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which virtualization technology VM do you like provide?
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which virtualization technology VM do you like provide?

Some people say Xen is more stable than KVM,but from my production server exprience, KVM even Openvz is more stable than Xen.

Because of Xen's Dom0 and DomX,you can't analyze your server's status easily,your only tool is xentop.

another problem is the number of VM host.I use a 72GB server as Xen virtualization server.Everytime xen VMs up to 60+,you can't create any more VM,some strange problem happens. But other KVM server,total VM number can up to 90+ and runs also very stable.

I will never use Xen any more.KVM seems be a good virtualization technology.

Comments

  • charliecharlie Member, Host Rep

    We use several Xen servers, some servers have 100+ VM-s (this is a private VM-s, not VPS service), and it stable like rock.

  • AnthonySmithAnthonySmith Member, Patron Provider

    Xen has serious separation and reserves dedicated resources for the dom0 (if configured properly) so it is very rare that any individual VPS on a Xen node would actually impact the host, KVM on the other hand runs VM's in user space... so yeah unlikely to be as stable under pressure.

    The xm/xl toolstacks are pretty good imo I have Xen servers with 900+ day uptime.

    I would suggest your not using Xen properly or are trying to over allocate which you cant do in Xen especially as the extent of the info on your issue extends to "some strange problem happens"

    Anyway... KVM is nice and simple, not as mature or stable (as xen anyway) but wins on the performance side of things and is more friendly to the inexperienced.

  • drserverdrserver Member, Host Rep

    said: Some people say Xen is more stable than KVM,but from my production server exprience, KVM even Openvz is more stable than Xen.

    Not true at all. Server is stable as you can keep it stable. Stability is dictated by admin in most of the cases.

    said: Because of Xen's Dom0 and DomX,you can't analyze your server's status easily,your only tool is xentop.

    Not true at all again. You can use whatever you wish to monitor your server or VMs. There is xentop, xe, xm and lots of libvirt based monitoring tools.

    said: another problem is the number of VM host.I use a 72GB server as Xen virtualization server.Everytime xen VMs up to 60+,you can't create any more VM,some strange problem happens. But other KVM server,total VM number can up to 90+ and runs also very stable.

    VM density is not dictated only with RAM. XEN has no limit in number of VMs, so there is something that you are doing something wrong. You can add tousand of VMs if you can support it with hardware.

    Out of curiosity, what kind of cpu and disk array are you using to support 90+ customers?

    Thanked by 1perennate
  • drserver said: Not true at all. Server is stable as you can keep it stable. Stability is dictated by admin in most of the cases.

    totally agree with you. :)

  • bobbybobby Member

    Common denominator for my vps' with highest uptime, are without a doubt Xen (PV), tho KVM are close (more provider dependent it seems).

    The NL nodes of @AnthonySmith are a good example:

    21:24:52 up 660 days, 8:54, 1 user, load average: 0.00, 0.01, 0.10

    ^ got same on 2 different nodes (Reboot from when he switched DC, I think). Except 1 ipv4 and 1 ipv6 network issue, those are spot on in actually "uptime".

    That, and the (almost) full virtualization, lands me on Xen.

  • dnwkdnwk Member

    LCX

  • raindog308raindog308 Administrator, Veteran

    I prefer MVS.

  • KVM or hyper-v

  • c0yc0y Member

    AnthonySmith said: Anyway... KVM is nice and simple, not as mature or stable (as xen anyway) but wins on the performance side of things and is more friendly to the inexperienced.

    Do note Qemu (KVM was a fork of Qemu, introduced virtualization extensions and some other interesting stuff but is now merged with Qemu) its purpose has always been primarily emulation, not separation / hosting.

    Don't get me wrong, Xen is awesome. They just have different main purposes and approaches. One caveat of Xen (and OpenVZ of course) is potential kernel exploits, but I guess that wouldn't be possible on PVHVM (and PVH?).

  • @AnthonySmith said:
    Xen has serious separation and reserves dedicated resources for the dom0 (if configured properly) so it is very rare that any individual VPS on a Xen node would actually impact the host, KVM on the other hand runs VM's in user space... so yeah unlikely to be as stable under pressure.

    The xm/xl toolstacks are pretty good imo I have Xen servers with 900+ day uptime.

    I would suggest your not using Xen properly or are trying to over allocate which you cant do in Xen especially as the extent of the info on your issue extends to "some strange problem happens"

    Anyway... KVM is nice and simple, not as mature or stable (as xen anyway) but wins on the performance side of things and is more friendly to the inexperienced.

    I didn't oversall RAM,actually I only use 30GB+ RAM(total is 72GB RAM) befor "some strange problem". xen kernel is from xen4centos, I don't know if the problem is beacuse xen4centos kernel.

  • @drserver said:
    Out of curiosity, what kind of cpu and disk array are you using to support 90+ customers?

    I use a 72GB RAM server with raid10, most of my clients is not "heavy user" ,just use VPS as VPN serve,so server load is not badly.

  • NDTNNDTN Member, Patron Provider, Top Host

    We use both VMWare and Hyper-v now, I could say I was impressed by I/O performance by Hyper-V, but with VMWare we have API to customize the control panel.

  • ProfforgProfforg Member
    edited July 2014

    said: but from my production server exprience, KVM even Openvz is more stable than Xen.

    I have the same result. Never success to set up Xen without tons of bugs and crashes. KVM and OpenVZ was always stable and OK for me. I like OpenVZ because it's super-easy for set up.

  • AnthonySmithAnthonySmith Member, Patron Provider

    yep I think the story here is, don't just expect to run a few commands and have Xen working fine, it is not a 2 click solution and expects that the admin has done some reading.

  • AnthonySmith said: yep I think the story here is, don't just expect to run a few commands and have Xen working fine, it is not a 2 click solution and expects that the admin has done some reading.

    If to fix Xen 'bugs' i need to read their 'manual'....i'll never use it) BTW i anyway will not use it ever, because i saw hosting providers on Xen. There are really less number of them, but on Xen HVM perfomance is so poor, that i can't imagine :) KVM/OpenVZ perfomance is much better.

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