Linux – IPFire firewall under Hyper-V. How to get synthetic devices working

I also had a lot of issues with any mainline kernel hv starting with 2.6.33 up to recent 2.6.36.1. It seems that either you are of the lucky ones and can get working Linux VMs or what is more often seen are network losses and crashing storage modules. I hope things improve but at the moment I still have a bad feeling.

I have the certain doubt the hv modules were primarily developed and testest with Kernels from RHEL 5 (not 6) amd SLES 10. I had to switch CentOS 5 to get a stable running Linux.

See the problems that were reported here: http://www.panterlo.com/2010/10/10/ubuntu-10-10-and-hyper-v-r2/#comment-84

The synthetic drivers 'talk' more directly to the actual hardware, bypassing most of the hypervisor (for common data operations). This dramatically cuts down on the hypervisor overhead related to most network activity.

If your server doesn't communicate much on the network, or if your hardware is well undercommitted, you should be fine with the emulated drivers. There's definitely a performance penalty for doing this however.