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Xen vs Kvm. Which one is better?
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Xen vs Kvm. Which one is better?

uzaysanuzaysan Member

Question is the title. I found a server but ıts xen virtualization. I always heard kvm. But first time I hear xen. Which one is good?

Or better question without comparison: Is Xen good? Does it have dedicated resources like kvm?

Comments

  • t0ny0t0ny0 Member
    edited June 22

    I use both Xen and KVM. From a users perspective - I see no difference. Both give you access to the kernel, unlike ovz.
    Edit: There are two kinds of Xen and you need to know which one you use.

    tldr; - You want HVM not PV

    In my head - HVM compares to KVM, and PV compares to OpenVZ

    Here is something from the Xen Wiki at http://wiki.xenproject.org/wiki/XenOverview



    Xen supported virtualization types Xen supports running two different types of guests. Xen guests are often called as domUs (unprivileged domains). Both guest types (PV, HVM) can be used at the same time on a single Xen system. Xen Paravirtualization (PV) Paravirtualization is an efficient and lightweight virtualization technique introduced by Xen, later adopted also by other virtualization solutions. Paravirtualization doesn't require virtualization extensions from the host CPU. However paravirtualized guests require special kernel that is ported to run natively on Xen, so the guests are aware of the hypervisor and can run efficiently without emulation or virtual emulated hardware. Xen PV guest kernels exist for Linux, NetBSD, FreeBSD, OpenSolaris and Novell Netware operating systems. PV guests don't have any kind of virtual emulated hardware, but graphical console is still possible using guest pvfb (paravirtual framebuffer). PV guest graphical console can be viewed using VNC client, or Redhat's virt-viewer. There's a separate VNC server in dom0 for each guest's PVFB. Upstream kernel.org Linux kernels since Linux 2.6.24 include Xen PV guest (domU) support based on the Linux pvops framework, so every upstream Linux kernel can be automatically used as Xen PV guest kernel without any additional patches or modifications. See XenParavirtOps wiki page for more information about Linux pvops Xen support. Xen Full virtualization (HVM) Fully virtualized aka HVM (Hardware Virtual Machine) guests require CPU virtualization extensions from the host CPU (Intel VT, AMD-V). Xen uses modified version of Qemu to emulate full PC hardware, including BIOS, IDE disk controller, VGA graphic adapter, USB controller, network adapter etc for HVM guests. CPU virtualization extensions are used to boost performance of the emulation. Fully virtualized guests don't require special kernel, so for example Windows operating systems can be used as Xen HVM guest. Fully virtualized guests are usually slower than paravirtualized guests, because of the required emulation. To boost performance fully virtualized HVM guests can use special paravirtual device drivers to bypass the emulation for disk and network IO. Xen Windows HVM guests can use the opensource GPLPV drivers. See XenLinuxPVonHVMdrivers wiki page for more information about Xen PV-on-HVM drivers for Linux HVM guests.
    Thanked by 2uzaysan webcraft
  • KVM all the way! Depends on what you need, KVM usually comes at a higher cost.

    Thanked by 2o_be_one t0ny0
  • GodSpeedGodSpeed Member

    Before KVM became popular, the VPS virtualization of dedicated resources was Xen. Xen has many similarities in resource allocation and KVM, but the configuration adjustment is not very flexible, and the performance gap is not very different. Now Kvm has occupied the market. After all, Xen is too old.

    If you have used Linode's early VPS service, you will understand the difference between Xen and KVM.

  • jsgjsg Member

    For your purpose ("I want a VPS/VDS") there is none that is significant. Personally I like XEN better for reasons that are not relevant to the vast majority of users, but I happily use KVM too which has the advantage of a huge community and crowd supporting it.

    Thanks no.

  • WebProjectWebProject Member, Provider

    @GodSpeed said: After all, Xen is too old.

    and still stable and support all OS, compare to ovz old version had limitations.

    Thanked by 1GodSpeed
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  • TheLinuxBugTheLinuxBug Member
    edited June 23

    FYI HVM isn't really used anymore by Xen, it's instead just a custom version of quemu (KVM) that's setup to better run under the Xen environment and can be managed by xen tools. Functionally, there is almost no real difference between a KVM server and a recent Xen HVM instance for many versions now. The biggest difference with Xen is that is also provides the option to run your servers in PV mode (paravirtualized) which if your system is going to be Linux based will have a lot less overhead than HVM (KVM) will. So the gain from using Xen is that you can not only use full KVM virtualization but also run PV hosts at the same time in a mix. This can be nice if your running mostly Linux systems, as utilizing PV can cut down on resource overhead and can also provide slightly more performance as it balances CPU and IO resources a bit better (differently). For this reason, I actually prefer Xen for my stuff as I run mostly Linux based servers.

    my 2 cents.

    Cheers!

    Thanked by 1webcraft

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