Okay, this was a bit of a puzzle:
A 2TB Seagate drive used for backups was originally formatted GPT on a Windows Server 2012 RTM Hyper-V host server.
We plugged the drive into a Windows Server 2012 R2 Hyper-V host to run backup recovery tests and ended up with the above. We tried a Windows 7 Enterprise system and the same result was to be had.
Getting a little concerned that any search results for the above stated to format the hard disk we tried one more thing. We plugged the drive into a Windows 8.0 Enterprise x64 machine to see if the VHDX files would show up.
Sure enough the drive received a letter and the files became available. Now to figure out how to get the newer server OS to read the drive!
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book
Chef de partie in the SMBKitchen
Find out more at