6.0.1

Using Flash Devices with vSphere
In your vSphere environment, you can use ash devices for a variety of functionalities.
Table 14‑1. Using Flash Devices with vSphere
Functionality Description
Virtual SAN Virtual SAN requires ash devices. For more information, see the Administering
VMware Virtual SAN documentation.
VMFS Datastores You can create VMFS datastores on ash devices. Use the datastores for the
following purposes:
n
Store virtual machines. Certain guest operating systems can identify virtual
disks stored on these datastores as ash virtual disks. See “Identifying Flash
Virtual Disks,” on page 134.
n
Allocate datastore space for ESXi host swap cache. See “Conguring Host
Swap Cache,” on page 139
Virtual Flash Resource (VFFS) Set up a virtual ash resource and use it for the following functionalities:
n
Use as Virtual Flash Read Cache for your virtual machines. See Chapter 15,
“About VMware vSphere Flash Read Cache,” on page 141.
n
Allocate the virtual ash resource for ESXi host swap cache. This is an
alternative method of host cache conguration that uses VFFS volumes instead
of VMFS datastores. See “Congure Host Swap Cache with Virtual Flash
Resource,” on page 140.
n
If required by your vendor, use the virtual ash resource for I/O caching
lters . See Chapter 21, “Filtering Virtual Machine I/O,” on page 243.
Identifying Flash Virtual Disks
Guest operating systems can identify virtual disks that reside on ash-based datastores as ash virtual
disks.
To verify if this feature is enabled, guest operating systems can use standard inquiry commands such as
SCSI VPD Page (B1h) for SCSI devices and ATA IDENTIFY DEVICE (Word 217) for IDE devices.
For linked clones, native snapshots, and delta-disks, the inquiry commands report the virtual ash status of
the base disk.
Operating systems can detect that a virtual disk is a ash disk under the following conditions:
n
Detection of ash virtual disks is supported on ESXi 5.x and later hosts and virtual hardware version 8
or later.
n
Detection of ash virtual disks is supported only on VMFS5 or later.
n
If virtual disks are located on shared VMFS datastores with ash device extents, the device must be
marked as ash on all hosts.
n
For a virtual disk to be identied as virtual ash, all underlying physical extents should be ash-
backed.
Marking Storage Devices
You can use the vSphere Web Client to mark storage devices that are not automatically recognized as local
ash devices.
When you congure Virtual SAN or set up a virtual ash resource, your storage environment must include
local ash devices.
vSphere Storage
134 VMware, Inc.