Your ESXi hosts can use a portion of a flash-backed storage entity as a swap cache shared by all virtual machines.
The host-level cache is made up of files on a low-latency disk that ESXi uses as a write-back cache for virtual machine swap files. All virtual machines running on the host share the cache. Host-level swapping of virtual machine pages makes the best use of potentially limited flash device space.
Depending on your environment and licensing package, the following methods of configuring the host-level swap cache are available. Both methods provide similar results.
You can create a VMFS datastore on a flash device, and then use the datastore to allocate space for the host cache. The host reserves a certain amount of space for swapping to the host cache.
If you have a vSphere license to set up a virtual flash resource, you can use the resource to configure the swap cache on the host. The host swap cache is allocated from a portion of the virtual flash resource.