This document provides design guidance for Citrix XenDesktop 5.5 deployments that leverage VMware vSphere versions 4 and 5. It should not be considered as a replacement for other XenDesktop design guidance, but rather an addendum that will assist in design decisions specifically related to using VMware vSphere as the hypervisor. For further planning guides, please refer to the XenDesktop Design Handbook.
In vSphere, a cluster is a construct that consists of multiple VMware ESXi hosts bound together to form a single entity for the purpose of management and high-availability. Hosts, within a cluster, usually share common resources so that virtual machines can be started on, or migrated between (vMotion) any host within the cluster where sufficient resources exist. Resource pools, which can be created within a cluster, allow administrators to subdivide a cluster configuration to create shared logical pools of CPU and memory resources and in some cases guarantee resource levels for certain groups. Based on the vSphere 5 Configuration Maximums, VMware supports up to 32 hosts and/or 3000 virtual machines in a single cluster and up to 1600 resource pools can be created per cluster.