Make sure you have an adequate amount of physical memory on each machine in your deployment. Additional physical memory improves performance and enables the Instant Messaging server to operate at peak volume. With sufficient memory, Instant Messaging can operate efficiently without excessive swapping.
For most deployments, you need at least 256 MB of RAM. The amount of RAM needed depends on the number of concurrent client connections, and whether the server and multiplexor are deployed on the same host. For information about concurrent connections, see Creating Your Instant Messaging Usage Profile. For information on hosting the server and multiplexor on the same host, see Developing Instant Messaging Architectural Strategies.
You can set the amount of memory allocated to the server by modifying the iim.jvm.maxmemorysize parameter in the iim.conf file. This parameter specifies the maximum number of megabytes of memory that the Java Virtual Machine (JVM) running the server is allowed to use. The default setting is 256 MB, and the maximum setting is 500 MB. For instructions on modifying this parameter, see the Sun Java System Instant Messaging 7.2 Administration Guide.