Fun with Hyper-V .vhdx (Including "Failed to Power on with Error 'General access denied error' (0x80070005). )

#1 - Can't mount .VHD(X) files on anything other than NTFS that I have tried, not even ExFAT!

#2 - You *CAN* use a symbolic link to a root VHD in one place, say a large HDD, so that the snapshots (and hence most of the write I/O) goes somewhere else. (Smaller SSD)

C:\Users\Public\Documents\Hyper-V\Virtual hard disks>mklink ServerEval.vhdx d:\SSDRedir\ServerEval.vhdx
symbolic link created for ServerEval.vhdx <<===>> d:\SSDRedir\ServerEval.vhdx

#2b - But permissions can get lost!

https://support.microsoft.com/en-us/help/2249906/hyper-v-virtual-machine-may-not-start-and-you-receive-a-general-access has the details.

Less-than-convenient part is that you can't copy the GUID from the pop-up error, have to grab it from event viewer, in Hyper-V Worker "Admin" events. (Thanks to https://www.mcbsys.com/blog/2010/10/hyper-v-virtual-machine-failed-to-start-after-copying-vhd/)

C:\Users\Public\Documents\Hyper-V\Virtual hard disks>icacls ServerEval* /grant "NT VIRTUAL MACHINE\7990B252-E0C9-469A-BDCE-5C1D7D75285A":(F)
processed file: ServerEval_963FFB8A-87A3-42DB-B1A2-0C332FCD0107.avhdx
processed file: ServerEval_B6B9ECD7-44DA-4595-B8E0-33235B624B46.avhdx
Successfully processed 2 files; Failed processing 0 files