IBM Tivoli OMEGAMON XE V3.1 Deep Dive on z/OS

Chapter 5. IBM Tivoli OMEGAMON XE performance optimization 167

5.4.4 Situation threshold and interval

IBM Tivoli supplies a set of default thresholds with each IBM Tivoli OMEGAMON

XE solutions. However, the defaults may not be appropriate for your installation.

Adjust the thresholds for each exception to fit the performance standards at your

installation. For example, situations that are part of a

health check process can

use a longer interval such as 30 minutes, whereas situations that detect a

resource shortage condition probably need a more frequent interval.

Some IBM Tivoli OMEGAMON XE products have specific critical threshold

situations for stall and crash prevention that automatically start by default, but this

may not be true for their warning situations. At many sites the warning yellow

lights are ignored, so it would be a waste of processing to distribute and start

these situations. Other sites pay close attention to warning alerts, in which case

the situations should be autostarted. With IBM Tivoli OMEGAMON XE you can

set different intervals for every threshold. Be aware that picking different intervals

will cause higher overhead. Some products, such as IBM Tivoli OMEGAMON XE

for CICS on z/OS, have preselected critical threshold situations for stall and

crash prevention automatically started as a default. However, they do not

autostart any warning situations.

The predefined situations may have more frequent sampling than required by

your environment. Recognize that not all data is equally important, nor is it

equally expensive to collect. Some higher processing exceptions may not be

crucial to availability in your environment. Ideally, you would like to realize huge

benefits at low cost, but this is not always possible. Avoid high processing

requirements and low benefits. The answers may be different for various

applications running under the same subsystem.

IBM Tivoli OMEGAMON XE attempts to have low overhead defaults. However, no

vendor can know your environment or what is relevant to your business

applications. IBM Tivoli OMEGAMON XE was designed to provide in-depth

analysis, as you will need these capabilities to deal with problems when they

have been identified. However, awareness of situations is not necessarily

minimized by selectively disabling data collection. It is best to disable the items

that you can categorize as low benefit with high overhead.

For migration purposes, IBM Tivoli OMEGAMON XE for x on z/OS uses the

same default thresholds as the associated OMEGAMON II component. However,

you can take advantage of new capabilities to selectively disable Warning

thresholds. Follow the instructions in the configuration and customization guide

for your IBM Tivoli OMEGAMON XE product to run KXEMIGR, a utility that

migrates OMEGAMON II critical and, optionally, warning thresholds to be used

as predefined situations in IBM Tivoli OMEGAMON XE.