The instant clones feature leverages vSphere vmFork technology (available with vSphere 6.0U1 and later) to quiesce a running base image, or parent virtual machine, and hot-clone it to create a pool of up to 2,000 instant clones.
Not only do instant clones share the virtual disks with the parent virtual machine at the time of creation, instant clones also share the memory of the parent. Each instant clone acts like an independent desktop, with a unique host name and IP address, yet the instant clone requires significantly less storage. Instant clones reduce the required storage capacity by 50 to 90 percent. The overall memory requirement is also reduced at clone creation time.
Replica and Instant Clones on the Same Datastore
When you create an instant clone desktop pool, a full clone is first made from the master virtual machine. The full clone, or replica, and the clones linked to it can be placed on the same data store, or LUN (logical unit number).
Replica and Instant Clones on Different Datastores
Alternatively, you can place instant clone replicas and instant clones on separate datastores with different performance characteristics. For example, you can store the replica virtual machines on a solid-state drive (SSD). Solid-state drives have low storage capacity and high read performance, typically supporting tens of thousands of I/Os per second (IOPS).
You can store instant clones on traditional, spinning media-backed datastores. These disks provide lower performance, but are less expensive and provide higher storage capacity, which makes them suited for storing the many instant clones in a large pool. Tiered storage configurations can be used to cost-effectively handle intensive I/O scenarios such as simultaneous running scheduled antivirus scans.
If you use Virtual SAN datastores, you cannot manually select different datastores for replicas and instant clones. Because Virtual SAN automatically places objects on the appropriate type of disk and caches all I/O operations, there is no need to use replica tiering for Virtual SAN data stores. Instant clone pools are supported on Virtual SAN data stores. Instant clone pools are not supported on ordinary local storage disks.
Differences between Instant Clones and View Composer Linked Clones
Since instant clones can be created significantly faster than linked clones, the following features of linked clones are no longer needed when you provision a pool of instant clones:
Instant clone pools do not support configuration of a separate, disposable virtual disk for storing the guest operating system's paging and temp files. Each time a user logs out of an instant clone desktop, View automatically deletes the clone and provisions and powers on another instant clone based on the latest OS image available for the pool. Any guest operating systems paging and temp files are automatically deleted during the logoff operation.
Instant clone pools do not support the creation of a separate persistent virtual disk for each virtual desktop. Instead, you can store the end user's Windows profile and application data on App Volumes' user writable disks. An end user's user writable disk is attached to an instant clone desktop when the end user logs in. In addition, user writable disks can be used to persist user-installed applications.
Due to short-lived nature of instant clone desktops, the space-efficient disk format (SE sparse), with its wipe and shrink process, is not needed.