Persistent disks on dedicated instant clones allow the flexibility of storing user settings and other user-generated data on a disk independent of the VM.
Persistent Disk is a feature that existed on View Composer linked clones, which were deprecated in Horizon 8. Persistent disks are used as a secondary disk to store OS data and user information on virtual machines when the OS data is updated, refreshed, or rebalanced. Persistent disks are their own managed objects and are maintained without being tied to a particular VM, allowing VMware administrators the flexibility to set up persistent disks according to their needs, attaching to a VM and detaching from the VM when needed. All datastores support persistent disks.
- The persistent disk feature is available for dedicated desktops only.
- Persistent disks are not available for Linux based virtual machines as this feature uses Windows specific APIs.
- Persistent disks do not support a multi-user assignment.
- A desktop can have one primary persistent disk and zero to at least one secondary persistent disk.
- A secondary disk is similar to a primary disk and can be used to expand the storage capacity for a few users in a pool or give access to other users' primary disk to an admin or supervisor in case an employee moves out of the organization.
- Creating a pool with persistent disks:
- You can create a desktop pool with a primary persistent disk in the instant clone desktop pool creation workflow.
- When creating a pool with a persistent disk, you must specify a drive letter for the persistent disk and storage capacity in megabytes. Windows will redirect the user profile to this drive to store user information.
- Editing a pool with persistent disks:
- You can edit a persistent disk in the edit instant clone desktop pool workflow.
- You can change the drive letter and the size of the persistent disk.
- When you change the drive letter of the persistent disk, only the new desktops created will have the new drive letter.
- Deleting a pool with persistent disks:
- When you delete an entire desktop pool, the underlying persistent disks including any secondary disks are also deleted.
- If you want to retain the persistent disks, you must detach all the disks before deleting the pool.
- After the pool with persistent disks is created, VMware recommends that you add user or group entitlements to the desktop pool so that the persistent disk is associated with a user.
- For persistent disks to work successfully, the golden image VM must have a SCSI controller configured and present, as well as a device, such as a main hard disk, configured on the SCSI controller.
If you are using persistent disks with dedicated linked clones in a Horizon 7.x environment, consult this migration guidance on how you can move to Horizon 8 and continue to use persistent disks with dedicated instant clones: https://kb.vmware.com/kb/93091
For best practices and troubleshooting, see https://kb.vmware.com/kb/92881.
