Windows Disks go Offline After Reboot

Problem

Volumes attached to a running Windows guest becomes offline after reboot. The following warning is observed in the Windows disk management utility.

"The disk is offline because of policy set by an administrator"

Environment

  • Platform9 Managed OpenStack - All versions.

  • Nova

Cause

SAN policy has been introduced in Windows to protect shared disks accessed by multiple servers. By default, Windows machines will have the SAN policy set to be " Offline Shared", thus irrespective of the libvirt/ qemu or hardware version you may see this issue.

Resolution

  1. Open a command prompt from within the virtual machine.

  2. Run the diskpart utility by running the command:

diskpart.exe

  1. To display the SAN policy, run the command:

diskpart> sanSAN Policy: Offline Shared

  1. Change the SAN policy to be online with the command:

diskpart> san policy=OnlineAllDiskpart successfully changed the SAN policy for the current operating system.

  1. To get summary information about each disk, run the command:

diskpart>list diskDisk Status Size Free Dyn Gpt--------------- ------------------ ----------- ----------Disk 0 Online 40 GB 0 B*Disk 1 Offline 60 GB 1024 KB

  1. Select Disk 1 (currently offline disk) with the command:

diskpart>select disk 1Disk 1 is now the selected disk

  1. Clear the read-only attribute for Disk 1 with the command:

diskpart>attributes disk clear readonlydisk attributes cleared successfullydiskpart>attributes diskcurrent read-only state: noboot disk: nopagefile disk: nohibernation file disk: nocrashdump disk: noclustered disk: no

  1. Bring Disk 1 online with the command:

diskpart>online diskdiskpart successfully onlined the selected disk


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Windows Disks go Offline After RebootProblemEnvironmentCauseResolution