You can use virtual flash resource on an ESXi host to configure a swap cache. The host swap cache is allocated from a portion of the virtual flash resource.
You can virtualize flash devices on a host to use as a virtual flash resource on that host, regardless of the type of flash device. Virtual flash does not require every host in the cluster to have flash, but only hosts with flash devices can have cache devices configured. You can use virtual flash with existing VMware solutions such as vMotion, DRS and HA.
You can configure vSphere to enable ESXi host swapping to a solid-state disk (SSD). In high memory usage, host swapping is used to reclaim memory from virtual machines. vSphere randomly selects the virtual machine physical pages to be swapped out, compresses memory of the virtual machine pages that are targeted by ESXi to be swapped out, and lets you configure a swap cache on the SSD.