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Performance Evaluation of Xen Vs. OpenVZ

Posted by ryuzaki0 on from the price-to-pay dept.

An anonymous reader writes "Compared to an operating-system-level virtualization technology like OpenVZ, Xen — a hypervisor-level virtualization technology that allows multiple operating systems to be run with and without para-virtualization — trades off performance for much better isolation and security. OpenVZ's performance advantage due to running virtual containers in a single operating system kernel can be significant. A performance evaluation study (PDF) done by researchers at the University of Michigan and HP labs provides insight into how big a performance penalty Zen pays and what causes the overheads (primarily L2 cache misses)." From the report: "We compare both technologies with a base system in terms of application performance, resource consumption, scalability, low-level system metrics like cache misses and virtualization-specific metrics like Domain-0 consumption in Xen. Our experiments indicate that the average response time can increase by over 400% in Xen and only a modest 100% in OpenVZ as the number of application instances grows from one to four... A similar trend is observed in CPU consumptions of virtual containers."

116 comments

  1. Better known as Virtuzzo by Anarchysoft · · Score: 0

    Which I'm sure is feeling the heat from Xen.

    --
    Hax-fu?
    1. Re:Better known as Virtuzzo by Anonymous Coward · · Score: 0

      Haha, I had the last researcher listed, Kang Shin as a professor. He was seriously the worst professor I have ever had. He didn't even show up for my groups final presentation!

  2. Stop the press by general_boy · · Score: 3, Insightful

    [Xen]... "trades off performance for much better isolation and security."

    No kidding, that's why I use it! Xen's performance ain't so bad. Show me a better performing virtualization solution that matches or bests Xen's isolation security - then we'll talk.

    1. Re:Stop the press by vrmlguy · · Score: 1

      VMware? (Hey, you didn't say "free", although VMware Player and VMware Server are free-as-in-beer.)

      --
      Nothing for 6-digit uids?
    2. Re:Stop the press by jambarama · · Score: 4, Insightful

      Yeah but Xen is still a royal PITA to get running. KVM wasn't bad, and VMWare was pretty easy. I haven't even seen OpenVZ. Of the three I've tried, the ease of use was highly correlated to the product maturity. All three work, but IMHO VMWare is so far ahead it will take some time for Xen to be considered out of the hobbyist market and in the commercial one. I'm sure it'll get there, but to do what? Be a faster VMWare?

      So to sum, we've got OpenVZ, Virtualbox, KVM/Qemu, Xen, VMWare, Virtual Iron, and Virtuozzo. With so much virtualization software, I personally think performance takes a back seat to functionality (sure OpenVZ is fast, cool, what will it do for me that VMWare or Xen won't?). Is there really that much space in the virtualization landscape?

    3. Re:Stop the press by wertarbyte · · Score: 2, Interesting

      Yeah but Xen is still a royal PITA to get running.
      apt-get install xen-linux-system-2.6.18-4-xen-686 xen-create-image --hostname ........ done. Looks quite easy to me.
      --
      Life is just nature's way of keeping meat fresh.
    4. Re:Stop the press by Xouba · · Score: 4, Interesting

      Yeah but Xen is still a royal PITA to get running. KVM wasn't bad, and VMWare was pretty easy. I haven't even seen OpenVZ.

      Yes, Xen is harder to install. But to compare it with KVM ... did you try to use them? KVM (at least, last time I tried -- which was only a couple weeks ago) is still in development, and the performance is so low compared to Xen that it's not even funny.

      On the other hand, VMware is very nice, specially the free Server edition, and it's really easy to use. But even so, performance is better in Xen. Check this. Paravirtualization needs modified guests, but the outcome is so good that VMware is trying paravirtualization too.

      VMWare is so far ahead it will take some time for Xen to be considered out of the hobbyist market and in the commercial one

      What do you think is needed for Xen to be considered apt for commercial use? Remember that Xen can use unmodified guests if the hardware supports VTX/SVM instructions, which means that it can run Windows. Pretty front-ends? Xensource (which is slashdotted now, I guess, because it times out from here) offers one, and you also have Enomalism.

      Besides, by what Wikipedia says about OpenVZ, it seems to be more a solution like jails, because it uses the same kernel for both the host and the guest systems. The phrase "glorified chroot" comes to mind, though I'm aware that it's more than that (just adding it for the sake of trolling, I guess :-)). Xen, VMware and QEMU/KVM are, on the other hand, real virtualization solutions, where all the virtual system runs completely isolated.

      I wouldn't recommend Xen for home use (VMware Server is a better and easier option, IMHO), but saying that it's not ready and comparing it to QEMU/KVM is almost a joke.
      --
      My weblog in spanish
    5. Re:Stop the press by jaseuk · · Score: 3, Informative

      Virtuozzo/OpenVZ and VMWare have strengths in completely different areas.

      VMWARE is an excellent DR/BC solution due to complete virtual machine portability. However consolidation ratios (8:1 maybe) and performance are not that great, for consolidation you've probably only saved a few Us, but you have not really helped reduce the support burden, you'll still need lots of middleware / server management software to manage your estate. To actually get the most out of the DR/BC solution you also need an FC SAN and the complete Virtual Centre suite. If you've that kind of money to throw around then clearly you are in it for BC/DR purposes and VMWare is the right option. At this level you don't care if your consolidation ratios are 1:0.9 or worse.

      Virtuozzo/VZ on the other hand wins hands down for consolidation and management; you can easily fit 20-30 or more VPSes on a single server; and whatever the consolidation ratio the responsiveness will always be better than the same server under VMWare. However there are some drawbacks, Virtuozzo doesn't give you complete portability; you can only host Windows 2003 guest servers on a Windows 2003 hardware node for instance and you are unable to install device drivers. Adding a new VPS takes about as long and uses about as much resource as creating a new user on a system.

      I use both solutions; each definitely have their own place and couldn't be more different in their relative strengths.

      Jason

    6. Re:Stop the press by ovz_kir · · Score: 1

      Let me answer this way: Show me a single exploitable security hole in OpenVZ, or the way for a VE to do a Denial-of-Service for other VEs (i.e. the case of improper isolation) -- when we'll talk.

      --
      -- Kir Kolyshkin, OpenVZ project leader.
    7. Re:Stop the press by birder · · Score: 1

      I'm running several VMware ESX servers (4 CPU Opteron) with 15-20 VMs each and they're not even loaded up yet. I even have a ancient 4CPU Dell box running 16 VM's smoothly. Certain applications aren't VM friendly but 90% of them are and it is a great savings in power and space. VMotion is awsome as well not just for DR but for regular maintenance. When you have 15+ servers running on one box, it's hard to schedule ESX downtime to make everyone happy. VMotion solves this for us.

    8. Re:Stop the press by jaseuk · · Score: 2, Informative

      VMWARE consolidation tends to be limited by your overall system RAM. I can only assume that you are making very small RAM allocations (128M-192M?) or you have a large amount of physical RAM available (12-16GB?)

      Jason.

    9. Re:Stop the press by mikehoskins · · Score: 1

      As somebody that has used OpenVZ, VMware (several flavors, since the early beta days), QEMU, Bochs, Linux-VServer, and others, I like OpenVZ (and VMware Server but for totally different reasons). I looked at Xen and decided that I would grow old setting it up, so I abandoned that effort, for now.

      OpenVZ is easy to setup (once you get the kernel and packages setup, which is a breeze in Debian 3.1 and 4.0). It runs ridiculously fast, it consumes little memory, and takes little disk space (which can be further enhanced using hard links). Besides that, everything is fully scriptable. I also only have to maintain a single kernel (on the host).

