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Why do people pay more for KVM or XEN? - Page 2
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Why do people pay more for KVM or XEN?

2

Comments

  • @PhilND said: Any virtualization platform can have internal IP's, it's not hard to set it up.

    Besides, BuyVM, which providers offer this right now? It's "possible".

  • @vpsnodebox yeah we do use Solus and yeah we are considering a KVM switch as well, likely offer both as we have ~9 servers filled with OpenVZ at the moment, wouldn't want to turn all those folks on their heads. To much still to research, will look forward to its release before making a decision, will probably be a few months behind the release if we ever do make the switch.

  • @BigScoots the way to do it would be to set up new servers with KVM and offer it as Premium service for those who need to run FreeBSD, Windows, etc. - so that it won't conflict with current services. You don't want to have a massive migration either on your hands :)

  • @vpsnodebox yeah Windows is really the only reason we were looking into the switch at all. We dislike Windows, but there are those few clients really hounding us to make the offering. We shall see! I swore off Windows 10 years ago :(

  • @concerto49 said: Besides, BuyVM, which providers offer this right now? It's "possible".

    well the difference is that even if you set up internal IPs, the bandwidth transfer will still count - unlike BuyVM

  • While I love Mac OS X for desktop use, I put allot of money into this business so I will have to stick to my 48GB Windows 7 workstation for now... a Mac Pro with similar specs would be very expensive, even if I buy the RAM elsewhere.

  • for me, it's just the memory accounting. and more control also.

  • @winston said: well the difference is that even if you set up internal IPs, the bandwidth transfer will still count - unlike BuyVM

    Bandwidth is just cost. I'm more concerned with latency. Database replication would fail with latency that's too high. Same with Web application clusters with sticky sessions.

  • KuJoeKuJoe Member, Host Rep

    @concerto49 said: Besides, BuyVM, which providers offer this right now? It's "possible".

    SolusVM had this feature built in to it... but then they disabled it without telling anybody . I'm pretty sure once they add it back more people will offer it. Right now we manually assign internal IPs on request but it's not ideal since outgoing traffic still goes out the public IP without some custom iptables rules that I don't have the time or knowledge to setup.

  • KuJoeKuJoe Member, Host Rep
    edited August 2012

    @ErawanArifNugroho said: Is the OpenVZ/KVM/Xen is not the same with virtual machine? Like the one we created with VMWare?

    Sorry to ask, because I don't know about virtualization.

    OpenVZ and vServer are containers. They use the host's kernel and aren't true virtual machines like Xen, KVM, VMWare, etc...

    A container is a "virtual server" that cannot be altered outside the limits of the host (i.e. kernel, hardware, etc...). You are very limited on what you can do to the actual resources as most of the hardware is shared with the host.

    A virtual machine can be altered just like a real server (although Xen PV is paravirtualization so it's like the middle ground for a container and virtual machine but that's another discussion). You can use different NIC and disk drivers on a virtual machine, you can run non-linux kernels on a linux host, you can assign different hardware even if the host does not have that hardware (i.e. a floppy drive). Virtual machines also have their own BIOS and allow you to utilize network booting just like a real server.

    All of that being said, I prefer OpenVZ over Xen and KVM most of the time. There are a few times when I need Xen or KVM but it's so rare that I need one these days (although I'm keeping my Hostigation and BuyVM KVMs for those rare occasions).

    Thanked by 1ErawanArifNugroho
  • InglarInglar Member
    edited August 2012

    @BigScoots said: People like shiny things, KVM/XEN seem shiner to me.

    Please don't be so cruel :)

    Some things just don't work properly on OpenVZ, or don't work at all.

    So there is no choice in such cases.

  • @KuJoe said: I'm pretty sure once they add it back more people will offer it.

    Well maybe we'll start using it when the time comes. Still not enough VSwap and VSwap = more cost, so KVM might still be better in our case.

  • PhoenixVPSPhoenixVPS Member
    edited August 2012

    At least this isn't anywhere near as bad as Linux Flame Wars used to be. Linux vs. FreeBSD to this day is even worse. Virtualization Platform arguments are mild compared to that.

    @Jun The best argument that I can make for OpenVZ is that it is the ideal platform for a Low End VPS server since it won't take up any RAM for the kernel and the I/O performance is really good since it shares the same filesystem with everyone else.

