I'm running Hyper-V on Windows Server 2016 in a chassis with multiple hard drives. Using the built in Windows copy utility, these are the speeds I'm seeing when copying files between driveson this server under the following 2 scenarios:
1) Copying from one 8TB Red drive to another 8TB Red drive - 130-140 MB/s.
2) Copying from one 400GB HGST SAS SSD drive to a 8TB Red drive - 400-420 MB/s.
I also have multiple VM's on those 400GB SSD drives and when I RDP into one of them and copy a file from within the VM to one of those same 8TB Red drives (via a mapped drive) my speed maxes out at around 113MB/s. This copy scenario matches scenario 2 from above (ie file copied from 400GB SSD to 8TB SATA), but the speed is over 3x slower than what I see on the host.
Does anyone know why the copy speed from within my Guest VM to the Host is so much slower than when copying between the same drives Host to Host? Is there anything I can do in that VM to ensure my copy speeds approach the 400-420 I saw on the Host?