      By reducing isolation (jails/containers vs. virtualization), the host machine can directly copy files into and out of guests, but the guests can't directly see each other (you can through ssh, for instance).

      I also like the fact that on the host machine, using ps -ef (or ps aux) gives you information on ALL processes, whether host or guest. The tty column shows you which machine owns a process.

      Since it's a shared kernel and uses shared memory, resource utilization is superior. If a guest isn't doing anything, it really isn't doing anything at all, unlike the virtualizers (except the up-and-coming KVM). The virtualized machines, for instance, keep running the "do nothing loop" when the OS is idle. (I believe that VMware Tools is supposed to help a bit in this regard). And, if processes aren't running or disk space isn't being used, then, unlike VMware, resources aren't being consumed.

      This is basically a way to run multiple guest Linuxes under a host, not a full virtualization environment, so there are trade-offs. I think that for running multiple Linux servers (as opposed to desktop apps), OpenVZ/Virtuozzo is an ideal solution.

      Since I'm running a smallish server at home, I've found that OpenVZ is the best way to run so many Linux guests at once.

      I will have to say that I have not tried UML because of performance. I can't try KVM since I don't have the correct AMD processors.

      I was also initially impressed by Linux-VServer but got stuck, somewhere, but I cannot remember where. I found that OpenVZ seemed to be easier and more powerful than Linux-VServer, its virtualization cousin.

      Here's a decent comparison of the kinds of VM's available for Linux:
          http://www-128.ibm.com/developerworks/linux/librar y/l-linuxvirt/?ca=dgr-lnxw01Virtual-Linux

      I really like OpenVZ and will be glad to put in a plug for it. Try howtoforge.com for some great help on setting up....

    10. Re:Stop the press by Zonk+(troll) · · Score: 1

      Yeah but Xen is still a royal PITA to get running. If you think that Xen is a "royal PITA" to get running, then how do you manage to work with a server? There is a slight learning curve, but after that it's extremely easy to deal with. Much like most Unix things. The massive performance benefit that Xen gives over VMWare Server (the only one I use) is well worth the hour it takes to learn the basics.

      Now, if you're virtualizing a desktop system, VMWare rocks. I use it daily for this. But after using both in production, Xen clearly has a significant performance advantage. Note, the performance is VMWare ESX server is supposed to be much better that VMware Server or Workstation. I don't have access to it, though.

      Here is the tutorial I used to get started. Really, it will only take about an hour to do it. From there you can begin learning the more advanced features, but that will give you enough information to be able to build VMs. I started with that, then moved to using Debian Etch as the host (it provides packages for Xen kernels and utils), and run several RHEL4/5 VMs, Debian Etch VMs, and Ubuntu Dapper VMs. It's very easy to do once you learn the basics. IMHO, it's easier to deal with than VMWare Server once you get the hang of it.

      If you're using Debian Etch, or Ubuntu Edgy or Feisty kernels and tools are available. Also install the libc6-xen package so you don't have to do what the tutorials say about /lib/tls. FC6 and RHEL5/CentOS5 has everything available and can be done at install time. They also have tools for graphically creating and managing Xen.

      Also, if you still fine none of this acceptable you can always pay for it. If you pay for it, you get support from XenSource and additional tools that make things easier. If you're going to be complaining about how "VMWare is so far ahead it will take some time for Xen to be considered out of the hobbyist market and in the commercial one", you should at least be comparing the commercial Xen tools to VMWare.
      --
      "The Federal Reserve is a fraudulent system."--Lew Rockwell
      End The FED. -
    11. Re:Stop the press by ppadala · · Score: 1

      > No kidding, that's why I use it! Xen's performance ain't so bad.
      > Show me a better performing virtualization solution that matches or bests Xen's isolation security - then we'll talk.

      KVM ? Though it is in early stages of development, in theory, it may be able to run faster than Xen. It's goals, however are different from that of Xen's

    12. Re:Stop the press by Ryan+Amos · · Score: 1

      I'll second this... Also, responsiveness starts to severely bog down when you have 8-10 VM instances on a box; I use it for testing AJAX web applications and we really can't rely on it for speed because the latency gets pretty bad at that level. I've used Virtuozzo's commercial product in the past, and you can indeed cram ridiculous numbers of VMs per box. We had modest Dell rackmount servers hosting 80-150 VMs and response times were still decent. The migration tools available on their commercial product are also great.

    13. Re:Stop the press by stevey · · Score: 1

      Nice to see you pimping xen-tools :)

    14. Re:Stop the press by flydpnkrtn · · Score: 1

      OK what you're missing here is that there are two sides of virtualization (well technically there are more but we'll go with 2):

      OS-based virtualization, which is done by OpenVZ, is based on "Virtual Environments" that all run under one kernel. It's kinda sorta like running different servers in their own "chroot jail", but with their own virtual interfaces, their own quotas, etc. etc. Generally because you're not semi-emulating hardware paravirtualization is faster

      Para-virtualization, which is done by Xen, KVM and VMware, essentially runs "emulators" (domUs) inside the host server (the dom0). The performance of using this strategy is helped out by virtualiation-specific processor extensions, hence the "para-" prefix. As other posts have pointed out, this approach is slower and uses more resources, but provides a "thicker partition" between the domUs.

      --
      Here's to the crazy ones
    15. Re:Stop the press by MikeBabcock · · Score: 1

      The FC6 Xen configuration was downright easy. Reboot into Xen kernel, run virt-manager, type in the URL for the install image, pick a virtual hard drive file/partition/lv, specify an amount of ram and number of CPUs and click finish.

      Repeat.

      Granted, I only used it for installing other FC6 images, but it was very simple.

      --
      - Michael T. Babcock (Yes, I blog)
    16. Re:Stop the press by stan_freedom · · Score: 1

      it will take some time for Xen to be considered out of the hobbyist market If you consider Amazon to be a hobbyist... Amazon launches Xen-powered virtual datacenter on demand or Amazon Elastic Compute Cloud (Amazon EC2)
    17. Re:Stop the press by Anonymous Coward · · Score: 0

      Look at Xandros Server 2.0 released last week: they work on top of Xen and it's very easy.

    18. Re:Stop the press by myowntrueself · · Score: 1

      xen-create-image --hostname ........ done. Looks quite easy to me.

      Now, you see, I've actually used xen-tools and I notice that you've cunningly left out the part where you edit /etc/xen-tools/xen-tools.conf

      because what you get when you *don't* edit that config file to suit is this (for example):

      The kernel image we're trying to use does not exist.
      The image is - /boot/vmlinuz-2.6.16-2-xen-686
      Aborting


      ie the default config file for the current version of xen-tools points to the wrong kernel. And thats just for starters; in order to actually *use* xen-tools (instead of just showing off how 'easy' it is) you have to make quite a few changes to that config file.

      Not that setting up Xen would be a challenge for any competent Linux sysadmin though. Especially not with xen-tools. But you *are* being disengenuous.

      --
      In the free world the media isn't government run; the government is media run.
    19. Re:Stop the press by drsmithy · · Score: 1

      If you think that Xen is a "royal PITA" to get running, then how do you manage to work with a server?

      Most likely, he's trying to do non-trivial things with Xen. Stuff like bridges to multiple vlans, interface bonding, multiple drives, and the like.

      Xen *sucks* from an administrative perspective if your environment is anything remotely complicated. VMWare has nothing to fear.

      There is a slight learning curve, but after that it's extremely easy to deal with. Much like most Unix things. The massive performance benefit that Xen gives over VMWare Server (the only one I use) is well worth the hour it takes to learn the basics.

      It takes a lot more than an hour to get Xen up and running in a non-trivial configuration. The management advantages of VMWare easily make it a better choice than Xen. Stupid amounts of computing power is dirt cheap these days, while people time is only getting more expensive.