  • You can't do this in OpenVZ:
    sync; echo 3 > /proc/sys/vm/drop_caches

    That's enough said :)

  • MaouniqueMaounique Host Rep, Veteran

    @Erawan : http://board.prometeus.net/viewtopic.php?f=8&t=851&sid=8c3adcbff2805f13872cc0f447a76067 First post is about virtualization types.
    I am also fan of OVZ when I buy, but at work use Xen, and it is not about isolation, it is simply proven mature technology that I use for years. OVZ may have more speed but Xen is not terribly slow either, especially since before I was using VMWare with it's terrible habit of writing the memory on disk...
    I also don't like admining OVZ, I am simply not into all those hacks to make it behave a bit like a real vm.
    As for KVM, well, I am not a RH fan, Xen is faster and has all I need, unlike VMWare wont become EOL or unsupported any time soon, no matter what for profit companies think.
    M

    Thanked by 1ErawanArifNugroho
  • I'm making a perhaps-fallacious logical leap here that if you can argue this hard about which is better without any clear winner, they're more or less equal except for edge cases*. People keep saying OVZ or KVM has better performance, but with no benchmarks, and nothing except "my friend said," or "this blog says," or, "I've used this one longer."



    *: e.g., Needing to run your own kernel for some reason, or iptables.

  • MaouniqueMaounique Host Rep, Veteran

    @Soylent said: People keep saying OVZ or KVM has better performance

    I think this one has no doubt, OVZ DOES have better performance on similar machines with similar numbers of VMs and similar load.
    Since it is really hard to test that in practice, there is some debate, but since KVM has WAY more overhead, then it is obvious it should perform worse.
    In practice, if it doesnt choke, OVZ is loaded more and more, KVM hits the wall faster.
    M

  • Maounique KVM has even lower virtualization overhead than Xen PV! The real issue is its I/O performance. Since it is real visualization it tends to treat its partition on the LVM as a real hard drive, so it will read and write only in-between the start and end sectors. KVM by itself is just a puny little Linux Kernel module.

  • i think the factor to choose which is on what you will use your vm for.

    Thanked by 1Inglar
  • Funny that no one talked about SELinux. That's my main concern for using KVM over OpenVZ.

  • komokomo Member
    edited August 2012

    I remember someone saying that XEN and/or KVM can be made secure in that way that the host (person) cannot open shell in XEN/KVM (make it behave more like a dedicated server). And OpenVZ is supposedly always open to the host.

    Is there some true in this? Maybe I did not explain it really well ;-).
    I think that an above-the-average privacy/security concerned person can find this important.

  • @komo there is no vzctl (lol) in KVM or Xen. The only way to peep inside the user's Xen PV VPS is to mount his VPS, make a tgz archive of it and then re-deploy it as a template. KVM is even more difficult as the only way that it may work is if you do a "dd". If you how ever just want to look at the user's files, than a simple mount will suffice. KVM partitions are mounted differently than Xen PV do.

  • Full Disk Encryption is possible on KVM.

  • lbftlbft Member

    OpenVZ's downsides, for me:

    • using IPv6 tunnel brokers is more hassle than on other platforms requiring tb-tun or similar, and you have to badger the host to set up tun/tap if they don't do it automatically/have an interface to do it yourself
    • can't load your own kernel, meaning that (for example) if the node's kernel doesn't have IPv6 support, then you can't even set up a tunnel broker
    • unless it's vswap, then the same process can have its memory usage counted significantly higher than on other platforms because of OpenVZ's funky memory accounting - meaning that I might be able to fit twice as many apps in the same memory on Xen or KVM, depending on how they use memory
    • there's the occasional app that can require tweaking of settings (e.g. Java sometimes) or that won't work at all (e.g. MongoDB without vswap)
    • you can't measure the amount of disk activity (e.g. iostat doesn't work at all, and iotop sometimes doesn't work)

    OpenVZ's upsides, for me:

    • it's usually cheaper

    The end result is that for ordinary things I'm happy to use OpenVZ, but if there's something out of the ordinary I'll use Xen or KVM (with a slight preference for KVM, because pygrub seems particularly brittle when it's used and because I like having VNC).

  • jcalebjcaleb Member
    edited August 2012

    @lbft said: unless it's vswap

    same memory consumption when running java for me. i.e. .18 and .32

  • Ash_HawkridgeAsh_Hawkridge Member
    edited August 2012

    If you want the power/functionality of a dedicated server, you go for KVM, simples. Im not saying OpenVZ doesn't have its benefits, for one faster reloads, a KVM re-install is not something i enjoy doing quite so often.

    Thanked by 1jar
  • I prefer xen/kvm but just okay with openvz. Depend for what it's used.

  • KVM has the most horrific, terrible I/O performance of any virtualization platform that I have ever seen.

  • corehostingcorehosting Member
    edited August 2012

    @vpsnodebox said: KVM has the most horrific, terrible I/O performance of any virtualization platform that I have ever seen.

    How horrific? Because i surely haven't seen that terrible results...
    With virtio - indeed - i get almost the same IO performances than on the host

  • @vpsnodebox said:

    KVM has the most horrific, terrible I/O performance of any virtualization platform that I have ever seen.

    Then your setting it up wrong. Sure, some operating systems perform slower with traditional DD tests, but those tests mean nothing anyway.

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