What are the advantages of using Hyper-V's synthetic drivers with Linux VMs? RRS feed

  • Question

  • We are moving our virtualization platform from Citrix's XenServer to Hyper-V on Windows Server 2008 R2. As part of this project I need to migrate, in one form or another, some Debian Linux servers over to Hyper-V. I have successfully built a Debian-based server on our new Hyper-V platform and I'm beginning to test it.

    Debian 6 (Squeeze) uses the 2.6.32 kernel which includes the Hyper-V synthetic drivers, but it is not considered a supported operating guest operating system by Microsoft. I'm a little hesitant in trying to use them unless there's a compelling reason to, as other folks have had trouble

    • What advantages do the Hyper-V synthetic drivers offer over the emulated drivers?
    • For those of you who have experience with the Xen hypervisor, is using the synthetic drivers analgous to para-virtualizing a guest operating system?
    • Are then any noteworthy dangers or drawbacks of NOT using the synthetic drivers?

    Why should I bother to either a) deal with the reported instability of the Hyper-V drivers currently in the kernel, b) try to build a newer kernel, or c) try to make the Virtual Machine Additions work with a distribution they weren't designed for when everything seems to "just work"?

    • Edited by BrianEhMVP Monday, March 31, 2014 9:13 PM accurately reflect post
    • Moved by BrianEhMVP Monday, March 31, 2014 9:15 PM
    Monday, March 31, 2014 6:00 PM

All replies

  • 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.

    • Marked as answer by Cleland11 Monday, March 31, 2014 6:01 PM
    • Unmarked as answer by BrianEhMVP Monday, March 31, 2014 9:12 PM
    Monday, March 31, 2014 6:01 PM
  • The concept of synthetic drivers in xen is analogous to Hyper-V.

    The primary difference is that in xen - your VM must be a PV type VM - that xen paravirtualized kernel.  All VMs in Hyper-V are HVM type.  Hyper-V only supports HVM type VMs (in other words).

    Forwarding you to the appropriate forum for more.

    Brian Ehlert
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Monday, March 31, 2014 9:15 PM