Enabling PMI data collection

When PMI service is enabled, the monitoring of individual components can be enabled or disabled dynamically. PMI provides four predefined statistic sets that can be used to enable a set of statistics. The following table provides details about the statistic sets. If the predefined statistic sets do not meet your monitoring requirement, the Custom option can be used to selectively enable or disable individual statistics.

Table 1. Statistic set . Enable PMI by using the administrative console, wsadmin tool, or Java™ Virtual Machine Tool Interface (JVMTI).

Statistic set	Description
None	All statistics are disabled.
Basic	Statistics that are specified in J2EE 1.4, and popular statistics like CPU usage and live HTTP sessions are enabled. This set is enabled out-of-the-box and provides basic performance data about runtime and application components.
Extended	Basic set plus key statistics from various WebSphere® Application Server components like WLM, and dynamic caching are enabled. This set provides detailed performance data about various runtime and application components.
All	All statistics are enabled.
Custom	Enable or disable statistics selectively.

Custom setting

WebSphere Application Server Version 6.0 introduces fine-grained control to enable/disable statistics individually. The fine-grained control is available under the custom statistic set.

Sequential Update

To minimize the monitoring overhead, the updates to CountStatistic, AverageStatistic, and TimeStatistic are not synchronized. Since these statistic types track total and average, the extra accuracy is not worth the performance cost. The RangeStatistic and BoundedRangeStatistic are sensitive; therefore, they are always synchronized. If needed, updates to all the statistic types can be synchronized by checking the Use sequential update check box.