Microsoft Data Protection Manager (DPM) 2007 and 2010 allow online backups of Hyper-V guests, providing the guests and the Hyper-V server meet the necessary requirements as follows: –
http://technet.microsoft.com/en-us/library/dd347840.aspx
http://technet.microsoft.com/en-us/library/dd637102.aspx
There is another condition that I’ve encountered that causes a Hyper-V guest to report as “Backup Using Saved State” rather than “Backup Using Child Partition Snapshot”, where disks are marked as read-only.
In order to correct this, use diskpart to select the applicable disk and run “attrib disk clear readonly”, and then check that the Hyper-V guest reports as “Backup Using Child Partition Snapshot”.