IBM Tivoli Monitoring > Version 6.3 Fix Pack 2 > Installation Guides > Installation Guide > Performance tuning > Tivoli Data Warehouse > Summarization and Pruning Agent
IBM Tivoli Monitoring, Version 6.3 Fix Pack 2
Set the maximum Java heap size
The Summarization and Pruning Agent runs in a Java virtual machine (JVM), which uses the JDBC (Java Database Connectivity) interface to communicate with the warehouse database. If the maximum Java heap size of the JVM is set to a low value, performance can be degraded by frequent garbage collections.
The maximum Java heap size is controlled by the -Xmx option. By default, this option is not specified in the Summarization and Pruning Agent configuration file. If this option is not specified, the default value used by Java applies as follows:
- Half the available memory with a minimum of 16 MB and a maximum of 512 MB.
- Half the available memory with a minimum of 16 MB and a maximum of 512 MB.
- Half the real memory with a minimum of 16 MB and a maximum of 2 GB.
The above values are from the IBM Developer Kit and Runtime Environment, Java Technology Edition, Version 6 Diagnostics Guide.
To set the size of maximum Java heap size for the Summarization and Pruning Agent, edit the configuration file (KSYENV on Windows, sy.ini on UNIX or Linux) and modify the KSZ_JAVA_ARGS variable as shown below:
KSZ_JAVA_ARGS=-Xmx512m
- A maximum Java heap size of 512 megabytes (shown in the example above) is adequate for most environments.
- In addition to the “mx” Java parameter, you can also specify the -verbose:gc Java runtime parameter, which causes diagnostic messages related to garbage collection to be written to the log. If there are an excessive number of garbage collection entries consider increasing the size of the Java heap.
- For more information about Java heap tuning parameters, see the IBM Developer Kit and Runtime Environment, Java Technology Edition, Version 6 Diagnostics Guide, which is available from http://www.ibm.com/developerworks/java/jdk/diagnosis.
Parent topic:
Summarization and Pruning Agent