As users interact with linked clones, the clones' OS disks grow. A machine refresh operation restores the OS disks to their original state and size, reducing storage costs.
A refresh operation does not affect Horizon Composer persistent disks.
A linked clone uses less storage space than the parent virtual machine, which contains the complete OS data. However, a clone's OS disk expands each time data is written to it from within the guest operating system.
When Horizon Composer creates a linked clone, it takes a snapshot of the clone's OS disk. The snapshot uniquely identifies the linked-clone virtual machine. A refresh operation reverts the OS disk to the snapshot.
Horizon Composer can refresh a linked clone in as little as half the time it takes to delete and recreate the clone.
Apply these guidelines to refresh operations:
- You can refresh a desktop pool on demand, as a scheduled event, or when the OS data reaches a specified size.
You can schedule only one refresh operation at a time for a given set of linked clones. If you start a refresh operation immediately, the operation overwrites any previously scheduled task.
You can schedule multiple refresh operations if they affect different linked clones.
Before you schedule a new refresh operation, you must cancel any previously scheduled task.
- You can refresh dedicated-assignment and floating-assignment pools.
- A refresh can only occur when users are disconnected from their linked-clone desktops.
- A refresh preserves the unique computer information set up by QuickPrep or Sysprep. You do not need to rerun Sysprep after a refresh to restore the SID or the GUIDs of third-party software installed in the system drive.
- After you recompose a linked clone, Horizon 7 takes a new snapshot of the linked clone's OS disk. Future refresh operations restore the OS data to that snapshot, not the one originally taken when the linked clone was first created.
If you use native NFS snapshot (VAAI) technology to generate linked clones, certain vendors' NAS devices take snapshots of the replica disk when they refresh the linked clones' OS disks. These NAS devices do not support taking direct snapshots of each clone's OS disk.
- You can set a minimum number of ready, provisioned desktops that remain available for users to connect to during the refresh operation.
You can configure this option when you create a linked-clone desktop pool.