This article describes an alternate method to Reverse Image Provisioning Services vDisks (XenServer Direct VHD Boot).

Note: Reverse imaging a Provisioning Services (PVS) vDisk is not the only way to get a vDisk back to your hypervisor for updates. This article explains the versatility associated with using native VHD format for vDisks and an alternate method to update your target disk. This method is also known as ‘Direct VHD Boot’.

Requirements

• Basic knowledge of import / export of virtual machines from your hypervisor

• Citrix Provisioning Services Server

• Administrative access to your hypervisors and Provisioning Services Site / Store

Background

Reverse imaging is a process where we copy all the contents of a vDisk back to a Virtual Machine (VM) on a hypervisor. Updates to Network drivers, target software, and so on, require execution on a non-provisioned VM (this also excludes private mode). This requires the reverse of imaging the VM for the first time to create a vDisk for Provisioning Services use. This process can sometimes be inconvenient, so this process informs administrators of how the VHD format adds flexibility when moving vDisks.

Instructions

• Taking an existing vDisk from a Provisioning Services store and returning it to a Hypervisor

• Exporting the vDisk from the Hypervisor to return to Provisioning Services

• Bypassing the Imaging Wizard

Taking an existing vDisk from a Provisioning Services store and returning it to a Hypervisor

1. If there are multiple versions on your current vDisk, merge to a new base disk.

   

2. When complete, find the latest full VHD file in your store.

   

3. Import this file into XenServer. (File > Import)
   Click About VM Import and Export for additional information on importing VMs.

   

4. XenServer creates a VM.

   

5. Choose Location, Storage, and Network settings for this VM.

6. After import, start the VM.

   This VM's identity is that of your master image. If it has been some time since the master image was started, you might be required to reset the trust with your domain.

7. Perform any required updates - XenDesktop Agent Software, Provisioning Services Target software, XenServer Tools, and so on. When complete, shut down the machine.

Exporting the vDisk from the Hypervisor to return to Provisioning Services

1. Export the VM out of XenServer.

   

2. Choose OVF/OVA Package as export type.

   

   Note: Do not choose any other options.

   

3. When exported, the two files VHD and OVF appears.

4. Copy the VHD file to your Provisioning Services store and rename it to something more descriptive.

   

5. From the Provisioning Services Console, left-click the store, then import the disk by clicking Add or Import Existing vDisk.

   

   Note: A warning message “Property file is missing...” might be displayed. This is an expected behavior.

   

6. Add the vDisk.

   

7. When imported, the vDisk properties are set to defaults. Ensure to adjust all settings as required. Replicate the settings of your previous vDisk if one existed.

8. Attach the vDisk to current target devices, use the XenDesktop Setup Wizard to create new targets, or use any other preferred method to create target devices. If using the XenDesktop Setup Wizard, detach the hard disk from your original VM (still on the hypervisor), then convert it to a Template.

Bypassing the Imaging Wizard

1. When target device software installation completes, clear Launch Imaging Wizard.

   

2. Click Finish.

3. Restart the computer, log on, and then run the Provisioning Services Optimization wizard (Recommended).

   

4. Shut down the VM.

5. Refer to Exporting the vDisk from the Hypervisor to return to Provisioning Services.

From these steps, it can be inferred how the vDisk that exists on your Provisioning Services store is an exact copy of the master VM created for Provisioning. This allows to move this vDisk back to the hypervisor and use it as it never left the original machine. It also demonstrates a secondary method to get the VM's disk to the Provisioning Services server for provisioning.

Note: Hyper-V also uses Microsoft’s native VHD format.