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Why XEN + SSD is not being used ?

Why XEN + SSD is not being used ?

darknessendsdarknessends Member
edited November 2012 in General

Hi,

I see a lot of OpenVZ - SSD offers and KVM - SSD offers, but XEN - SSD has become so rare. Is there a problem with XEN and SSD combination ?? Seems like normal XEN VPS are still available

Thanks

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Comments

  • XEN is becoming rare IMO.

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  • Yes, Xen is dying. SSD based offers are for new deployments, and there are almost no new Xen deployments.

  • @concerto49 said: XEN is becoming rare IMO.

    Especially seeing as the isolation and performance of KVM tend to be better now. And on the flip side OpenVz is much easier for some providers to set up, so you got Xen stuck in the middle (and Xen-PV doesn't seem like much of a point with KVM around).

    It might have something to do in part with KVM being natively supported in most of the recent kernels with new development going on.

    KBeezie - Insignificant little blog about Nginx, FreeBSD, fun stuff | PhoenixVPS - Managed Support Representative
  • @kbeezie said: OpenVz is much easier for some providers to set up, so you got Xen stuck in the middle (and Xen-PV doesn't seem like much of a point with KVM around).

    The reasons I see XEN for are:

    1. The myths. There are people out there saying only XEN = dedicated resources and are a lot faster. This isn't true.

    2. If you want to modify the kernel and need something Linux only. Xen PV that is still is faster than KVM, but this is rare.

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  • @prometeus may have some in future but overall XEN has been divorced even by RHEL, I read the article a few days ago

  • SpiritSpirit Administrator
    edited November 2012

    @concerto49 there's another myth "KVM + feeling of independency" with modifications, the feature everyone here praise and almost no one really need. I can't get rid of impression how LEB hosts are lately forced to go with KVM solely because they will easier sell it to LEB crowd because "its better" fame and nothing else. Your reasons "I see XEN for" are reasons of youngster who just lately found out virtualization while many other use it many many years without issue. XEN just work for me they way I want and need without pretending like I need (and pay for) some extra KVM features (ie. wasting a bit more time with initial setup, pretending how cool it is and then more or less same long term usability). But that's just my opinion :)

  • We are still using Xen and deploying it to new nodes with no plans to change from Xen, our latest node is using SSD storage.

  • @Spirit said: I can't get rid of impression how LEB hosts are lately forced to go with KVM solely because they will easier sell it to LEB crowd because "its better" fame and nothing else.

    The ONLY reason we're going with KVM is for BSD users and Windows users. Also those that need to modify the kernel in Linux. Not for said reasons you've mentioned anyway.

    However, customers are allowed to use it however they like. It is against our privacy policy to be questioning users for using it any way unless something against our TOS crops up.

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  • Yupps ! Onapp uses XEN primarily.

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  • kbeeziekbeezie Member
    edited November 2012

    @concerto49 said: If you want to modify the kernel and need something Linux only. Xen PV that is still is faster than KVM, but this is rare.

    Xen-PV is of course 'paravirtualization' (as opposed to hypervisor) similar to OpenVz but with the bootstraping making it possible to customize the kernel so of course it'll be faster. Course of my purposes the only time I ever had to modify the kernel was for FreeBSD which of course won't run on Xen-PV (unless there's a working version of it for a FreeBSD master that I don't know about), runs perfectly fine on KVM though especially with the VirtIO drivers compiled in.

    Far as your #1 point, back when it was mainly OpenVz vs Xen, you're right there was quite a few myths/hypes regarding Xen, such as saying it can't be oversold.

    KBeezie - Insignificant little blog about Nginx, FreeBSD, fun stuff | PhoenixVPS - Managed Support Representative
  • strictly speaking, xen can't be oversold in the sense of openvz. ie ram/disk (via lvm) and so on.

    That doesn't stop people from loading nodes down / not managing resource policies well. But it's a good bet you won't have the same potential for trouble as with oz.

    That said, since oz isn't really virtualization it's much, much faster for basic tasks without the overhead. If only 500 containers on a 32gb node weren't standard practice for oz hosts..

    Retired!

