Tuesday 12 April 2016

Flash Read Cache

Flash Read Cache Helps accelerating the performance by making use of Host Flash Devices for Cache.

FRC is created when the Virtual Machine is Powered on and Get Discarded when the VM is Powered off.

Data read requests are satisfied from Cache if configured and the Data Write requests are served by the backing storage which could be SAN/NAS.

To understand whether to make use of FRC we need to interpret our workload well in advance because it is not mandatory that all of our workloads will be benefited from Flash Read Cache.

FRC will cache data for both Read and write I/Os, moreover Write I/Os are always serviced by Underlying Storage so read intensive workloads can be benefited directly from Flash Read Cache.

Configured through Web Client by Selecting the Individual Esxi Host.

However in some cases we may be running some applications which are sharing underlying storage out of which one is Read Intensive application and other one is a Write Intensive application.

Definitely the application with more Read workloads can take direct advantage from the Flash Read Cache but Flash Read Cache can also help us improve the performance of the Write Intensive application by Decreasing the amount of I/O load on the underlying array.

Flash Read Cache is broadly divided into two components i.e Flash Read Cache Infrastructure which is a helping hand in Virtualizing the flash based devices and providing the integration capabilities with vSphere features like HA, DRS.

On the other hand the second component is Cache Software which is responsible for accelerating the Virtual Machine read operations without making any changes to the Virtual Machine.


  • vCenter Server 5.5 or Later.
  • vSphere Enterprise Plus License.
  • Esxi Host version 5.5 or Later.
  • Virtual Machine Version 10 or Later.
  • Only SSD to be used as cache.

For More Information Refer Working With Flash Devices

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