facts from the theories, ideas and your own conclusions. PMRs that report "the system is slow" require extensive investigation to determine what you mean by slow, how it is measured, and what is acceptable performance.
  2. Provide information about everything that has changed on the system in the weeks before the problem. Missing something that changed can block a possible investigation path and will only delay finding a resolution. If all the facts are available, the performance team can quickly eliminate the unrelated ones.
  3. Use the correct machine to supply information. In very large sites it is easy to accidentally collect the data on the wrong machine. This makes it very hard to investigate the problem.

When you report the problem, supply the following basic information:

If this is the first report of the problem, you will receive a PMR number for use in identifying any additional data you supply and for future reference.

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