    20. Re:Stop the press by drsmithy · · Score: 1

      Looks quite easy to me.

      That's because you're not doing anything interesting.

      Try working with multiple vlans, bonded interfaces, multiple drives in VMs, SANs, etc, then come back.

    21. Re:Stop the press by Anonymous Coward · · Score: 0

      If your distro of choice doesn't package Xen nicely for you, and you're not patient enough to roll your own Xen from the source, here's what you need: Xen Express. This is the easy-to-use version you're looking for.

    22. Re:Stop the press by WuphonsReach · · Score: 1

      I never had an issue with multiple drives in Xen.

      What drives me up the wall at the moment is bonded interfaces. The Xen scripts flat out suck for doing any sort of ethernet bonding in domain0.

      --
      Wolde you bothe eate your cake, and have your cake?
    23. Re:Stop the press by WuphonsReach · · Score: 1

      The bigger issue with VMWare is licensing costs.

      Unless you're spending $20k-$50k per server on hardware, VMWare pricing will seem very expensive (in the $3-$4k range per server is what I was quoted a few months ago). For smaller shops that have a few $6k-$10k servers and a small SAN, the VMWare costs make it a very hard sell (almost better to order another server).

      --
      Wolde you bothe eate your cake, and have your cake?
    24. Re:Stop the press by Anonymous Coward · · Score: 0

      Right. By "running" I think he meant "get working" not "have installed". We can all apt-get or yum, but lets be honest, Xen doesn't work right after an apt-get. It takes a bit of "tweaking", shall we say.

  3. "can increase" by Gothmolly · · Score: 0

    Xen's benchmarks vs. native, VM and UML are pretty decent. Not sure what cleverly crafted scenarios they're using here.

    --
    I want to delete my account but Slashdot doesn't allow it.
    1. Re:"can increase" by ppadala · · Score: 1

      > Xen's benchmarks vs. native, VM and UML are pretty decent. Not sure what cleverly crafted scenarios they're using here.

      Xen for that matter any virtualization will run CPU intensive applications very well and close to native. If it doesn't, there is some thing really wrong. The problem happens in I/O intensive applications. It's not our (I am the primary author of the report) goal to find clever scenarios to find where Xen is worse. These scenarios are real and use complex multi-tier setups. These scenarios are very commonly used in server consolidation and we wanted to evaluate how Xen and OpenVZ compare. More importantly, from a research perspective, what exactly causes these trade-offs ?

      P.S. These are my personal opinions and don't reflect that of HP.

  4. KVM by QueePWNzor · · Score: 2, Insightful

    Kernel VM is based off QEMU -- but doesn't Xen have a similar hypervised Linux kernel. (I personally thought that may be why KVM was created -- to be a better Xen.) As I'll eventually upgrade to a Linux distro with KVM, I wonder if there are similarities in them -- or preferably if KVM could be fully tested and compared with these results.

    1. Re:KVM by Anonymous Coward · · Score: 0

      Dunno, I've tried Qemu WITH acceleration enabled (i.e. making in run in virtualization mode instead of interpretation mode), but it was so goddamn slow. VMWare was maybe four TIMES faster, at least for real-life usage (like installing Fedora).

      Only the VMWare Player UI sucks, so I switched to VirtualBox, which works fine.

      Also, the QEmu Kernel acceleration (which also lets kernel code run virtualized) always crashed the guest kernel. Well, here's just hoping they improved things. Having virtualization right inside the Linux kernel is a nice thing.

  5. Looks like analyst talk by fred911 · · Score: 2, Funny

    " hypervisor-level virtualization technology that allows multiple operating systems to be run with and without para-virtualization "

      I don't know about you but it still makes my eyes hurt!

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    09 F9 11 02 9D 74 E3 5B - D8 41 56 C5 63 56 88 C0 45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B2
  6. Oblig. Nonsensical reference by jd · · Score: 5, Funny
    how big a performance penalty Zen pays

    Zen's performance issues were fixed by Avon, under Orac's guidance.

    --
    It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
    1. Re:Oblig. Nonsensical reference by LurkerXXX · · Score: 1

      But what does it matter? The 7 are dead. :(

    2. Re:Oblig. Nonsensical reference by fred911 · · Score: 0, Offtopic

      Are you sure you didn't mean..

      "'Twas brillig, and the slithy tovesDid gyre and gimble in the wabe:All mimsy were the borogoves,And the mome raths outgrabe".

      Sorry... it was the 1st thing I thought of when I read the article

      --
      09 F9 11 02 9D 74 E3 5B - D8 41 56 C5 63 56 88 C0 45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B2
    3. Re:Oblig. Nonsensical reference by Anonymous Coward · · Score: 0
      That's what you think.

      Avon _is_ still alive. And he's in control of the whole shebang.

    4. Re:Oblig. Nonsensical reference by njh · · Score: 1

      Affirmative!

    5. Re:Oblig. Nonsensical reference by Anonymous Coward · · Score: 0

      Confirmed! (Get your quotes straight, mate :-)

    6. Re:Oblig. Nonsensical reference by njh · · Score: 1

      So right you are, affirmative is k9.

  7. Re:Looks like analyst talk by interiot · · Score: 3, Informative

    Hypervisor — the software that makes the virtualization happen... sometimes means virtualization that runs on bare-metal, rather than under a host OS.

    Paravirtualization — I think this just refers to the cases where the guest OS is modified/recompiled to run work without needing to run in Ring 0, and instead changes those to be explicit calls to the virtualization software.

    So translated, I think that means "virtualization software that runs on bare-metal, both using unmodified guest OS's, and modified guest OS's."

  8. vserver + unionfs by a1mint · · Score: 1, Informative

    I use vserver in combination with unionfs, which just rocks.

    I can add and remove (semi) virtual machine at will. Each VM feels barely heavier than just an ordinary process.

    I take my normal mount points, and make it the read-only layer. I then add a writable layer on top of that and that's it. I've also created some handy scripts that'll let me manage, add, remove, start, stop, etc, VM's.

  9. Re:Looks like analyst talk by Jartan · · Score: 2, Insightful

    From reading the article on hypervisor it still seems ambiguous. It implies that a hypervisor is not exactly a VM but the actual detailed description makes it out to be a VM. Others seem to imply it means the VM is running as an OS basically.

    From everything I can see though the word is useless and it amounts to the equivalent of computer scientists being fussy. VM or VM OS are better choices.

  10. And OpenVZ works with FreeBSD? Windows? by Anonymous Coward · · Score: 1, Interesting

    OpenVZ works with FreeBSD?

    Does anyone have links to show the support?

  11. Both are good. by Blackknight · · Score: 4, Informative

    As somebody that actually has experience setting up and running virtualized systems (I work for a web hosting company) let me add my two cents here.

    OpenVZ is ok if all of your child environments run the same OS and you don't care about them stealing each other's resources. We constantly have problems with customers overloading their VPS and causing problems with the other environments, this doesn't happen with Xen. I've fork bombed child environments and caused the load to spike to over 700 until it crashed, dom0 and the rest of my domUs just kept running like nothing was even happening.

    OpenVZ also wins if you want to oversell hardware, Xen doesn't have "burstable" memory like OpenVZ does. Personally I prefer Xen for the jailing that it does and you can also run multiple OSes at the same time. I have a server at work that's running CentOS, Windows 2003, Windows Longhorn, and Gentoo all at the same time, OpenVZ only lets you run Linux on Linux.

