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    XEN or KVM
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    XEN or KVM

    UmairUmair Member
    edited September 2016 in General

    Hello,

    Just wondering which virtualization I should go for on a new server I am getting. Would really appreciate your input.

    Before you jump and make it a "Xen vs KVM" thread, please see my requirement.

    • The server will be hosting a couple of VMs. All of them running CentOS/Debian. (i.e. don't need windows support / performance at all)
    • I want to use CentOS 7 as host node OS. (Could go for CentOS 6 if I had to) But no debian for host node.
    • The VMs will be utilizing public + private network. (some VM will just be DB servers)
    • Would really like to have the option to Live VM snapshots. (Not something I have right now, not an absolute must)

    So which virtualization would you think will have better performance OR less over head??
    Also if I want to get a GUI for this, would you recommend SolusVM or Virtualizor ??

    I have been using OpenVZ for somewhat similar setup. Works fine and really have no issue. This time, trying to see other options.

    PS. This is not to for "vps hosting". I only host a couple clients with custom setups. 80% of the time, I am the only one having server access.

    From what I am reading, XEN PVH would probably perform much better than KVM (for Unix based VMs). What do you think ??

    Thanks for your input.

    Comments

    • If this is a private setup, lxc/lxd might fit the bill with almost zero overhead.

      I like my uptime down low and my servers all hacked. Can see me droppin' twenty-fours with a router in the rack.
      Ya like ya Switch-Ports hot and ya servers all hacked. If ya pings real high and ya networks pitch black.

    • JarryJarry Member
      edited September 2016

      I was facing the same dilema. Tested both Xen and KVM for a few weeks and finally decided for KVM (Proxmox). Reason is simple: I prefer web-gui. Proxmox has it as default, while for Xen (XenServer) the only usable I found is XenOrchestra, with free version having rather complicated and user-unfriendly installation. One more point for Proxmox is built-in support for LXC-containers (XenServer supports natively only Docker).

      Concerning performance, I'd say Xen and KVM are comparable. True, KVM is type-2 hypervisor sitting on top of full-sized OS, but do not forget: Xen is pushing disk-I/O over dom0 (using linux drivers) too. Actually, it can not exist without dom0, so I'd say it is type-2 too...

      Thanked by 1Umair
    • Honestly for your use case, it literally will make no difference, in terms of management though, KVM has better tools (GUI/WUI) available, Xen has a better cli interface IMHO, most people dont take the time to learn it though.

      Thanked by 1Umair

      Had enough of the scams on lowendbox, lowendtalk is now being infiltrated by corruption so I have chosen to make an low end exit #lexit for now - you can find me HERE

    • Performance-wise in theory, Xen should do better, but marginally at best, in practice, the difference is small either way.
      Proxmox is a great tool. Good choice.

      Thanked by 1Umair

      Extremist conservative user, I wish to preserve human and civil rights, free speech, freedom of the press and worship, rule of law, democracy, peace and prosperity, social mobility, etc. Now you can draw your guns.

    • @Jarry said:
      I was facing the same dilema. Tested both Xen and KVM for a few weeks and finally decided for KVM (Proxmox).

      I will have to take a closer look at Proxmox. I have really not looking it before. I am currently using SolusVM (Just for the sake of having a GUI). But since its not been updated for a while, I thought I will give Virtualizor a try.

      The reason I am looking/asking all this is because of some comparison tests I read recently. Suggesting KVM is better for windows and Xen for Unix based setups when the performance is a concern. So I thought I will ask the experts :)

      @AnthonySmith said:
      Honestly for your use case, it literally will make no difference, in terms of management though, KVM has better tools (GUI/WUI) available, Xen has a better cli interface IMHO, most people dont take the time to learn it though.

      So you mean, no noticeable performance difference ?? Just different management experience.

    • AnthonySmithAnthonySmith Top Provider
      edited September 2016

      Yep, Xen is probably more configurable in general but only in cli, don't worry either way though, just use HVM or KVM, its very simple to migrate between them if you think you made a mistake 3 months down the line, go with your gut feeling knowing you have a do over :)

      Thanked by 1Umair

      Had enough of the scams on lowendbox, lowendtalk is now being infiltrated by corruption so I have chosen to make an low end exit #lexit for now - you can find me HERE

    • Maounique said: Proxmox is a great tool. Good choice.

      I totally, 100% agree. It's not CentOS, though.

      Thanked by 1Maounique

      I recommend Prometeus, the best provider ever!

    • Xen is good for customers/client and KVM is good for hosting company. Xen resource is dedicated and its a hard to oversell Xen so If you want a good performance and need stable server then xen is good else KVM.

      Cheap $9/Year Hosting(US/UK/Canada/ES) - Cheap Windows VPS Hosting from Dewlance & Linux Xen VPS at low price. PreMadeKb.com WHMCS/Blesta Readymade Knowledgebase
    • MaouniqueMaounique Member
      edited September 2016

      @DewlanceVPS said:
      Xen is good for customers/client and KVM is good for hosting company. Xen resource is dedicated and its a hard to oversell Xen so If you want a good performance and need stable server then xen is good else KVM.

