Hello,   The disk you are using is not a supported disk. In addition, I would expect rather slow performance from a hard disk with that RPM speed, unfortunately. You can look in OpenManage to see if the virtual disk is being rebuilt, but it is possible that the disk just won't perform well, unfortunately.
I have swapped the original dual hard disks (1TB 7,2) from our small T130 and replaced with WD Red 4TB. Created new virtual disk RAID 1 mirroring and installed Hyper-V then fired a VM. Performance is unacceptable!!! Is bad performance only due to the new drives which are not suitable for server performance (5400RPM BTW) or is the system building the mirroring in the background? 
RAID Virtual disks performance