vFRC is server side read cache from local SSD devices .These SSDs can be either PCIe flash cards or SSD attached to a local disk controller. By utilizing local flash storage, vSphere Flash Read Cache (vFRC) brings a large, low latency read cache to applications requiring high levels of physical reads.
This read cache layer is fully transparent to individual virtual machines and requires no in-guest configuration or agents to take advantage of the cache. vFRC uses a write-through cache mechanism that synchronously writes to both the cache and the backend storage. vFRC is configured on a per VMDK basis, thereby affording fine grained control over which IO devices receive the caching resources.
- VM Version should be 10
- You have enterprise Plush License
- Available in vSphere 5.5 or Later
- You have atleast one Local SSD or PCI Flash card for each ESXi Server and must not in use or mounted as datastore.
- This feature in only configurable from Web Client
- One Virtual Flash Filesystem (VFFS) per host
- Eight flash devices per VFFS
- 4 TB maximum individual flash device size
- Maximum 400 GB of vFRC per VMDK
- 32 TB of total vFRC per host
Step 1- Configure vFRC on ESXi hosts
To configure vFRC navigate to Host -> Manage -> Settings -> Virtual Flash -> Virtual Flash Resource Management -> Click on “Add Capacity”
Select your SSD Drive for vFRC -> Click “OK”
Verify you configured vFRC at ESXi Host.
Step 2- Configure vFRC on VM under the vFRC configured ESXi host.
To configure aVM for vFRC -> edit VM settings and expand the Hard Disk section for the VMDK that will receive the vFRC. You can set the size on Main setting screen or you can click on “Advanced hyperlink”. In advance you have option to set block size. When you are done -> Click “OK”
Verify the configured vFRC and Click “OK”
It is recommended to set the block size at minimum to the same value as the Oracle database block size.
While vMotion VM will only migrate if the contents of the cache can be copied to the destination host. Which will be the default option? If you choose not, then the vMotion will fail. If option two is chosen, the cache must be re-warmed upon migration of the VM to a different host.