i am afraid you don't have many choices, you will need to use host based tools (robocopy). Using block tools will not accomplish what you are trying to do.  Stand up a temporary Windows box with the vhdx data drives, robocopy the data. When it's time to cut-over, stop SQL services, disable SQL services, perform final robocopy. Move OS vhd to new environent, replace OS in temporary Windows server with the one you just copied, attach vhdx files you robocopied to earlier and boot it up. Might need to bring those drives online in Disk Administrator since it's never seen those vhdx files before. Once drives are online, re-enable SQL services and reboot the box.  That's what i would do, good luck.
Hello,  I posted this in the everything microsoft forum as well, however, I am still unclear on what to do.  My issue:  Right now I have an old one node hyper-v cluster.  Even though the 2nd node is evicted, cluster services are still running. We are looking to reuse that host in our DR site so I have to migrate all of the VMs off of it on to another cluster(that is also hyper-v).  Both clusters are zoned to the same VNX. I simply want to move those vms, which have virtual HBAs connected and large luns presented. The VMs were created in a kind of non conventional fashion, not in VMM.  The vms are running windows 2012 standard, and the clusters are running 2012 r2.  I might be missing the point with all of the threads I have read, etc, however, I am still in the dark on how to move these successfully.  Thanks again in advance! Admingirl
Moving virtual hba connected vms from one hyper-v cluster to another on same 
array virtual