    1. Re:Both are good. by flydpnkrtn · · Score: 5, Informative

      When you sit down and do your homework, and don't oversell as you said, OpenVZ gets the job done. I was looking for a good way of virtualizing a new server we were moving to and I've gotta say I can't see myself ever NOT installing a server in either an OpenVZ VE or a Xen domU ever again.... with OpenVZ you can give one VE (almost) all the resources of the hardware its running on, and when that one server outgrows that hardware doing a vzdump or vzmigrate is sooo easy.

      The big difference between Xen and OpenVZ comes down to what openvz calls "privvmpages" - memory that is claimed by running processes but not actually used.

      The example here is this: two OpenVZ virtual environments (VE) can be set up on a server with, say, 1 gig of ram, with a gig of swap underneath it (So, RAM+Swap equals 2 gigs).

      Those two virtual environments can be "oversold" in the amount of privvmpages they're allowed to use, because processes ask for more memory than they _actually use_ all the time. So let's say we give those two VEs 1.5 gigs of privvmpages (total of 3 gigs - more than RAM+Swap), but we only give them each 500 megs of oomguarpages. (less than RAM+Swap).

      The thing that _should never_ go over RAM+Swap is oomguarpages (out of memory guaranteed pages) - pages of memory that are guaranteed (OpenVZ measures some of its resources in pages and some in megs).

      With Xen, on that server I just described you're locked in - there's no bursting, and there's no dynamic allocation going on. You give one domU 750 megs of ram and you give the other domU 750. That's it.

      --
      Here's to the crazy ones
    2. Re:Both are good. by passthecrackpipe · · Score: 2, Insightful

      I've gotta say I can't see myself ever NOT installing a server in either an OpenVZ VE or a Xen domU ever again

      Remind me to never EVER hire you to do any work for me. Ever heard of "the right tool for the job"? I am a huge fan of virtualisation, and have been using it for years, VMWare mostly, but lately more and more with Xen. Given that Xen simply does not yet play nice with most of the lower cost hardware, and has several significant shortcomings in real-life enterprise production environments (running against a multihomed SAN is a not-so-distant nightmare), Xen still has some work left to do. Anyhow, I'm a huge fan of virtualisation, but there are plenty of workloads that simply do not work well virtualised, irrespective of the VM flavour du-jour you are using.

      Saying you will only ever use virtualised workloads is stupid, and unprofessional. -and no, the fact that you got [oracle,mysql,postgresql] to run in a VM does not mean its going to be anywhere near decent performance.

      --
      People who think they know everything are a great annoyance to those of us who do.
    3. Re:Both are good. by ovz_kir · · Score: 1

      OpenVZ is ok if all of your child environments run the same OS and you don't care about them stealing each other's resources.
      OpenVZ isolates VEs from each other pretty good, unless you misconfigure it. The problem here is you can't configure the system properly (i.e. you oversell way too much). See this article to get the details on how to configure your system in a proper manner.
      --
      -- Kir Kolyshkin, OpenVZ project leader.
    4. Re:Both are good. by Tony+Hoyle · · Score: 1

      The worst virtualisation experience I ever had was on Virtuozzo. I was with a host that was running UML. Everything worked fine, no issues with it.

      Logged in one day and nothing worked. The host had changed to Virtuozzo. They tried to sell us on the advantages 'look it has a cool web based frontend' they said. It sucked. It had lower bandwidth, lower memory available and was as slow as molasses (like the load average never went below 4 on an idle system running nothing else).

      We coped with that for about 3 hours, ditched them and went to a xen host which has been 100% fine ever since. It will be a cold day in hell before virtuozzo ever gets another chance around here.

    5. Re:Both are good. by Cyberax · · Score: 1

      OpenVZ allows you to set CPU and RAM quotas, and in my experience they work just fine.

      OpenVZ also has a very distinct advantage - all processes in guest VEs are visible to the tools on the main host.

    6. Re:Both are good. by Anonymous Coward · · Score: 0

      When you sit down and do your homework, and don't oversell as you said, OpenVZ gets the job done.

      My homework says it doesn't work with FreeBSD. So it really doesn't get the job done.

    7. Re:Both are good. by ovz_kir · · Score: 1

      See what the problem is -- a provider can oversell, and they oversell, sometimes way too aggressively. As long as you are not the owner of a physical server, you can not do anything about it but buy from more sane provider. This has nothing to do with the technology itself. As for technology, see the HP labs evaluation.

      --
      -- Kir Kolyshkin, OpenVZ project leader.
    8. Re:Both are good. by flydpnkrtn · · Score: 1

      Saying you will only ever use virtualised workloads is stupid, and unprofessional. -and no, the fact that you got [oracle,mysql,postgresql] to run in a VM does not mean its going to be anywhere near decent performance.

      I wasn't specifically saying I would do the virtualization with Xen... if it was specifically a Linux server I would most definitely run it in an OpenVZ VE. You seem to think "virtualization" automatically means paravirtualization, not OS-based virtualization.

      What I meant was that even if the server was only going to host one OS (one copy of Apache, one copy of mySQL, etc. etc.), I'd still setup OpenVZ on the node side and setup the OS inside a VE on that server... this gives you a huge amount of portability.

      For backups, I can take a snapshot of the current VE without even interrupting the services running in that VE (if the node is running on LVM), or only minimal downtime (I'm talking 3-5 minutes) if its not.

      If the server's load is getting too high because the site's getting Slashdotted I can simply snapshot my VE and move it over to a beefier server with more RAM/CPU that's running OpenVZ. No rsync, no reinstall. No fuss, no muss

      I can have the node be Debian 3.1 and run in the VEs Gentoo, CentOS, Fedora, Debian, etc. etc.

      I realize the performance hit Xen-based virtualization imposes. As the article points out OpenVZ-based virtualization doesn't carry that performance hit. I'd even still consider running e.g. a Windows server in a Xen domU because of the portability that would give me as well. Of course anything would be tested with an appropriate load before putting it into production... and I'd NEVER consider running two disk intensive VEs or domUs side by side (e.g. two virtualized database servers side by side)

      --
      Here's to the crazy ones
    9. Re:Both are good. by passthecrackpipe · · Score: 1

      You don't have to sell me on the benefits of virtualisation. I'm all for it. None of the benefits you list are exclusive to virtualisation. If on the fly snapshotting is a key business requirement for me, I will pick the right tool for the job. Depending on the customer (well, mine anyway) that will usually be a more specialised storage device. I can go on and on, but the bottom line, the attitude that you will "NEVER" use anything other then virtualisation is unsound

      --
      People who think they know everything are a great annoyance to those of us who do.
  12. Yes, but ... by Anonymous Coward · · Score: 4, Funny

    Does it run multiple instances of Linux?

    1. Re:Yes, but ... by TommydCat · · Score: 3, Funny

      Perhaps you can harness all of those multiple instances in a beowolf cluster.... Hmmmm!

      --
      This comment does not necessarily represent the views and opinions of the author.
  13. Re:Looks like analyst talk by Anonymous Coward · · Score: 0

    The hypervisor is essentially a light-weight OS, on which the VMs are running. The hypervisor manages the underlying hardware, and provides virtualized access to the hardware, for the VMs.

  14. And... by coyote4til7 · · Score: 5, Insightful

    Nothing like a virtualization comparison that ignores the 800 guerilla that is VMWare. How do the learning curves, performance and security of these products compare with VMWare? Why should someone who is satisfied with VMWare consider other alternatives?

    --

    the clock on the wall says 4 til 7
    1. Re:And... by myowntrueself · · Score: 2, Interesting

      Why should someone who is satisfied with VMWare consider other alternatives?

      How should someone who is satisfied witn VMWare decide whether an alternative would be an improvement? When the license terms for VMWare prohibit any benchmarking its kind of hard to make a decision.