      /facepalm

      mpkossen said: I totally, 100% agree. It's not CentOS, though.

      Even better, it is Debian :P

      Umair said: Suggesting KVM is better for windows and Xen for Unix based setups when the performance is a concern. So I thought I will ask the experts :)

      Xen does better in Unix, but this does not mean KVM is better for Windows.
      With the correct drivers and a fairly stable and tested branch, Windows is as good on Xen as it is on KVM if not better (my experience shows Windows is more stable on XenServer than Proxmox, at least the older stuff, like XP). Also, some people complained that proxmox bios emulation is not working with some windows "loaders", albeit i presume there are still ways to circumvent anti-piracy measures from Microsoft.

      Thanked by 1Umair

      Extremist conservative user, I wish to preserve human and civil rights, free speech, freedom of the press and worship, rule of law, democracy, peace and prosperity, social mobility, etc. Now you can draw your guns.

    • @DewlanceVPS said:
      Xen is good for customers/client and KVM is good for hosting company. Xen resource is dedicated and its a hard to oversell Xen so If you want a good performance and need stable server then xen is good else KVM.

      Xen can also be oversold as easily as KVM. If the control panel you use doesn't support overselling, it does not automatically mean the hypervisor lacks it.

    • ZeastZeast Member
      edited September 2016

      @mpkossen said:

      Maounique said: Proxmox is a great tool. Good choice.

      I totally, 100% agree. It's not CentOS, though.

      Based on Debian
      https://pve.proxmox.com/wiki/Install_Proxmox_VE_on_Debian_Jessie
      https://pve.proxmox.com/wiki/Install_Proxmox_VE_on_Debian_Wheezy

      yyyyyy

    • @Shoaib_A said:

      @DewlanceVPS said:
      Xen is good for customers/client and KVM is good for hosting company. Xen resource is dedicated and its a hard to oversell Xen so If you want a good performance and need stable server then xen is good else KVM.

      Xen can also be oversold as easily as KVM. If the control panel you use doesn't support overselling, it does not automatically mean the hypervisor lacks it.

      Talk me through that then without the balloon driver viable in the domU ?

      Had enough of the scams on lowendbox, lowendtalk is now being infiltrated by corruption so I have chosen to make an low end exit #lexit for now - you can find me HERE

    • JarryJarry Member
      edited September 2016

      memory-ballooning is not the only way of dealing with overprovisioned HW (especially RAM). Some of others are memory-page sharing, memory-page compression, hypervisor-swapping, etc (for these to work, no special driver in VM/domU is required).

      I do not know which of them is Xen/KVM using. Just want to say even without balloon-driver you could still oversell RAM, and live with it.

    • Shoaib_AShoaib_A Member
      edited September 2016

      @AnthonySmith said:

      @Shoaib_A said:

      @DewlanceVPS said:
      Xen is good for customers/client and KVM is good for hosting company. Xen resource is dedicated and its a hard to oversell Xen so If you want a good performance and need stable server then xen is good else KVM.

      Xen can also be oversold as easily as KVM. If the control panel you use doesn't support overselling, it does not automatically mean the hypervisor lacks it.

      Talk me through that then without the balloon driver viable in the domU ?

      I do not have much experience with Xen but a couple of times I have run it for testing purposes I was able to overcommit disk space using qcow2 with Virtualizor. One of my friends who is in love with Xen also demonstrated to me that memory can also be over-subscribed with balloon driver.

      The point here is that it is possible to oversell disk as well as memory on Xen where as @DewlanceVPS claims it is not. It has been 2 years since RHEL/CentOS 7 came out but the control panel he is using does not offer any support for it as a host system. If some member here posts about performance & stability benefits you get by using an OS with kernel 3.1+ what is he going to say, there has been no kernel after 2.6.32? It seems he is quite experienced & his hosting company has lasted for many years so he should think & research before posting such things. And this is not the first time he has done it, he always tries to gave same impression whenever he posts in a Xen vs KVM discussion

      Thanked by 1tux
    • @Shoaib_A said:
      The point here is that it is possible to oversell disk as well as memory on Xen where as @DewlanceVPS claims it is not. It has been 2 years since RHEL/CentOS 7 came out but the control panel he is using does not offer any support for it as a host system. If some member here posts about performance & stability benefits you get by using an OS with kernel 3.1+ what is he going to say, there has been no kernel after 2.6.32? It seems he is quite experienced & his hosting company has lasted for many years so he should think & research before posting such things. And this is not the first time he has done it, he always tries to gave same impression whenever he posts in a Xen vs KVM discussion

      OP said in thread "would you recommend SolusVM or Virtualizor ??
      "

