Hi,
The requirements of using Flash Read Cache are:
- Ensure your environment is fully compatible with vSphere 5.5. You need a certified ESXi 5.5 host, vCenter Server 5.5, and a local SSD disk. To see if your hardware is compatible, see the VMware Hardware Compatibility Guide.
- Set up a Virtual Flash resource. For more information, see Setting up a Virtual Flash resource in vSphere 5.5 (2051647).
- Allocate Virtual Flash Read Cache to a virtual machine disk. For more information, see Allocating Virtual Flash cache to a virtual machine (2051572).
Do you meet these requirements? Also, it was a new feature to 5.5 and I am confident that it MUST be configured in the web client. I also have a feeling (casting my mind back to VCAP study) that the VM has to be of a certain hardware version (10). You can't assign vFRC feature to older VMs.