Servers may have the SAN Policy for new disks configured to “Offline,” meaning that when a VM is restored, its secondary drive(s) will be designated as “offline.” This can prevent the operating system from starting up.
For critical servers, such as Domain Controllers, the SAN policy should be configured to "OnlineAll". This can be done with "diskpart" from the command line:
Open the command prompt on the relevant VM.
Type diskpart to open the disk partition tool.
C:> diskpart
Type san to verify the SAN policy is set to “Offline Shared”.
DISKPART> SAN SAN Policy : Offline Shared
Type san policy=OnlineAll to set the policy to “OnlineAll”.
DISKPART> san policy=OnlineAll