Cache replication | Offload to disk
In-memory cache
A newly generated cache entry is stored in memory (JVM) until it fills up. The maximum number of cache entries that can be stored in the JVM is controlled by the Cache size parameter, configurable in the administrative console. The default is 2000.
It is extremely important to monitor the heap consumed by the cache using verbose GC tracing or heap dump analysis.
This helps in determining the size of the in-memory cache. Using the GC logs during performance testing, one should arrive at the appropriate size of the in-memory cache.
The in-memory cache size is limited by the size of the JVM. As a rule of thumb, IBM recommends leaving 40% of JVM free with caching to avoid excessive fragmentation and out-of-memory problems causing crashes. Gradually increase the cache size and fine-tune the JVM to reduce fragmentation.
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