Configure vFlash Read Cache in vSphere 6

Virtual Flash Read Cache, also called as vFlash is an feature introduced in vSphere 5.5. It increases the performance of the Virtual Machines by making use of the local SSDs. Using vFlash increases the read speed for certain workloads.

vSphere Flash Read Cache is available only in Enterprise Plus Licensing.

There are two main components involved in this process.

Virtual Flash Cache

• Common reads are stored in the Virtual Flash cache.
• Created in the Virtual Flash Filesytems (VFFS).
• A virtual disk flat file used to store cached data whose size is equal to the amount of configured Virtual Flash Read Cache.

Virtual Flash Device

• Keeps track of the parts of the VMDK disk that are cached.
• Created in the Filesystem Device Switch (FDS).
• It reports if the requested I/O is cached or not and provides the optimal path to the data.

Source: VMware

Steps to Configure vSphere Flash Read Cache

Now that I have an 40GB SSD Storage attached to my Esxi Server, We are going to use that storage for the vSphere Read Flash Cache.

Open Web Client -> Host -> Configure -> Virtual Flash.

Click Add Capacity.

Select the local Flash Storage.

Click OK and you will see the File System configured.

Now you can configure the size of the Virtual Read Flash Cache.

I hope this helps you much in optimizing the performance of your VMs.