vSphere hot add

VMware vSphere hot add is a feature that allows an administrator to increase the random access memory (RAM) capacity of a running virtual machine (VM) without downtime.

VSphere hot add can be enabled during the configuration of VMware VMs running hardware version 7 and newer, on compatible OSes and with the use of VMware Tools. Because vSphere hot add is disabled by default, and VMs must be powered off to enable it, administrators should consider enabling hot add from the start if there's a possibility that a VM will need more resources at any point.