If your caching I/O filter uses local flash devices, before activating the filter, you need to configure a virtual flash resource, also known as VFFS volume, on your ESXi host.


Check with your I/O filter vendor to determine whether the virtual flash resource must be enabled.


  1. In the vSphere Web Client, navigate to the host.
  2. Click the Manage tab and click Settings.
  3. Under Virtual Flash, select Virtual Flash Resource Management and click Add Capacity.
  4. From the list of available flash drives, select one or more drives to use for the virtual flash resource and click OK.


The virtual flash resource is created. The Device Backing area lists all the drives that you use for the virtual flash resource.