Administration

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Enable virtual machine disk space reclamation and configure View Storage Accelerator for Horizon 7.
Allow vSphere to Reclaim Disk Space in Linked-Clone Virtual
Machines
In vSphere 5.1 and later, you can enable the disk space reclamation feature for Horizon 7. Starting in
vSphere 5.1, Horizon 7 creates linked-clone virtual machines in an efficient disk format that allows ESXi
hosts to reclaim unused disk space in the linked clones, reducing the total storage space required for
linked clones.
As users interact with linked-clone desktops, the clones' OS disks grow and can eventually use almost as
much disk space as full-clone desktops. Disk space reclamation reduces the size of the OS disks without
requiring you to refresh or recompose the linked clones. Space can be reclaimed while the virtual
machines are powered on and users are interacting with their remote desktops.
Disk space reclamation is especially useful for deployments that cannot take advantage of storage-saving
strategies such as refresh on logoff. For example, knowledge workers who install user applications on
dedicated remote desktops might lose their personal applications if the remote desktops were refreshed
or recomposed. With disk space reclamation, Horizon 7 can maintain linked clones at close to the
reduced size they start out with when they are first provisioned.
This feature has two components: space-efficient disk format and space reclamation operations.
In a vSphere 5.1 or later environment, when a parent virtual machine is virtual hardware version 9 or later,
Horizon 7 creates linked clones with space-efficient OS disks, whether or not space reclamation
operations are enabled.
To enable space reclamation operations, you must use Horizon Administrator to enable space
reclamation for vCenter Server and reclaim VM disk space for individual desktop pools. The space
reclamation setting for vCenter Server gives you the option to disable this feature on all desktop pools
that are managed by the vCenter Server instance. Disabling the feature for vCenter Server overrides the
setting at the desktop pool level.
The following guidelines apply to the space reclamation feature:
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It operates only on space-efficient OS disks in linked clones.
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It does not affect View Composer persistent disks.
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It works only with vSphere 5.1 or later and only on virtual machines that are virtual hardware version
9 or later.
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It does not operate on full-clone desktops.
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It operates on virtual machines with SCSI controllers. IDE controllers are not supported.
Native NFS snapshot technology (VAAI) is not supported in pools that contain virtual machines with
space-efficient disks.
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