      --
      In the free world the media isn't government run; the government is media run.
    2. Re:And... by coyote4til7 · · Score: 4, Insightful

      Good point.

      Do I get a Karma bonus for conceding someone's point? ;-)

      --

      the clock on the wall says 4 til 7
    3. Re:And... by Chirs · · Score: 3, Informative


      This is a bit out of date, but here is some comparison between Xen, User Mode Linux, and Vmware 3.2 (which is the most recent version that allows publication of benchmarks).

      http://www.cl.cam.ac.uk/research/srg/netos/xen/per formance.html

      Xen is always faster than Vmware, with the exact amount varying depending on the specific load. They've all improved since then, of course.

    4. Re:And... by soulhuntre · · Score: 1

      Microsoft's Virtual Server is a free product now and does a really, really good job.

      --
      --> Fight tyranny and repression.... read /. at -1!
    5. Re:And... by Anonymous Coward · · Score: 1, Interesting

      (which is the most recent version that allows publication of benchmarks). Really ? Then what is this:

      http://blogs.xensource.com/rogerk/wp-content/uploa ds/2007/03/hypervisor_performance_comparison_1_0_5 _with_esx-data.pdf

      Xensource themselves claim "xensource performance as well as vmware" in thier white paper which shows VMware to be slower only in specjbb and xensource is slower in some areas. And this is the highly optimized commercial version (not free, thousand something per core - still cheaper than vmware though)

    6. Re:And... by Anonymous Coward · · Score: 0
      esx eula

      You may use the Software to conduct internal performance testing and benchmarking studies, the results of which you (and not unauthorized third parties) may publish or publicly disseminate; provided that VMware has reviewed and approved of the methodology, assumptions and other parameters of the study. Please contact VMware to request such review.
      So it should be possible to benchmark esx in theory anyway. I would like to read such a benchmark if someone finds one.
    7. Re:And... by Bert64 · · Score: 1

      Providing that vmware has reviewed and approved of the methodology...
      Meaning that, any methodology which favours anything other than vmware will not be approved. In this case, i think the lack of available benchmarks says more.

      --
      http://spamdecoy.net - free throwaway anonymous email - avoid spam!
    8. Re:And... by Anonymous Coward · · Score: 0

      We started out with Connectix Virtual PC 5.1 and moved on to a Virtual PC server environment for our initial foray into virtualisation, and we quickly regretted it. The management console was a pain in the backside and it simply didn't scale.

      We've now switched to VMWare ESX 3 and are so happy with it we're planing on adding a second VMWare server to handle the planned load.

      In a similiar vain I still find VMWare Player preferable to Virtual PC 2007. The only thing Virtual PC has over VMWare is the ability to create new VMs, but it's not hard to find some very good VMX Builders.

      For what it's worth, as a developer I've also found that Virtual PCs hardware emulation is pretty flaky, especially compared to products such as VMWare and Qemu (Although in fairness, still much better than VirtualBox). As a user, you probably don't care so much.

    9. Re:And... by ppadala · · Score: 1

      Nothing like a virtualization comparison that ignores the 800 guerilla that is VMWare. How do the learning curves, performance and security of these products compare with VMWare? Why should someone who is satisfied with VMWare consider other alternatives? We would gladly run the same kind of experiments on VMware, but VMware does not allow publishing results, unless they have a look at them first. They probably don't want unfavourable results to be published. As an academic, I really hate such restrictions and want to do an un-biased study.

      Pradeep (Primary author of the mentioned report)

  15. comparing apples to orange by Anonymous Coward · · Score: 0

    The article (yup, I've speed read TFA) defines Xen as a para-virtualization systems... Completely ignoring that since now years Xen also allows to do hardware-virtualization. Another posted also noted already that Xen's power lies in its ability to run different OSes.

    Btw I happen to run my Samba / NFS / CVS / SVN server on a Xen para-virtualized domU. For hardware-virtualization I tried Xen too and the open, free, version lacks good I/O drivers for Windows (slow network and slow disk).

    People want to Google on exactly "Which virtualization is right for you" and read infos from a knowledgable sysadmin (managing thousands of servers and virtual servers on a lot of various platforms and, no, it's not me) instead of an article performing micro-benchmarking of hypercalls to compare apples to oranges.

    1. Re:comparing apples to orange by ppadala · · Score: 1

      The article (yup, I've speed read TFA) defines Xen as a para-virtualization systems... Completely ignoring that since now years Xen also allows to do hardware-virtualization. Another posted also noted already that Xen's power lies in its ability to run different OSes.

      Btw I happen to run my Samba / NFS / CVS / SVN server on a Xen para-virtualized domU. For hardware-virtualization I tried Xen too and the open, free, version lacks good I/O drivers for Windows (slow network and slow disk). We very well know that Xen supports hardware-virtualization as well. As you pointed out, the performance is abysmal because Xen still uses IO emulation while using hardware virtualization.

      People want to Google on exactly "Which virtualization is right for you" and read infos from a knowledgable sysadmin (managing thousands of servers and virtual servers on a lot of various platforms and, no, it's not me) instead of an article performing micro-benchmarking of hypercalls to compare apples to oranges. These are NOT micro-benchmarks. Infact, I would call them macro benchmarks. A few server consolidation scenarios are setup and the performance of Xen and OpenVZ is compared. Then, we dug deeper to find out the reasons for the problems using Oprofile. It's not comparing orranges to apples, because both technologies are touted for server consolidation.

      There's no single virtualization technology that works for every one, as many have explained in earlier comments.

      Pradeep

  16. Xen vs VMware - personal experience by Anonymous Coward · · Score: 5, Informative

    Here are a few talking points based on my experiences with both Xen and VMWare (ESX Server & Workstation).

    1. Cost - no contest, xen wins hands down $0 vs $5000/cpu.
    2. Performance - xen wins noticably, i can get away with running 8 virtual machines with 1/4 the hardware that VMWare required for 6.
    3. Capabilities - VMware versions ESX GSX and up beat Xen in ease of use and flexibility, anything less and Xen wins. Xen does have a quicker live migration capability, but falls short on conencting external hardware to the virtual machine (something that is trivial in VMware).
    4. Stability - about even, maybe Xen. I've seen ESX crash once, and have never seen Xen crash.
    5. Ease of use - VMWare no question. Theres a learning curve to Xen and setting up new VM images is a pain. (which is disappearing) There are fantastic tools for VMware that will let you manage virtual machine creation and even migration from a physical box. (some of which can be used to feed xen too =))

    The bottom line. A Xen setup (using open source version) that can easily run 12 VMs costs about $2,000 on DIY hardware. A VMWare server/software combo to do the same? about $30,000. Assume an additional 40-80 hours of learning to get up to speed with Xen vs VMware.

    The comments above cover the open source / free version of Xen. I have no experience with the commercial Xen offerings.

    Personally i'm Xen biased due to cost.

    1. Re:Xen vs VMware - personal experience by eht · · Score: 1

      And I'm biased to VMWare for the exact same reason, I think someone may be underpaying you.

    2. Re:Xen vs VMware - personal experience by Anonymous Coward · · Score: 0

      Performance:

      Iam not sure why people think xen is so much faster than ESX. Xensource themselves claim "xensource performance as well as vmware" in thier white paper which shows VMware to be slower only in specjbb on linux (paravirt vs bt which is unfair comparision). In fact paravirt should be compared to the VMI.

      http://blogs.xensource.com/rogerk/wp-content/uploa ds/2007/03/hypervisor_performance_comparison_1_0_5 _with_esx-data.pdf

      BTW VMware does allow benchmarking as its aparent from the paper xensource put out.

    3. Re:Xen vs VMware - personal experience by Anonymous Coward · · Score: 0

      =)

      I own my own company.

