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Tips for running OVZ inside KVM effectively

Tips for running OVZ inside KVM effectively

craigbcraigb Member
edited October 2012 in Help

So its come up a few times about running OVZ inside KVM.... @chief mentioned it previously a few times, most recently as an example way to 'bundle' your OS to make migrations between providers easier (in the context of those paying month to month).

The google summary seems to be: its doable and performance doesn't have to suck - but was hoping peeps that have experience doing this can share any tips.

In terms of efficient IO, is VT-D passthru possible thru all 3 layers?)

Assume a single IP for now (so port forwarding or similar network setup).


"Go cheap on rarely used things"



  • ZenZen Member

    From a hosts point of view.. what is regular for great I/O (and this is for big servers, but I wouldn't do nested virtualization on anything smaller in production ) I think many use 8-12 disk arrays, SSD caching to improve I/O, customized OVZ kernels which I cannot give information on. That's all I can think of right now after just waking up relating to performance, but that's from a hosts point of view.

    :) I am available for hire as a systems administrator, customer support technician levels 1-3, including managed support. Based in UK. Flexible time-zones and hours.

    Thanked by 1craigb
  • We played with it, the outcome is nasty.

    Maybe if you could use debian as the base OS with ext4 on the guest, it could pull some decent results. But then you need to find a panel that can run on debian.

    Thanked by 2craigb YKM
  • @GetKVM_Ash thanks Ash but don't need a panel - its for private use...

    "Go cheap on rarely used things"

  • miTgiBmiTgiB Member, Provider

    @GetKVM_Ash said: But then you need to find a panel that can run on debian.

    I know @Chief uses Proxmox in his KVM and loves it.

    Hostigation High Resource Hosting - SolusVM KVM VPS / Proxmox OpenVZ VPS- Low Cost Comodo SSL Certificates
    Thanked by 1craigb
  • JackJack Member, Provider

    @miTgiB's node work pretty good for it!

    I was getting 200MB/s through to the KVM box and the OVZ's inside it.

    Thanked by 1craigb
  • WilliamWilliam Member, Provider

    It works, not even so bad. No modifications needed except the NAT (can't comment on that, i always had enough IPs for it)

    Thanked by 1craigb
  • OpenVZ inside KVM? why not trying nested KVM? :D

    Yes! I'm with Carstensz Pyramid Server Now stop asking me please :D
    Thanked by 1craigb
  • Go for it with Debian then I'd say if your cool with just using vzctl at command line.

    Thanked by 1craigb
  • @Mon5t3r :) indeed...maybe I'll try that after to see just how hard the virt gods punish me ;p

    "Go cheap on rarely used things"

  • @craigb I would say that for best I/O performance you should make sure that VirtIO is enabled and set the Linux I/O scheduler to "noop". You can do that by editing grub.cfg or menu.lst (depending on your distro) and add to the "kernel" line "elevator=noop" - and of course reboot. You can also switch the scheduler on the fly but I would say that this is safer. By doing this I/O should pass trough all the layers down to the host node.

    Thanked by 1craigb
  • @marcm the IO scheduler tip looks very interesting - will try that out - thanks!

    "Go cheap on rarely used things"

  • It was just like someone saying or DamnVPS or ThrustVPS which is running vps inside a vps :D

    My blog| Raspibox - A website run in a Home Raspbery Pi server
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  • Heh, thinking about that, timing attacks would reveal that...

    "Go cheap on rarely used things"

  • I just remember i still have OWP installed in one of my testbed KVM. seems good so far, it's idling anyway but still good. :P

    Yes! I'm with Carstensz Pyramid Server Now stop asking me please :D
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