6.0.1

Table Of Contents

Using Flash Storage Devices with Cache I/O Filters

A cache I/O lter can use a local ash device to cache virtual machine data.

If your caching I/O lter uses local ash devices, before activating the lter, you need to congure a virtual

ash resource, also known as VFFS volume, on your ESXi host. While processing the virtual machine read

I/Os, the lter creates a virtual machine cache and places it on the VFFS volume.

SSD

SSDSSD

SSD

Flash

Storage

Devices

I/O Path

Flash

Storage

Devices

Cache Filter

Virtual

Machine

Cache

ESXi

Virtual Flash Resource (VFFS)

To set up a virtual ash resource, you use ash devices that are connected to your host. To increase the

capacity of your virtual ash resource, you can add more ash drives. An individual ash drive must be

exclusively allocated to a virtual ash resource and cannot be shared with any other vSphere service, such

as Virtual SAN or VMFS.

Flash Read Cache and caching I/O lters are mutually exclusive because both functionalities use the virtual

ash resource on the host. You cannot enable Flash Read Cache on a virtual disk with the cache I/O lters.

Similarly, if a virtual machine has Flash Read Cache congured, it cannot use the cache I/O lters.

vSphere Storage

246 VMware, Inc.