In vSphere, you can configure ESXi hosts to cache virtual machine disk data. This feature, called Horizon Storage Accelerator, uses the Content Based Read Cache (CBRC) feature in ESXi hosts. Horizon Storage Accelerator improves Horizon 7 performance during I/O storms, which can take place when many virtual machines start up or run anti-virus scans at once. The feature is also beneficial when administrators or users load applications or data frequently. Instead of reading the entire OS or application from the storage system over and over, a host can read common data blocks from cache.

By reducing the number of IOPS during boot storms, Horizon Storage Accelerator lowers the demand on the storage array, which lets you use less storage I/O bandwidth to support your Horizon 7 deployment.

You enable caching on your ESXi hosts by selecting the Horizon Storage Accelerator setting in the Add vCenter Server wizard in Horizon Console, as described in this procedure.

Make sure that Horizon Storage Accelerator is also configured for individual desktop pools. To operate on a desktop pool, Horizon Storage Accelerator must be enabled for vCenter Server and for the individual desktop pool.

Horizon Storage Accelerator is enabled for desktop pools 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 new 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.

You can enable Horizon Storage Accelerator on desktop 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 Horizon Storage Accelerator.

Horizon 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 Horizon 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. Hence, this combination is tested and supported.

Important: If you plan to use this feature and you are using multiple Horizon 7 pods that share some ESXi hosts, you must enable the Horizon Storage Accelerator feature for all pools that are on the shared ESXi hosts. Having inconsistent settings in multiple pods can cause instability of the virtual machines on the shared ESXi hosts.

Prerequisites

  • Verify that your vCenter Server and ESXi hosts are version 5.1 or later.

    In an ESXi cluster, verify that all the hosts are version 5.1 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 document that describe Horizon 7 and Horizon Composer privileges required for the vCenter Server user.

Procedure

  1. In Horizon Console, navigate to Settings > Servers.
  2. On the vCenter Server tab, click Add and complete the Add vCenter Server wizard pages that precede the Storage Settings page.
  3. On the Storage Settings page, select Enable Horizon Storage Accelerator.
    This option is selected by default.
  4. Specify a default host cache size.
    The default cache size applies to all ESXi hosts that are managed by this vCenter Server instance.

    The default value is 1,024MB. The cache size must be between 100MB and 2,048MB.

  5. To specify a different cache size for an individual ESXi host, select an ESXi host and click Edit cache size.
    1. In the Host cache dialog box, check Override default host cache size.
    2. Type a Host cache size value between 100MB and 2,048MB and click OK.
  6. On the Storage Settings page, click Next.
  7. After reviewing the settings on the Ready to Complete page, click Submit.

What to do next

Configure settings for client sessions and connections. See, "Configuring Settings for Client Sessions," in the Horizon 7 Administration document.

To complete Horizon Storage Accelerator settings in Horizon 7, configure Horizon Storage Accelerator for desktop pools. See "Configure Horizon Storage Accelerator for Desktop Pools" in the Setting Up Virtual Desktops in Horizon Console document.