An instant clone desktop pool is an automated desktop pool created from a golden image using the vmFork technology (called the instant clone API) in vCenter Server.

Instant clone replaces View Composer linked clone as the process for creating non-persistent desktops in Horizon 8. In addition to using the instant clone API from vCenter Server, Horizon 8 also creates several types of internal VMs (Internal Template, Replica VM, and Parent VM) to manage these clones in a more scalable way.

Instant clones share the virtual disk of the parent VM and consume less storage than full VMs. In addition, instant clones share the memory of the parent VM when they are first created, which contributes to fast provisioning. As users log into these cloned desktops, additional memory is consumed.

While the use of a parent VM is helpful in improving the provisioning speed, it does increase the memory requirement across the cluster. In some cases when the benefit of having more memory outweighs the increase in provisioning speed, Horizon 8 automatically chooses to provision instant clones directly from a replica VM without creating any parent VM. This feature is called Smart Provisioning. Smart Provisioning creates Instant Clones using one of the following provisioning schemes:
  • Mode A - Instant clones with parent VM
  • Mode B - Instant clones without parent VM

A single instant clone pool can have instant clones that are created with or without parent VMs. An Instant Clone desktop pool can be explicitly switched into a Mode A or Mode B provisioning scheme. See https://kb.vmware.com/s/article/81026 for details.

Computer-based group policy objects (GPOs) that require a reboot on the golden image VM do not apply to instant clones because instant clones are created in a powered-on state. To apply the golden image VM GPOs to instant clones, see Applying Computer-based GPOs that Require Reboot on Instant Clones below.

Instant clone desktop pools have the following benefits:

  • The provisioning of instant clones is fast.
  • Instant clones are always created in a powered-on state, ready for users to connect. Guest customization and joining the Active Directory domain are completed as part of the initial power-on workflow.
  • You can patch a pool of instant clones in a rolling process with zero downtime.

Compute Profiles for Instant Clone Desktop Pools

A compute profile of an instant clone desktop pool is the number of vCPUs and vRAM allocated to each desktop in a pool. When creating an instant clone desktop pool, the administrator must specify the golden image and snapshot, as described in the Worksheet for Creating an Instant-Clone Desktop Pool. By default, Horizon 8 inherits the compute profile of the selected snapshot to create the desktop pool. Previously, if an administrator wanted to create two different pools of instant clone virtual desktops that use the same OS image but have different VM compute profiles, they had to create and maintain two golden images or two snapshots. This complicates the management of images and makes patch updates more time-consuming. With the compute profile feature, administrators can override the default compute profile and specify the desired vCPU, vRAM, and cores per socket to create the desktop pool. In this way, the same golden image and snapshot can be used to create multiple desktop pools where each pool has a different VM compute profile.

Administrators can change the compute profile for a pool during one of the following workflows:

Applying Computer-based GPOs that Require Reboot on Instant Clones

Some computer-based GPOs are processed at Windows startup and typically require a reboot for them to be applied to the desktop. To apply these GPOs properly to instant clones, follow these steps:
  1. Create or update the computer-based policy settings in the target OU for the instant-clone desktops.
  2. Take a new snapshot of the existing parent VM (or create a new parent VM) in vCenter Server. Even if nothing has changed on the parent VM, this will publish a new base image for the clones, which then receive the GPOs created in the previous step.
  3. In the administration console, push a new image to update the existing pool (or create a new pool) of instant clones using the parent VM in vCenter Server and the new snapshot created in the previous step. The GPOs are then applied to the instant clones.
Note the following:
  • Changes to foreground GPOs always require re-publishing as described in the preceding steps.
  • To ensure that background policies are applied before user login, apply Always wait for the network at computer startup and logon ** and re-publish as described in the group solution policy. This policy is located at Computer Configuration\Administrative Templates\System\Logon.