A 100x Network Improvement with Xen and a Windows 7 VM

I had to transfer a 120GB file on our intranet recently from a Windows 7 VM running on a Xen hypervisor to a network drive. Imagine my horror to see that it was going to take over 6000 minutes to complete!  A quick calculation told me this was going to take over 4 days – not cool at all.

Other colleagues in the office seem to have had no trouble in the past so it had to be something wrong with my virtual machine running on a Xen Hypervisor.

After trying a few things I found this thread: http://serverfault.com/questions/378722/windows-server-2008-network-speed-slow-xen-3-4-3-hvm-iso.

I was already using the latest guest drivers for it, so that wasn’t the issue. So I then tried:

  • netsh int tcp set global chimney=disabled
  • netsh int tcp set global rss=disabled
  • netsh int tcp set global netdma=disabled
  • netsh interface tcp set global autotuning=disabled

This then gave the following:

netshParams

I also disabled anything that said “offlload” in the driver settings:

XenDriverProperties

A quick reboot and my transfer went from over 6000 minutes to under 60 mins. A significant improvement 🙂

I’m not sure what the exact setting fixed it, but it’s good enough for me…