Memory and paging

Ensure that paging levels are minimal. The JVM manages its heap by assuming that the entire heap is in memory. If significant portions of the heap are on swap devices, the node might go into a "thrashing" situation and spend the most time shuffling pages between real memory and swap.

Note: The JVM performs very badly, even in low transaction volume environments if the OS has to continually page the JVM heap to disk.

The "thrashing" situation could arise for many reasons including:

Starting a JVM with a heap size that is larger than physical memory
Starting too many JVMs and other workloads such that the combined working set size is larger than the physical memory