I have a Windows 2012 Server with Hyper-V that is managing several VMs.
I set up Windows Server Backup on Windows 2012 to backup W2012 OS and all VMs that it manages, but it fails with the following error:
The backup operation that started at '2015-01-07T03:00:31.906000000Z' has failed because the Volume Shadow Copy Service operation to create a shadow copy of the volumes being backed up failed with following error code '0x80780021'. Please review the event details for a solution, and then rerun the backup operation once the issue is resolved.
The backup destination is 2TB External USB HD that is directly attached to W2012 Server box.