XenServer: VDI is in use
XenServer: VDI is in use (but not really).
Find the VDI UUID for the disk:
xe vdi-list
Find the VBD UUID for it (first entry):
xe vbd-list vdi-uuid={VDI UUID}
Unplug the appropriate VBD:
xe vbd-unplug uuid={VBD UUID}
Destroy the VBD:
xe vbd-destroy uuid={VBD UUID}