You can configure Composer linked-clone desktop pools to enable ESXi hosts to cache virtual machine disk data. This feature, called View Storage Accelerator, uses the Content Based Read Cache (CBRC) feature in ESXi hosts. View Storage Accelerator can reduce IOPS and improve performance during boot storms, when many machines start up or run anti-virus scans at once. The feature is also beneficial when administrators or users load applications or data frequently. To use this feature, you must make sure that View Storage Accelerator is enabled for individual desktop pools.
When a virtual machine is created, Horizon 7 indexes the contents of each virtual disk file. The indexes are stored in a virtual machine digest file. At runtime, the ESXi host reads the digest files and caches common blocks of data in memory. To keep the ESXi host cache up to date, Horizon 7 regenerates the digest files at specified intervals and when the virtual machine is recomposed. You can modify the regeneration interval.
You can enable View Storage Accelerator on pools that contain linked clones and pools that contain full virtual machines.
Native NFS snapshot technology (VAAI) is not supported in pools that are enabled for View Storage Accelerator.
View Storage Accelerator is enabled for a pool by default. The feature can be disabled or enabled when you create or edit a pool. The best approach is to enable this feature when you first create a desktop pool. If you enable the feature by editing an existing pool, you must ensure that a new replica and its digest disks are created before linked clones are provisioned. You can create a replica by recomposing the pool to a new snapshot or rebalancing the pool to a new datastore. Digest files can only be configured for the virtual machines in a desktop pool when they are powered off.
View Storage Accelerator is now qualified to work in configurations that use Horizon 7 replica tiering, in which replicas are stored on a separate datastore than linked clones. Although the performance benefits of using View Storage Accelerator with Horizon 7 replica tiering are not materially significant, certain capacity-related benefits might be realized by storing the replicas on a separate datastore. As a result, this combination is tested and supported.
- Verify that your vCenter Server and ESXi hosts are version 5.0 or later.
In an ESXi cluster, verify that all the hosts are version 5.0 or later.
- Verify that the vCenter Server user was assigned the Host > Configuration > Advanced settings privilege in vCenter Server. See the topics in the Horizon 7 Installation documentation that describe Horizon 7 and Composer privileges required for the vCenter Server user.
- Verify that View Storage Accelerator is enabled in vCenter Server. See the VMware Horizon Console Administration document.
- In Horizon Console, display the Advanced Storage Options page.
Option Description New desktop pool (recommended) Start the Add Pool wizard to begin creating an automated desktop pool. Follow the wizard configuration prompts until you reach the Advanced Storage Options page. Existing desktop pool Select the existing pool, click Edit, and click the Advanced Storage Options tab.
If you modify View Storage Accelerator settings for an existing desktop pool, the changes do not take effect until the virtual machines in the desktop pool are powered off.
- To enable View Storage Accelerator for the pool, make sure that the Use View Storage Accelerator check box is selected.
This setting is selected by default. To disable the setting, uncheck the Use View Storage Accelerator box.
- (Optional) Specify which disk types to cache by selecting OS disks only or OS and persistent disks from the Disk Types menu.
OS disks is selected by default.
If you configure View Storage Accelerator for full virtual machines, you cannot select a disk type. View Storage Accelerator is performed on the whole virtual machine.
- (Optional) In the Regenerate storage accelerator after text box, specify the interval, in days, after which the regeneration for View Storage Accelerator digest files take place.
The default regeneration interval is seven days.
What to do next
You can configure blackout days and times during which disk space reclamation and View Storage Accelerator regeneration do not take place. See #GUID-087CC137-637A-4224-B043-499C4C071AD3.
If you enable View Storage Accelerator by editing an existing pool, recompose the desktop pool to a new snapshot or rebalance the pool to a new datastore before linked clones are provisioned.