vSphere High Performance Cookbook

Monitoring host-swapping activity

Excessive memory demand can cause severe performance problems for one or more virtual machines on an ESXi host. When ESXi is actively swapping from the memory of a virtual machine to disk, the performance of that virtual machine will degrade. The overhead of swapping a virtual machine's memory to disk can also degrade the performance of other virtual machines, because the virtual machine expects to be writing to RAM (speeds measured in nanoseconds) but it is unknowingly writing to disk (speeds measured in milliseconds).

The metrics in the vSphere Client for monitoring swapping activity are the following:

• Memory Swap In rate: The rate at which memory is being swapped in from disk.
• Memory Swap Out rate: The rate at ...