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

In addition to using the instant clone API from vCenter Server, Horizon 7 also creates several types of internal VMs (Internal Template, ReplicaVM, and ParentVM) to manage these clones in a more scalable way.

Instant clones share the virtual disk of the parentVM and consume less storage than full VMs. In addition, instant clones share the memory of the parentVM 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 parentVM 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 7 automatically chooses to provision instant clones directly from a replicaVM without creating any parentVM. This feature is called Smart Provisioning. A single instant clone pool can have instant clones that are created with or without parentVMs.

An instant-clone desktop pool has the following key characteristics:

  • The provisioning of instant clones is faster than View Composer linked clones.
  • Instant clones are always created in a powered-on state, ready for users to connect to. Guest customization and joining the Active Directory domain are completed as part of the initial power-on workflow.
  • For dedicated instant-clone desktop pools, users are assigned a particular remote desktop and return to the same desktop at each login. When a user logs out, a resync operation on the golden image retains the VM name and the Mac IP address of the VM after logoff. You can optionally configure the instant-clone desktop pool to not refresh after log off.
  • For floating instant-clone desktop pools, users are assigned random desktops from the pool. When a user logs out, the desktop VM is deleted. New clones are created according to the provisioning policy, which can be on-demand or up-front.
  • With the push-image operation, you can re-create the pool from any snapshot of any golden image. You can use a push image to roll out operating system and application patches.
  • When clones are created, Horizon 7 selects a datastore to achieve the best distribution of the clones across the datastores. No manual rebalancing is necessary.
  • View storage accelerator is automatically enabled.
  • Transparent page sharing is automatically enabled.
  • Instant clones and Storage vMotion are compatible. When you create an instant-clone desktop pool on a Storage DRS datastore, the Storage DRS cluster does not appear in the list in the desktop pool creation wizard. However, you can select individual Storage DRS datastores.
  • In Horizon 7 version 7.0.3 or later, internal validation checks determine if the instant clone and internal template have valid IP addresses and a network connection. If a virtual machine has a NIC that cannot be assigned an IP address during provisioning, instant-clone provisioning fails.
  • You can add a Virtual Trusted Platform Module (vTPM) device to instant clone desktop pools.
    • To set up the Key Management Server cluster, which is a prerequisite, see Set up the Key Management Server Cluster in the vSphere Security document.
    • For compatibility requirements, see Securing Virtual Machines with Virtual Trusted Platform Module in the vSphere Security document.
    • The golden image used for vTPM Instant Clone pools must have VBS enabled when creating the VM, as well as the local security policy set to enable VBS inside the guest.
    • You can also select or deselect the option to add or remove a vTPM during a push-image operation.
  • You can vMotion instant clones that are configured with NVIDIA GRID vGPU without any impact to vGPU functionality.

Instant clones have the following compatibility requirements:

  • vSphere 6.0 Update 1 or later.
  • Virtual machine hardware version 11 or later.

As a best practice, configure distributed virtual switches in the vSphere environment. It is mandatory to configure distributed virtual switches in the vSphere environment for dedicated instant clones.

Instant clones have the following multi-LAN compatibility requirements:
  1. vSphere 6.0 Update 1 or later.
  2. ESXi 6.0 U1 or newer.
  3. Virtual distributed switch only. There is no support for the standard switch.
  4. Port group can be static, dynamic, or ephemeral.
In Horizon 7, instant clones have the following restrictions:
  • Instant-clone desktops cannot have persistent disks. Users can use network share or VMware App Volumes to store persistent user data. For more information about App Volumes, see https://www.vmware.com/products/appvolumes.
  • Virtual Volumes and VAAI (vStorage APIs for Array Integration) native NFS snapshots are not supported.
  • Sysprep and Quickprep are not available for desktop customization. Use ClonePrep, which is designed for instant clones.
  • Windows 8 or Windows 8.1 are not supported.
  • Persona Management is not available.
  • You cannot specify a minimum number of ready (provisioned) machines during instant-clone maintenance operations. This feature is not needed because the high speed of creating instant clones means that some desktops are always available even during maintenance operations.