VMware vFlash Read Cache (VFRC) Notes

• Available in vSphere 5.5 and 6.0 for basic caching solution
• VMware introduces vSphere APIs for IO Filtering (VAIO) in vSphere 6.0 U1 as a new API framework for third party’s innovation
• VAIO is not a feature or product.
• It seems that VMware has no plan to create new caching product based on VAIO
• VAIO can be used not only caching but also for replication
• Some third party product can provide more advanced caching solution (both read and write-back cache, e.g. PernixData FVP)
• Require Enterprise Plus License
• Use local SSDs (must be on the HCL) to form a new file system called VFFS (Virtual Flash File System) to provide two types of write through (read only) caching
• Per-VMDK cache
• Host Swap cache
• VFRC limitation (KB2057206)
• Default VRFC maximum size is 200GB. Can be set to 400GB
• Configuration
1. Set up VFRC resouce on a host
• vSphere Web Client, host, Manage, Settings, Virtual Flash Read Cache Resource Management, Add capacity
2. Allocate VFRC to a VM’s VMDK
• vSphere Web Client, VM,  Edit Settings, select and expand the hard disk,and enter the amount of VFRC
• The block size can impact performance, but it’s not easy to determine (see this post for detail)
3. Set up Host Swap Cache
• vSphere Web Client, host, Manage, Settings, under Virtual Flash, edit Virtual Flash Host Swap Cache Configuration, Enable virtual flash host swap cache and enter the amount