Virtual Memory Swapping
Wormly Metrics provides VM monitoring - among thousands of other metrics.
When the processes running on server / instance attempt to allocate more memory than your system has available, the kernel begins to swap memory pages to and from the disk.
This is done in order to free up sufficient physical memory to meet the RAM allocation requirements of the requestor.
Wormly monitors the number of pages being swapped to and from the disk over time. It presents this information with the following trend graph:
Virtual Memory swapping is an “expensive” activity in terms of its impact on overall system performance. If processes on your system regularly attempt to allocate more than the available physical RAM, you may experience drastic increases in web site response times and loss of execution speed.
Unfortunately only two solutions exist - either optimize your applications to utilize memory more efficiently, or add more physical RAM to the system.