By default, caching is not enabled for multi-file disk stores. If you want to store events from a multi-file store in the cache, set the EnableStoreCaching and EnableCaching realm configuration properties to true and restart the Universal Messaging server instance.

When creating a channel with a multi-file store, set the Cache on Reload and Enable Caching channel storage properties to true. For details about the server configuration properties, see the section "Realm Configuration" in the Administration Guide. For details about the channel storage properties, see Storage Properties of Channels and Queues.

All multi-file disk stores use a default cache of size 10 000 events.

To cater for the publish/subscribe rates, available heap size, and individual event sizes in your environment, the cache size can be changed with the system property CACHE_SIZE, as described in the section Server Parameters.

For example, when your publishers are fast and subscribers are slow, the event size is small and you have more than 10 000 events awaiting delivery, then subscribers might not be accessing cached events and are instead loading the events from disk. In this case you can increase the cache size in order to achieve a possible performance gain.