    4. Re:Xen vs VMware - personal experience by Anonymous Coward · · Score: 0

      Good points. Also note that this comparision with highly optimized commercial xensource product ($750 perpetual per dual socket; $488 annual subscription per dual socket)

      The free xen performs worse than vmware! http://www.vmware.com/pdf/hypervisor_performance.p df

    5. Re:Xen vs VMware - personal experience by Xouba · · Score: 2, Insightful

      Personally i'm Xen biased due to cost.

      I agree. Just a little addition: besides, VMware licenses are even more important when you want to scale. Say you want to use two quad boxes for load balancing, running VMware in each: that's about 8 x 5000 = $40000 in licenses (or $35000 if the first CPU is for free; I'm using your prices, but I knew about a similar project where VMware was decided against due to licensing costs too). You can buy more hardware with that money and train all your staff to understand and use Xen.

      --
      My weblog in spanish
    6. Re:Xen vs VMware - personal experience by Anonymous Coward · · Score: 0

      Not to mention, it's showing VMware Workstation 3.2. WTF was that released? 1997? Try comparing it to ESX 3.

    7. Re:Xen vs VMware - personal experience by Bert64 · · Score: 1

      But that comparison is on vmware's site, and xen is much newer than vmware 3, infact vmware 4 if not 5 was available before xen.
      Why would vmware compare xen to an old version of vmware? That seems rather fishy... You'd think they would want to compare xen to their latest and greatest

      --
      http://spamdecoy.net - free throwaway anonymous email - avoid spam!
    8. Re:Xen vs VMware - personal experience by mbourgon · · Score: 1

      2. Performance - xen wins noticably, i can get away with running 8 virtual machines with 1/4 the hardware that VMWare required for 6.

      Tell me more, please. Looking at the Xen performance paper, it looks like Xen & VMWare are pretty close, performance-wise. The most they ever show is a 23% boost on a couple tests - nowhere near the "1/4 the hardware". Not trying to bait, but honestly curious.

      --
      "Sometimes a woman is a kind of religion, she can save your soul & set you free from all your sins" - Bad Examples
    9. Re:Xen vs VMware - personal experience by phish · · Score: 2, Insightful



      There's one item you didnt list, though it might be folded under capabilities or ease of use...

      Manageability is a key item for these types of setups. As people being to depend more and more on virtualization technologies (whatever those might be) and roll out virtualized production environments, you have to figure out how to monitor and manage them. This is one area where VMWare currently has the upper hand, as Xen's management API has not yet been stabilized.

      The reason this is important is because with all the hype surrounding virtualization, people seem to be focused on 'getting virtualized' (server consolidation being the primary driver) rather than the consequences (application capacity issues, constant live migrations to keep things healthy, etc.).

      Manageability is a key stepping stone into the enterprise. Xen's made great strides recently (both in the open source form and in the commercial form), but there's a ton of work left to do on that end to catch up to VMWare.

      -javier
      http://www.hyperic.com/

    10. Re:Xen vs VMware - personal experience by Thumper_SVX · · Score: 2, Insightful

      You missed the biggest point for a corporation; Support. No corporation looking at virtualization (and let's get real; almost all of them are) is going to use Xen OR OpenVZ at this point because there's no single point of contact for support, and no support contracts.

      Quite simply, a corporation is going to buy VMWare Virtual Infrastructure. So the performance isn't as good? So what? Throw hardware at it. It works.

      We have a significant investment in VMWare VI3 where I work, and it's great. We run it on high-end highly scalable enterprise hardware (IBM) and it almost never dies. We lose guests occasionally because of Windows problems, but so far we have never lost a host machine, and they never go down except when we need to maintain or upgrade them.

      Last week we had a CPU die in one of our highly redundant, highly scalable boxes. Apart from the alert thrown up in MOM we practically didn't even notice the glitch. VI3 kept plugging along until we could roll the guests off to another host on the SAN and we took the box out after lunch, replaced the CPU and it was back in production within an hour. The business units who use the guests never even noticed the outage.

      Note though that to a corporation, the license cost is trivial for the security that if we had a host failure (software, not hardware) then there's one number to call; EMC/VMWare. Trawling the Usenet and Google Searches don't cut it from a Corporate perspective. And let's face it, Corporations are the primary target market for virtualization, not the consumer (at least today).

      As an aside, consumer level virtualization will happen soon, but it will be transparent to the user. It's probably going to be more akin to OpenVZ's "uber sandboxes" than VMWare but it will definitely happen in my opinion.

    11. Re:Xen vs VMware - personal experience by Anonymous Coward · · Score: 0

      obviously you would not be the greatest manager..

      But if you have to spend more time on something that takes more tweaking to get started up than that costs money. Unless you have some type of slave labor at your hands, time costs money.

    12. Re:Xen vs VMware - personal experience by darrylo · · Score: 1

      Going off on a slight tangent, VMware Workstation (non-free, $$) is the only one that has a glimmer of (imperfect) DirectX support, although there are rumors about similar support in the forthcoming OS X version. This is important for home users (not enterprise or business users) that run windows to play real-time 3D games. ;-)

    13. Re:Xen vs VMware - personal experience by Macka · · Score: 1

      You missed the biggest point for a corporation; Support. No corporation looking at virtualization (and let's get real; almost all of them are) is going to use Xen OR OpenVZ at this point because there's no single point of contact for support, and no support contracts
      Um, what about Redhat and Novel (SuSE)? Redhat have restructured how they sell RHEL 5 based exclusively on how many Xen VMs you're allowed run. Their standard RHEL 5 Server allows you to run up to 4 guest VMs, where as RHEL 5 Advanced Platform allows an unlimited number of guest VMs and also includes the RHEL Cluster suite. If the guest VMs are RHEL then it's all included in the one cost, and of cause it's fully supported. There's no excuse for turning your back on Xen based on support.

      Last week we had a CPU die in one of our highly redundant, highly scalable boxes. Apart from the alert thrown up in MOM we practically didn't even notice the glitch. VI3 kept plugging along until we could roll the guests off to another host on the SAN and we took the box out after lunch, replaced the CPU and it was back in production within an hour. The business units who use the guests never even noticed the outage
      And that is the beauty of Live Migration; IMHO the single most compelling reason for choosing Xen or VMware over OpenVZ. The cost of change control in time and resources, and the down time to a business for essential maintenance can be astronomical in a corporation. The ability to do what you just described is a killer feature and more businesses will wake up to this over time.

    14. Re:Xen vs VMware - personal experience by Thumper_SVX · · Score: 1

      Um, what about Redhat and Novel (SuSE)? Redhat have restructured how they sell RHEL 5 based exclusively on how many Xen VMs you're allowed run. Their standard RHEL 5 Server allows you to run up to 4 guest VMs, where as RHEL 5 Advanced Platform allows an unlimited number of guest VMs and also includes the RHEL Cluster suite. If the guest VMs are RHEL then it's all included in the one cost, and of cause it's fully supported. There's no excuse for turning your back on Xen based on support. And who does one turn to when a bug is found in the code? One that is critical for your functionality?

      Don't underestimate this as a driving factor for corporations. We had this exact problem with the first release of VI3, and it was a show-stopper bug. We called EMC, and had a significant patch sent out to us within 48 hours which was subsequently rolled up into the next release. The problem corporations see with Xen and OpenVZ is that there are no programmers at the companies you mentioned actually coding this. If a bug comes up, the impression most corporations have is that you have to post to some bulletin board and wait until some "unemployed hippie coder" has time to see if he can create a patch.

