How ESXi and the EM4J Agent Improve Memory Utilization

ESXi supplies virtual machines with virtual memory and ensures that the virtual memory is backed with physical memory when the virtual machine requires it.

ESXi ensures the efficient use of physical memory by employing shared memory pages, ballooning, memory compression and, as a last resort, disk swapping. These techniques allow ESXi to reduce the amount of physical memory consumed by the virtual machines. Disk swapping, where memory pages are written to and from disk, is least efficient because disk I/O is much slower than memory I/O. With Java, disk swapping is disruptive because when garbage collection occurs, page swapping activity can spike, causing performance degradations and failures.