Extremely slow file transfers to Hyper-V VM on local machine

Solution 1:

Most likely, you are seeing an issue with Virtual Machine Queues.

If you are running a Broadcom network adapter, you will need to disable Virtual Machine Queues. We just setup a new server, running Server 2012 Standard with Hyper-V, running two Server 2012 Standard guests, and saw the exact same thing you are describing. This seems to be an issue affecting Broadcom adapters.

Go into the Hyper-V host network properties, and look at the physical adapter, not the vEthernet. On the Advanced tab, scroll down to Virtual Machine Queues, and set it to disabled.

Once we made this change, things were flying.

Solution 2:

I had the same issue when running Hyper-V on with Broadcom NetXtreme I network adapters. I changed out the NICs to Intel and the network started to work as it should.

Here are the steps to diagnose the problem:

1. Measure current transfer speeds.
2. Install a Legacy Network adapter, remove the previous NIC on the guest VM.
3. Measure transfer speeds again.
4. If you find that there's a significant difference in speed (faster), it is your NIC.

In my case, I have tried different settings on the Network card before changing it out to an Intel. FYI, The Broadcom NetXtreme II network adapters works fine.

Solution 3:

OK, I had the problem of a comatose "local" copy from my Win7 32bit hyperv install hosted on Win8.1 64 bit.

Copy to any other share on the network was fine.

Changed the network inside the VM to use only IPV4 as it had defaulted to IPV6, and speed is now as expected