Regenerating digest files for View Storage Accelerator and reclaiming virtual machine disk space can use ESXi resources. To ensure that ESXi resources are dedicated to foreground tasks when necessary, you can prevent the ESXi hosts from performing these operations during specified periods of time on specified days.

For example, you can specify a blackout period during weekday morning hours when users start work, and boot storms and anti-virus scanning I/O storms take place. You can specify different blackout times on different days.

Disk space reclamation and View Storage Accelerator digest file regeneration do not occur during blackout times that you set. You cannot set separate blackout times for each operation.

Horizon allows View Storage Accelerator digest files to be created for new machines during the provisioning stage, even when a blackout time is in effect.

The following procedure applies to instant-clone desktop pools.


  • Verify that Enable View Storage Accelerator, Enable space reclamation, or both features are selected for vCenter Server.
  • Verify that Use View Storage Accelerator, Reclaim VM disk space, or both features are selected for the desktop pool.


  1. On the Advanced Storage Options page in the Add Pool wizard, go to Blackout Times and click Add.
    If you are editing an existing pool, click the Advanced Storage Options tab.
  2. Check the blackout days and specify the starting and ending times.
    The time selector uses a 24-hour clock. For example, 10:00 is 10:00 a.m., and 22:00 is 10:00 p.m.
  3. Click OK.
  4. To add another blackout period, click Add and specify another period.
  5. To modify or remove a blackout period, select the period from the Blackout times list and click Edit or Remove.