  • kbeeziekbeezie Member
    edited November 2012

    @unused said: strictly speaking, xen can't be oversold in the sense of openvz. ie ram/disk (via lvm) and so on.

    It can... just not as easily or to the same extent, it's been discussed before on LET.

    KBeezie - Insignificant little blog about Nginx, FreeBSD, fun stuff | PhoenixVPS - Managed Support Representative
  • @kbeezie - not really - not in the sense of "my os sees i have 4gb of ram and xxx disk space" that don't exist.

    Unless you are doing something crazy like forcing each vm to use a specific xen pv kernel you've created yourself.

    Retired!

  • kbeeziekbeezie Member
    edited November 2012

    @unused said: @kbeezie - not really - not in the sense of "my os sees i have 4gb of ram and xxx disk space" that don't exist. Unless you are doing something crazy like forcing each vm to use a specific xen pv kernel you've created yourself.

    Ever tried the Xen ballooning driver? (though you can usually detect it with /proc/xen/balloon )

    KBeezie - Insignificant little blog about Nginx, FreeBSD, fun stuff | PhoenixVPS - Managed Support Representative
  • @kbeezie - have you? It actually changes the amount of ram the vm sees. It doesn't fake the amount.

    Retired!

  • Xen isn't very popular, but it is used by a few major hosts like VPS.net which is OnApp based on Xen.

    - Ishaq
  • Unless you have a boatload of money sitting around and expect sales to be much higher for Xen over KVM, it makes sense to do KVM over Xen and couple that with OpenVZ. Xen isn't dying necessarily, but KVM is definitely on the rise and, one could argue, the future of "truly virtualized" VPS hosting. Certainly it doesn't make sense to do KVM and Xen (particularly when you're talking about an SSD-based node) unless, again, you have a boatload of money. I've considered doing a Xen node (just so we could cover all three markets), but I think it would do more harm than good to my sales. Sure, I'd sell some Xen boxes to the people who aren't really sure what KVM is or who just don't like it, but then I have to maintain stock on at least three different hardware configurations. When you spend a good chunk of money on these low RAM E3 nodes (as trend has become with many SSD VPS hosts), you have to pick your configurations wisely and keep a close eye on the wallet. I guess if you're unable to sell KVM at a reasonable rate, then try Xen. But most people who, for whatever reason, don't want OpenVZ are able to recognize that KVM is the Xen alternative.

    I'm betting at least one host here will realize there is a temporary potential niche in the Xen SSD VPS market and try to grab it. But for those who already sell KVM, it doesn't make sense. And for those who want to get into the market, KVM seems to just be a better option.

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  • Also, welcome to LET :)

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  • Simple cause SSD space is oversold and with Xen this is hard or not possible. At least not in the LEB price ranges.

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  • AnthonySmithAnthonySmith Member
    edited November 2012

    As someone with a fair bit of experience in XEN, I have to agree that KVM is the way things are heading, its not too hard to migrate from XEN to KVM either which is nice, not so simple to convert from OVZ to another type.

    Xen can absolutely be oversold, but not without it being completely obvious to the end user, there is a reason XEN and KVM are more expensive than OVZ and everyone knows why :)

    XEN + SSD, yup considered it many times, but if my niche was SSD then I would simply move on to KVM.

    As it stands now with RHEL 6 and the 3.6.x kernels it is more than possible to do Xen, KVM and OVZ from the same node, that will be the future IMO.

    EDIT: Always worth a mention that in a fair fight an OpenVZ VPS will usually out perform XEN or KVM in benchmarks... however the fight is not usually a fair one :) it is also worth noting that the OpenVZ kernels are lagging behind a bit and that extra boost you get by running XEN on a 3.6.x kernel is normally enough to take the edge.



  • KVM can be oversold ???

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  • @qhoster said: Simple cause SSD space is oversold and with Xen this is hard or not possible. At least not in the LEB price ranges.

    KVM is in the same boat, yet there are several SSD KVM providers.

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  • @kbeezie said: Course of my purposes the only time I ever had to modify the kernel was for FreeBSD which of course won't run on Xen-PV (unless there's a working version of it for a FreeBSD master that I don't know about)

    Amazon aws use Xen and they support freebsd.

    ...............

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