      Don't slam me for that, that's not my impression. I know a lot of Open Source coders, and I know they're as or more professional than many of their corporate cousins... but that's the impression that's still prevalent in the board room. Novell has made some great strides in making open source more "acceptable" to the corporation, but many corporations I have worked with are somewhat afraid of Novell's financial position (stock, not cash in the bank) and thus feel that Novell is somewhat "untrustworthy". As for Red Hat... well, since they began as a Linux company they're viewed as a Linux company. The feeling in the boardroom is that Red Hat is riding on the coat tails of those same "hippie coders" and doesn't really have any stake in the success of Xen (I know that's false!).

      I personally haven't turned my back on Xen; I use it on my home Linux server. However, from a Corporate perspective VMWare is king, and their support is simple and easy to understand. Many corporate heads have never heard of Xen or OpenVZ and thus will not listen. Their opinion is usually Virtualization = VMWare, mostly because VMWare was there first with a good product. Even Microsoft have had incredible difficulty getting their virtualization solution accepted in corporations because their solution is considered an "also-ran" and therefore less mature. The only way Microsoft has managed to get as much traction as they have with Virtual Server is because they strongarm the corporations by saying "If you put a domain controller / exchange server etc. on a VMWare guest then we will not support you... but we will if you put it on Virtual Server." I've had that exact conversation with Microsoft.
    15. Re:Xen vs VMware - personal experience by Anonymous Coward · · Score: 0

      Actually the time was purely in the initial learning a year or so back. Now to add a new server it takes all of 15 minutes and that's because i havent spent the time to write a little script to automate that. We did at one point spend about 80 hours of work troubleshooting a VMWare issue that we couldn't get any info on (VMWare support didn't help either). That time did cost us alot of money.

  17. Other VM options.. by tji · · Score: 2, Informative

    Linux has a lot of great VM options. VMware is a great free (cost) option, and KVM has become a great option very quickly. OpenVZ and VServer are interesting light weight OS "jail" virtualizations. They each have pros and cons, depending on your requirements and apps being used.

    I'm setting up my "next generation" home linux server, and looking into the virtualization options for that. Probably a bigger factor than performance is the setup and manageability. I have found Xen to be pretty primitive compared to VMWare.. setup is a pain, documentation is spotty, and support is minimal. The one advantage of Xen is that you can (and often must) do everything with it from the command-line. The GUI tools are weak at best.

    I am now leaning towards using VMWare server. But, I still need to do some testing with KVM.. articles I have read about it sound very impressive. KVM paravirtualization performance is supposed to be excellent. But, I don't know about management.

    1. Re:Other VM options.. by cerberusss · · Score: 1

      I have found Xen to be pretty primitive compared to VMWare.. setup is a pain

      That's what I thought, too. Until I installed CentOS (*the* RedHat Advanced Server clone). Start virt-manager, click Create, click next-next-finish and voila, you have a window showing an installation.

      --
      8 of 13 people found this answer helpful. Did you?
  18. Lousy virtualization, Happy users... by MavEtJu · · Score: 2, Informative

    Go the FreeBSD way!

    Lousy virtualization, Happy users: FreeBSD's jail(2) facility
    Source: UKUUG
    Tags: ukuug, presentation, freebsd, jails, poul-henning kamp
    Slides (2.7 Mb)
    Lousy virtualization, Happy users: FreeBSD's jail(2) facility by Poul-Henning Kamp (phk@FreeBSD.org)

    --
    bash$ :(){ :|:&};:
  19. Re:And OpenVZ works with FreeBSD? Windows? by tres · · Score: 1


    OpenVZ and Virtuozzo rely upon Linux kernel modifications; in other words, no FreeBSD, no Windows.

    --
    Notes From Under *nix: blas.phemo.us
  20. Re:Looks like analyst talk by Tumbleweed · · Score: 1

    " hypervisor-level virtualization technology that allows multiple operating systems to be run with and without para-virtualization "

    > I don't know about you but it still makes my eyes hurt!

    Really, it's not that complex. The technology monitors all system calls, and makes a judgement call - if it's safe to let it through, it routes it through the EPS conduits. If it's not, it routes it through the GNDN tubes. As long as you don't overload the EPS taps, it's all good.

  21. It's not always about performance by cerberusss · · Score: 4, Informative

    It's not always about performance; Xen gets each their separate kernel. This means that special adjustments can be made for a virtual machine. Also, with Xen you could easily experiment with an upgraded kernel for the virtual machines, without rebooting the main (host) machine. Finally, I for myself like the fact that you have your 'own' kernel. It feels much more like a real machine. Especially with a bootloader like pygrub, which is employed in RedHat AS and CentOS, the kernel inside the virtual machine can even be upgraded by yum running inside the VM.

    Note that I'm not a Xen apologist, I'm not denying a performance hit here.

    --
    8 of 13 people found this answer helpful. Did you?
  22. Appples and oranges... by flyingfsck · · Score: 3, Interesting

    OpenVZ is somewhat like FreeBSD Jails. It provides some separation which makes it easier to manage multiple complex servers. For example, it makes sense to run a web server and mail server in two separate virtual machines, since it keeps the configuration independent.

    Xen, is like VmWare or Qemu and provides an independent virtual machine for each system. These systems can be anything at all: Windows, Linux, BSD, whatever.

    Performance wise, OpenVZ is bound to win, because it is a different solution to a different problem.

    --
    Excuse me, but please get off my Pennisetum Clandestinum, eh!
  23. isolation and ease of use by dropadrop · · Score: 1

    As long as the performance is not bad, I'll take isolation and ease of use over an edge in performance any day. If performance is not good enough, I'll buy a faster server. If the virtuals start disturbing each other, you won't be able to fix it easily and it might be very expensive on the long run.

    I have to admit I don't have a lot of experience with Xen, and even less with OpenVZ. If I was building a server at home I would probably use Xen as it's free. At work I'm happy with VMWare ESX 3. Might be the performance is not on par with Xen (though it can't be far off), but the ease of use and management features make my job so much easier. The ability to move virtuals from one server to another without shutting them down (vmotion), easily view the state and resource usage of each virtual, high availability with clustering (one node goes down the virtuals are automatically started on another host), automatic resource balancing (one server get's overloaded, a virtual is automatically moved to an idle host without shutting it down) ect. make it the only viable choice for anything important that does not have an operator at hand 24/7.

    I'm not that impressed with the free VMWare Server. While it works in most things, it has very bad disk IO performance. Especially noticeable if you create new disk files or work with snapshots while running a lot of virtuals. It's ok for development or testing, but that's it.

    1. Re:isolation and ease of use by cerberusss · · Score: 1

      I'm not that impressed with the free VMWare Server. While it works in most things, it has very bad disk IO performance Same goes for Xen, if you use simple files as a backend. I suggest you create separate partitions for VMs. If that's not flexible enough, create a huge LVM partition and slice it in pieces for VMs.

      --
      8 of 13 people found this answer helpful. Did you?
    2. Re:isolation and ease of use by ovz_kir · · Score: 2, Informative

      In fact, free OpenVZ has most of what you tell about VMware. Live migration is here, and it does not require to have a SAN or a dedicated NIC, or pay for vmotion. High availability with clustering can be set up (see here). And finally, you don't have to pay a performance penalty if you want virtualization.

      The commercial product based on OpenVZ (i.e. Virtuozzo) has all that plus web-based and gui management tools, P2V migration tools etc. etc.

      It also makes sense to point out that Xen also has a live migration feature, although I haven't tried it.

      --
      -- Kir Kolyshkin, OpenVZ project leader.
  24. Yes, but does it run Linux\\\\\Windows ? by billstewart · · Score: 0, Offtopic
    I assume that most of these different approaches to virtualization will run some versions of the Linux kernel as a client, perhaps even most versions, and that you can talk BSDs into running on them as well (though it'd be particularly nice to know whether OpenBSD runs on them), and that you can run most of them on top of most Linuxes and maybe most BSDs (again, OpenBSD's the interesting one, due to security).