      How OP can oversell Disk/RAM using SolusVM or Virtualizor? SolusVM does not allow to oversell RAM/Disk. ;)

      Cheap $9/Year Hosting(US/UK/Canada/ES) - Cheap Windows VPS Hosting from Dewlance & Linux Xen VPS at low price. PreMadeKb.com WHMCS/Blesta Readymade Knowledgebase
    • @DewlanceVPS said:

      OP said in thread "would you recommend SolusVM or Virtualizor ??
      "

      How OP can oversell Disk/RAM using SolusVM or Virtualizor? SolusVM does not allow to oversell RAM/Disk. ;)

      Virtualizor does support qcow2, raw & thin-lv so disk can be oversold but this what you said

      @DewlanceVPS said:
      Xen is good for customers/client and KVM is good for hosting company. Xen resource is dedicated and its a hard to oversell Xen so If you want a good performance and need stable server then xen is good else KVM.

      Whereas other people who have used both for considerable time have said that there is hardly any difference in performance. OP also liked comments made before your first post in this this thread suggesting Proxmox & other alternatives which suggests the OP is open to suggestions. If a host is using a control panel which does not have latest features it does not mean that the alternatives also lack those or they don't exist at all just like I have never been to Singapore but it does not mean others also haven't or Singapore doesn't exist at all.

    • @Shoaib_A said:

      Virtualizor does support qcow2, raw & thin-lv so disk can be oversold but this what you said

      I use XEN from many years and overselling XEN means degrading your server. It will be unstable and crash issue will be occurred frequently while KVM allow you to oversell RAM but server will be stable.

      Cheap $9/Year Hosting(US/UK/Canada/ES) - Cheap Windows VPS Hosting from Dewlance & Linux Xen VPS at low price. PreMadeKb.com WHMCS/Blesta Readymade Knowledgebase
    • @Shoaib_A said:

      You can't oversell/over commit ram in Xen sorry, you can only borrow from one container and give to another, it's pre allocated on boot without the balloon driver, when you use the balloon driver the end use can see that.

      I mean you can use PV only and nest it in VMware, but that's not really overselling on Xen.

      Disk .. Ok yeah, but again that is nothing to do with Xen, it's a feature of qemu or lvm you are using to present an artificial reality to the hyper visor.

      Had enough of the scams on lowendbox, lowendtalk is now being infiltrated by corruption so I have chosen to make an low end exit #lexit for now - you can find me HERE

    • relookrelook Member
      edited September 2016

      Go for KVM and if you want to try the "taste" of cloud use OpenStack Mitaka as

      Your environment and you'll have private network, LBaaS, FWaaS, VPNaaS, custom

      Stacks and many more features all from CLI and nice GUI (Horizon).

      • Use PackStack all in one setup
    • @AnthonySmith said:

      @Shoaib_A said:

      You can't oversell/over commit ram in Xen sorry, you can only borrow from one container and give to another, it's pre allocated on boot without the balloon driver, when you use the balloon driver the end use can see that.

      I mean you can use PV only and nest it in VMware, but that's not really overselling on Xen.

      Disk .. Ok yeah, but again that is nothing to do with Xen, it's a feature of qemu or lvm you are using to present an artificial reality to the hyper visor.

      I have not used Xen enough to make any substantial claims but I felt my KVM VMs performing better as compared to when they were running Xen on same hardware. Linode also claimed that 3x performance boost & versatility were the main reasons behind moving away from Xen and adopting KVM. They also claimed that KVM has much less overhead then Xen. And if someone thinks that overselling in order to save resources is not even a consideration for all those top of the list vps & "cloud" providers then I think he lives in his own imaginary world.

    • Shoaib_AShoaib_A Member
      edited September 2016

      @DewlanceVPS said:

      @Shoaib_A said:

      Virtualizor does support qcow2, raw & thin-lv so disk can be oversold but this what you said

      I use XEN from many years and overselling XEN means degrading your server. It will be unstable and crash issue will be occurred frequently while KVM allow you to oversell RAM but server will be stable.

      That is just your myth as every host in the world oversells to some extent no matter what virtualization technology they use. Also, overselling isn't limited to hosting industry only.
      For example, a fitness center has capacity for 60 members at one time, yet they sell 300 memberships knowing that all 300 members won't be using the facility at the same time. You can compare this to the hosting industry, although overselling 5x would likely be harmful, overselling a little bit can be smart because not all users will be using the bandwidth, CPU, or RAM at the same time.

      Non-oversold server with 30 1GB virtual servers:

      Intel Xeon

      32GB of RAM

      4xRAID10

      Oversold server with 60 1GB virtual servers:

      Same Intel Xeon

      64GB of RAM

      2xRAID1

      In this scenario, Hypervisor be it Xen or KVM would have no limitations, but the CPU and Disk I/O would be exhausted long before the 64GB of RAM. In fact, disk I/O is the most common bottleneck in VPS nodes.

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