A farm is a group of Windows Remote Desktop Services (RDS) hosts. You can create published desktops associated with a farm. You can also deliver a published application to many users by creating application pools. The published applications in application pools run on a farm of RDS hosts.
Farms simplify the task of managing RDS hosts, published desktops, and applications in an enterprise. You can create manual or automated farms to serve groups of users that vary in size or have different desktop or application requirements.
A manual farm consists of RDS hosts that already exist. The RDS hosts can be physical or virtual machines. You manually add the RDS hosts when you create the farm.
Connection Server creates the instant clone virtual machines based on the parameters that you specify when you create the farm. Instant clones share a virtual disk of an internal parentVM and therefore consume less storage than full virtual machines. In addition, instant clones share the memory of a parentVM and are created using the vmFork technology.
Although helpful in speeding up the provisioning speed, the use of parentVM 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 automatically chooses to provision instant clones directly from replicaVM, without creating any parentVM. This feature is called Smart Provisioning. A single instant clone farm can have both instant clones that are created with parentVMs or without parentVMs.
When you create an application pool or a published desktop pool, you must specify one and only one farm. The RDS hosts in a farm can host published desktops, applications, or both. A farm can support at most one published desktop pool, but it can support multiple application pools. A farm can support both types of pools simultaneously.
For more information on farms, see the Horizon Administration document.