    But which ones of these things can run Windows clients, at least XP? VMWare can, User Mode Linux can't, but what about OpenVZ, Xen, and some of the others? There are times that it's convenient to have a Windows client OS, so I can run TurboTax and other Windows applications, but mostly I'd like a real OS underneath.


    Also, do any of these make USB devices visible to the client OS? Or do they all just have to network-mount resources that are actually mounted in the host OS?

    --

    Bill Stewart
    New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
    1. Re:Yes, but does it run Linux\\\\\Windows ? by DrSkwid · · Score: 2, Informative

      qemu runs Win2k. My AMDX2 3800 runs it using kqemu. I happily use it for testing things in I.E. It seems about as fast as my PIII 1Ghz laptop, though I've never actually measured it.

      --
      There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
    2. Re:Yes, but does it run Linux\\\\\Windows ? by Anonymous Coward · · Score: 0

      You don't want Xen or OpenVZ for the sort of things you're doing. Stick with VMWare (Player), VirtualBox or [k]qemu.

    3. Re:Yes, but does it run Linux\\\\\Windows ? by ppadala · · Score: 1

      > But which ones of these things can run Windows clients, at least XP?
      > VMWare can, User Mode Linux can't, but what about OpenVZ, Xen, and some of the others?

      Xen can run Windows without para virtualization using new processor VT extensions. OpenVZ's commercial implementation Virtuozzo can run Windows on Linux.

      > do any of these make USB devices visible to the client OS?
      > Or do they all just have to network-mount resources that are actually mounted in the host OS?

      Both Xen, VMware and OpenVZ all allow access to USB devices. There are multiple ways of accessing host resources from the guest with out mounting them over network.

  25. Hypervisor for both by gokalp · · Score: 2, Interesting

    We're using HyperVM from LxLabs http://www.lxlabs.com/ and it manages both OpenVZ and XEN. You can easily watch the performance penalties of both virtual machines from the same panel and migrate in between. So whenever someone abuses OpenVZ you can migrate it to XEN.

  26. VMWare is who they are going after by pyite69 · · Score: 1

    FWIW.

    I am a big fan of Virtuozzo and OpenVZ. I just wish vzstat would be included with the free stuff.

  27. Other way around for me by BestNicksRTaken · · Score: 1

    I used to have a Virtuozzo server, but after I started noticing poor PHP performance, my hosts migrated to a Xen3 machine and I must say the speed *increase* was quite impressive, and that was running with less physical RAM allocated, and more swap, on the same spec Opteron box.

    So maybe OpenVZ has some improvements over the commercial variant (seems backwards) or the article is talking about an old Xen2?

    I'm currently moving onto a real hardware colo system, which is more hassle, but gives me more control.

    --
    #include <sig.h>
    1. Re:Other way around for me by ovz_kir · · Score: 1

      my hosts migrated to a Xen3 machine and I must say the speed *increase* was quite impressive
      This probably relates to the fact that people usually run 5-20 Xen guests and 50-200 OpenVZ VEs on the same box.

      that was running with less physical RAM allocated, and more swap
      In OpenVZ, you should not take a look at what free or cat /proc/meminfo shows you -- instead you have to take a look into /proc/user_beancounters to see how much RAM etc. you have.
      --
      -- Kir Kolyshkin, OpenVZ project leader.
  28. Re:And OpenVZ works with FreeBSD? Windows? by Anonymous Coward · · Score: 0

    Then the whole article about 'compete with Xen' is bull. The computing world is bigger than GNU/Linux.

  29. I must be a sad, old geek ... by Marbleless · · Score: 1

    ... because I actually got that joke.

    Oh dear!

    --
    --I thought I was wrong once, but I was mistaken.
  30. Partners... by Anonymous Coward · · Score: 0

    Let's look at what are the companies in partnership with XEN and with SWSoft (OpenVX copyright owner). HP appears only on one list.

    http://www.xensource.com/partners/

    http://www.swsoft.com/en/partners

    1. Re:Partners... by smodak · · Score: 1

      HP is a partner to both companies, you just didn't look properly. Although HP is just a System Management[Xensource.com] partner.

    2. Re:Partners... by ppadala · · Score: 1

      HP actually works more closely with Xen than OpenVZ. For that matter, HP guys have contributed quite a bit of code to Xen (XenoProf, Perfmon come to mind). This study is done by people from U.Michigan and people at HP labs, a research division of HP.

      Pradeep

    3. Re:Partners... by stacey7165 · · Score: 1

      Hate to burst the "partner" bubble... but Hyperic is a systems management software provider (and a sister open source company by our investors) and also a Systems Management Partner for XenSource and VMware, and there is no systems management for Xen yet. Its in Beta now, and our CTO whose the first person to build a comprehensive management strategy for VMware is helping define the APIs with the Xen crew. VMware is more manageable today which is an unfortunate fact. And HP doesn't have a chance of catching up with the agility of Open Source to provide real support for ages. Its just a nice shiny name to have on the partner list... but it won't actually mean anything for a long time.

      In case it wasn't obvious, full disclosure - I work for Hyperic. http://www.hyperic.com/

    4. Re:Partners... by smodak · · Score: 1

      Well, I was replying to a post that talked of the presence of logos on the respective websites. Incidentally, I don't think I was talking about Hyperic or VMWare at all

  31. Much better isolation and security? Hmm... by ovz_kir · · Score: 3, Interesting

    Xen trades off performance for much better isolation and security.

    I guess I have to correct you here. Xen trades off performance for an ability to run different kernels, and this has nothing to do with either isolation or security. So, Xen is good when you want to run different kernels (different OSs).

    OpenVZ, on the other hand, employs a single kernel model, which makes it suitable for you if you only want to run Linux (different distros are possible, different kernels are not). But in this very field OpenVZ is way better than Xen -- not only in terms of performance, but also scalability, manageability, density, and usability.

    Speaking of isolation and security, OpenVZ runs on thousands of ISP/HSP servers, and everyone can buy a VE (Virtual Environment) for about 10-15 bucks a month. There one have a root account and can try to exploit the system in all the possible ways. So far those HSPs are not out of business yet, that practically proves the system is secure and properly isolated. More to say, security comes from the constant care, and we (OpenVZ team) do care for security a lot, see this blog entry for some more details.

    --
    -- Kir Kolyshkin, OpenVZ project leader.
  32. Hear, hear by flydpnkrtn · · Score: 1

    Just because a lumberjack doesn't know how to use his tools properly, don't blame the chainsaw because it ran out of oil and seized up

    Thnaks for OpenVZ btw! It's a great product, when used correctly

    --
    Here's to the crazy ones
  33. Performance is Rarely the #1 Consideration by Anonymous Coward · · Score: 0

    Performance is always a consideration when choosing a virtualization strategy, but it's rarely #1. If you want raw performance you're always going to "go native." If you want virtualization, you're always going to go for "good enough" performance that meets your primary objectives for virtualization: management, security, or an isolated need to run a non-native application. Price would be a fourth factor.

    For me, I chose virtualization for an isolated need to run a non-native application. Securing the application in a sandbox was second, since it was exposed to the internet, and managing everything on one box came in third. "Free-ness" was gravy. Performance just had to be good enough that end-users didn't notice.

    Here's a full summary of my experience:

    http://forums.srcds.com/viewtopic/4390

    My solution was to use containers, a Solaris feature turned out to be the best (and cheapest) solution to the 4-factor problem.

    Now that Solaris is open-source, we'll see if containers shows up on a FOSS OS near you.