Horizon calculates different sizing formulas when you edit an existing desktop pool, or store replicas on a separate datastore, than when you first create a pool.

If you edit an existing pool and select datastores for the pool, Horizon creates new clones on the selected datastores. The new clones are anchored to the existing snapshot and use the existing replica disk. No new replicas are created.

Horizon estimates the sizing requirements of new clones that are added to the desktop pool. Horizon does not include the existing clones in the calculation.

If you store replicas on a separate datastore, the other selected datastores are dedicated to the OS disks.

Storage Sizing Formulas for Clone Disks When You Edit a Pool or Store Replicas on a Separate Datastore shows the formulas that calculate the estimated sizes of clone disks when you edit a pool or store replicas on a separate datastore.

Table 1. Storage Sizing Formulas for Clone Disks When You Edit a Pool or Store Replicas on a Separate Datastore
Data Type Selected Free Space (GB) Min Recommended (GB) 50% Utilization (GB) Max Recommended (GB)
OS disks Free space on the selected datastores Number of new VMs * (2 * memory of VM) Number of new VMs * (50% of replica disk + memory of VM) Number of new VMs * (100% of replica disk + memory of VM)

Example of a Storage Sizing Estimate When You Edit a Pool or Store Replicas on a Separate Datastore

In this example, the golden image virtual machine is configured with 1GB of memory. The golden image virtual machine's disk size is 10GB. A pool is created with 10 machines.

The OS disks are configured on a datastore that currently has 184.23GB of available space.

Example of a Sizing Estimate for Clone Disks When You Edit a Pool or Store Replicas on a Separate Datastore shows how the sizing formulas calculate estimated storage requirements for the sample pool.

Table 2. Example of a Sizing Estimate for Clone Disks When You Edit a Pool or Store Replicas on a Separate Datastore
Data Type Selected Free Space (GB) Min Recommended (GB) 50% Utilization (GB) Max Recommended (GB)
OS disks 184.23 10 * (2*1GB) =

20.00

10 * (50% of 10GB + 1GB) =

60.00

10 * (100% of 10GB + 1GB) =

110.00