An instant-clone desktop pool is an automated pool of non-persistent desktops created from a golden image using the vmFork technology (called the instant-clone API) in vCenter Server.
How VMware Horizon 8 Provisions Instant Clones
In addition to using the instant-clone API from vCenter Server, Horizon 8 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 where 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. A single instant-clone pool can have instant clones that are created with or without parent VMs.
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 Profile Feature 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, an administrator must specify the golden image and snapshot, as described in the Worksheet for Creating an Instant-Clone Linux Desktop Pool.
By default, Horizon 8 inherits the compute profile of the selected snapshot to create the desktop pool. 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.
