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.

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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:
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  1. To display the SAN policy, run the command:
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  1. Change the SAN policy to be online with the command:
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  1. To get summary information about each disk, run the command:
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  1. Select Disk 1 (currently offline disk) with the command:
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  1. Clear the read-only attribute for Disk 1 with the command:
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  1. Bring Disk 1 online with the command:
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