6.5.1

Table Of Contents
The following vSphere functionalities require the virtual flash resource:
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Virtual machine read cache. See Chapter 16 About VMware vSphere Flash Read Cache.
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Host swap cache. See Configure Host Swap Cache with Virtual Flash Resource.
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I/O caching filters, if required by your vendors. See Chapter 23 Filtering Virtual Machine I/O.
Before setting up the virtual flash resource, make sure that you use devices approved by the VMware
Compatibility Guide.
Considerations for Virtual Flash Resource
When you configure a virtual flash resource to be used by ESXi hosts and virtual machines, several
considerations apply.
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You can have only one virtual flash resource, also called a VFFS volume, on a single ESXi host. The
virtual flash resource is managed only at the host's level.
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You cannot use the virtual flash resource to store virtual machines. Virtual flash resource is a caching
layer only.
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You can use only local flash devices for the virtual flash resource.
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You can create the virtual flash resource from mixed flash devices. All device types are treated the
same and no distinction is made between SAS, SATA, or PCI express connectivity. When creating the
resource from mixed flash devices, make sure to group similar performing devices together to
maximize performance.
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You cannot use the same flash devices for the virtual flash resource and vSAN. Each requires its own
exclusive and dedicated flash device.
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The total available capacity of the virtual flash resource can be used by ESXi hosts as host swap
cache and by virtual machines as read cache.
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You cannot select individual flash devices for swap cache or read cache. All flash devices are
combined into a single flash resource entity.
Set Up Virtual Flash Resource
You can set up a virtual flash resource or add capacity to existing virtual flash resource.
To set up a virtual flash resource, you use local flash devices connected to your host. To increase the
capacity of your virtual flash resource, you can add more devices, up to the maximum number indicated
in the Configuration Maximums documentation. An individual flash device must be exclusively allocated to
the virtual flash resource. No other vSphere service, such as vSAN or VMFS, can share the device with
the virtual flash resource.
Procedure
1 In the vSphere Web Client, navigate to the host.
2 Click the Configure tab.
vSphere Storage
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