Well it seems that SVCMM has an issue with locally attached disks as a pass through disk.
We have a Microsoft Hyper-V server which we have a client running SBS2008 on it. We need to have a external USB disk connected to the server for backups using SBS backup tool (Windows Server Backup) our original thought was to just add another VHD file to the Child however we thought about this for a second and though, on restoring this may be a bit of an issue as we may not be able to mount that VHD to perform the restore, so, next bright idea is to use the External USB disk as a Pass Through Disk.
Unfortunatly when we were prepping the server we did not have the External USB disk, so we tested our theory with a small USB flash disk. We ran through the shutting down and adding the pass though it was added and seemed to work OK. So we removed the temporary flash disk and deployed the server. While on site the USB backup disk showed up was added to the Hyper-V server checked and then placed in offline mode so that SCVMM can use the disk.
SCVMM can not see the added disk, serer reboot power down remove and added the disk again still nothing in SCVMM, so back to Hyper-V Manager shut down the child added the disk and started it back up everything running all OK.
So back to why this happened, Hyper-V Manager can see and add the disk without issue however in SCVMM the Child Partition shows up as a SCSI adapter with no disks attached. After a bit more poking around I found the following error in SCVMM.
Error (1214): Virtual Machine name resides on a LUN, which cannot be found. ensure that the LUN, which contains virtual machine name, is unmasked to virtual machine host hostname. then try the operation again.
Well it seems that SCVMM think the drive is MASKED but it is not, an incompatibility with USB drives I think.
So back to the drawing board I think we may move back to using a VHD File instead.
Another strange one.