Data set I/O collection tuning

Limitation:

High CPU utilization in the OMEGAMON® Subsystem address space, specifically with the KDFSCOL and KDFSMIG modules.

Workaround:

Data set I/O collection refers to the feature of OMEGAMON for Storage on z/OS® which allows customers to get millisecond response time information at the data set level. Use one or both of the following methods to manage this feature:

• Turn the feature on or off at the volume level. In general, monitor only volumes for which data set response time is a critical issue or volumes that are known to have problems.
• Regulate the feature by using parameters that specify when data set level I/O monitoring starts for a volume. Apply these parameters whenever you need to monitor a large number of volumes.

Use one of the following methods to collect data set level I/O statistics for a device:

• Monitor I/O events based on a fixed interval, called sample count. Sample count specifies how often I/O events are monitored. If the sample count for a device is set to 1 (the default), every I/O event is monitored. If the sample count is set to 5, every fifth I/O is monitored. Valid values are 1 through 99.

• Activate device monitoring when there is an extended period of response-time degradation, and deactivate monitoring during periods of acceptable response time. You specify a millisecond response (MSR) trigger value for a device and a global trip count that controls the number of times an MSR exception occurs before monitoring resumes for the device. Valid values are 1 through 999.

  Use PARMGEN to set these parameters.