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In a virtual desktop environment for end users, Horizon supports many different types of virtual workspaces. They tend to be grouped together under the term Virtual Desktop Infrastructure (VDI). However, the various types of virtual desktops have very different characteristics.
Full clones were the first type of clone used. The use of full clones requires no special tools. It is as simple as cloning a VM in vCenter. If the clone is a Windows VM it requires a Sysprep first, or changing the name and IP address before joining a domain. If Horizon is used, it creates unique clones.
This is also the largest clone type and requires individual updating. Each VM is a unique machine that must be managed.
PowerStore can perform data reduction to reduce the disk footprint, but the VM still needs regular updating. During Windows Update cycles, each VM must perform a full update.
The footprint of full clones is the largest before data reduction. There are no shared pages between machines.
Linked clones are the most common type of clone that is used by VMware Horizon. They can be the least I/O intensive. Persistent linked clones overall generate the least I/O. The small number of base images relative to the pool size reduces the number of disk pages accessed.
The update process is less impactful as only the base image runs Windows update. Then the VMs can be recomposed and the entire pool is updated to a new base image snapshot. This allows VMs to be updated very quickly and with minimal administrative input.
Going forward, linked clones do not have support in cloud environments. This prevents users from doing hybrid cloud deployments using this technology.
Instant clones are the fastest-growing clone type that is used with Horizon. The improvements in instant clone technology have enabled them to replace other clone type in most configurations. They are the most I/O intensive of the clone type. Each VM refreshes on every user logout. This has trade-offs.
The big advantage of instant clones is each machine is completely refreshed on every user logout to the base image. The update process can leverage this and update each VM to a new base image on refresh. This allows frequent updating of VMs without user interruption. The virtual machines deploy with the fresh base image on user logout.
The caveat is the load that is created while this process is happening. A correctly sized environment does not have an issue, but the CPU and disk requirements must be accounted for. The architecture in this document accounts for the extra load.
With the advantages of instant-clone deployment and updating, the time spent managing the environment is the lowest of the technologies. The end-user impact can also be one of the lowest.