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SC Series snapshots and Hyper-V
29 Dell EMC SC Series: Microsoft Hyper-V Best Practices | CML1009
3.2.2 Recover a guest VM on a cluster shared volume
The process of using SC Series snapshots to recover guest VMs that reside on a cluster shared volume
(CSV) is like the process of recovering a guest VM to standalone host, as detailed in the preceding section.
However, recovering a VM from a CSV may require changing the disk signature first.
Windows servers assign each volume a unique disk ID (or signature). For example, the disk ID for an MBR
disk is an 8-character hexadecimal number such as 045C3E2F4. No two volumes mapped to a server can
have the same disk ID.
When an SC Series snapshot is taken of a Windows or Hyper-V volume, the snapshot is an exact point-in-
time copy, which includes the Windows disk ID. Therefore, View Volumes created from an SC Series
snapshot will also have the same disk ID as the source volume.
With standalone Windows or Hyper-V servers, disk ID conflicts are avoided because standalone servers can
automatically detect duplicate disk IDs and change them dynamically without user intervention.
However, host servers are not able dynamically change conflicting disk IDs when disks are configured as
CSVs when the disks are mapped to two or more nodes concurrently.
When attempting to map a View Volume of a snapshot of a CSV back to any server in that same cluster, the
View Volume will cause a disk ID conflict, which can be potentially service-affecting.
There are a couple of ways of working around the duplicate disk ID issue as detailed below.
• Option 1: Map the View Volume of the CSV to another host that is outside of the cluster and copy the
guest VM files over the network to recover the guest.
• Option 2: Map the View Volume to another Windows host outside of the cluster and use Diskpart.exe
to change the disk ID. Once the ID has been changed, re-map the View Volume to the cluster. The
steps to use Diskpart.exe to change the disk ID are detailed below.
3.3 Change a cluster shared volume disk ID with Diskpart
Follow these steps to change a volume disk ID. PowerShell can also be used.
1. Access the standalone Windows host that the View Volume of the CSV will be mapped to.
2. Open a command window with administrator rights.
3. Type diskpart.exe and press Enter.
4. Type list disk and press Enter.
5. Make note of the current list of disks (in this example: Disk 0, Disk 1, Disk 2).
6. Use the Dell Storage Manager Client to map a View Volume of the CSV to this host.