This task is relevant if you are using a vSphere version earlier than 6.7 on non-vSAN datastores.

Enabling periodic space reclamation on Horizon is a two-step process.

  • You must enable or disable space reclamation globally for each vCenter Server. You can configure space reclamation in Horizon Console by navigating to Settings > Servers. You can disable this feature on all desktop pools that are managed by the vCenter Server instance. Disabling the feature at this level overrides the setting at the desktop pool level.
  • After you enable space reclamation globally, you can enable or disable space reclamation at individual pool level.


Verify the following prerequisites for individual desktop pools.
  • Verify that the golden image has virtual hardware version 9 or later.
  • Verify that the storage for the pool uses SCSI controllers. Disk space reclamation is not supported on virtual machines with IDE controllers.
  • Verify that disk space reclamation is enabled in globally. This option ensures that the virtual machines in the pool are created in the efficient disk format that is required to reclaim disk space. It is available for instant clones and recommended for longer lived instant clone pools where the desktop is never refreshed on user logout. For other types of instant clones, the benefit from space reclamation may be insignificant.


  1. Complete these steps to set up space reclamation globally.
    1. In Horizon Console, navigate to Settings > Servers.
    2. On the vCenter Server tab, click Add, and navigate to the Storage Settings page.
    3. On the Storage Settings page, select Reclaim VM Disk Space.
      This option is selected by default if you perform a fresh installation of Horizon. You must select this option if you upgrade to a later release of Horizon.
  2. Complete these steps to set up space reclamation for individual desktop pools.
    1. In Horizon Console, navigate to the Desktop Pool Settings page of the instant clone pool creation wizard.
    2. Select the Reclaim VM disk space check box.
    3. In the Initiate reclamation when unused space on VM exceeds text box, type the minimum amount of unused disk space, in gigabytes, that must accumulate on an instant clone OS disk before ESXi starts reclaiming space on that disk.
      For example: 2 GB.
      The default value is 1 GB.

What to do next

You can configure blackout days and times during which disk space reclamation and regeneration for View Storage Accelerator do not take place. See Set Storage Accelerator and Space Reclamation Blackout Times.

In Horizon Console, you can select Inventory > Desktops and select a machine to display the last time space reclamation occurred and the last amount of space reclaimed on the machine.

You can use the vdmadmin -Moption to initiate disk space reclamation on a particular virtual machine for demonstration or troubleshooting purposes. See the Horizon Administration document.