Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Linux Business Operating Systems Software

Desperately Seeking Xen 192

AlexGr sends us to an excellent article on the state of Xen by Jeff Gould (Peerstone Research). He concludes that the virtualization technology has some maturing to do and will face increasing competition for the privilege of taking on VMWare. Quoting: "What's going on with Xen, the open source hypervisor that was supposed to give VMware a run for its money? I can't remember how many IT trade press articles, blog posts and vendor white papers I've read about Xen in the last few years... The vast majority of those articles — including a few I've written myself — take it as an article of faith that Xen's paravirtualizing technical approach and open source business model are inherently superior to the closed source alternatives from VMware or Microsoft."
This discussion has been archived. No new comments can be posted.

Desperately Seeking Xen

Comments Filter:
  • by mwilliamson ( 672411 ) on Thursday June 28, 2007 @10:40AM (#19675883) Homepage Journal
    It seems that VirtualBox.org's product, fully virtualizing a copy of XP on my non-VT machine under a linux host OS, totally runs circles around Xen even on VT hardware as far as performance is concerned. Integration into the host enviroment is also quite beautiful. Why is there seldom a mention of VirtualBox in this arena?
    • Because.... (Score:3, Interesting)

      by Ayanami Rei ( 621112 ) *
      virtual box is basically QEMU with a much better KQEMU component that they developed on their own. This isn't very interesting because this is the same thing as VMWare or any other closed source Ring0-in-Ring1 emulation using polymorphic code.
    • by jsailor ( 255868 )
      I can't comment on why VirtualBox doesn't get more press, but I can confirm that I've had very good results using VirtualBox 1.3.x on fairly low powered machines. My guess is that it gets lumped under QEMU when comparisons are made.

    • Parallels, which is a commercial product, is one of the slickest VM's I've seen for desktop use. No one ever mentions them, either.

      2 cents,

    • Why is there seldom a mention of VirtualBox in this arena?

      I just installed virtualbox on Ubuntu Feisty to see what your fuss was about. I tried to install Windows 2000 in a VM and VirtualBox wouldn't let me type F8 to accept the license. No idea whose fault that is, but speaking for myself I can say only that vmware server 'just works' and thus I have no reason to use virtualbox, which does the same things but not as well.

    • IMHO VMWare took a huge chunk out of the open source alternatives when they released the Player and Server for free (as in beer).
  • Not just for xen - but if you are interested in virtualization in general. Lots of links to many other products - open and closed. So if you aren't into xen, but still want to know about what is going on in this space (to some extent - they don't even touch the stuff IBM is doing really) then it's worth the time.
  • you can't run Windows using Xen as Microsoft won't let you recompile the windows kernel... and this ability of being able to run windows on Linux is one of the things Microsoft allows to be done with the blessed versions of Linux for corporate customers. Normal mortals can't do it and will never be able to do it.

    Personally, I don't give a flying fig about being able to run Windows or windows programs on Linux... there isn't anything I want to do on windows that I can't do on Linux... (note the emphasis, I

    • by stevey ( 64018 ) on Thursday June 28, 2007 @10:56AM (#19676079) Homepage

      Not true.

      If you have VT-capable hardware then you can run Windows under Xen. You do need the hardware to support it though, and that is a problem for some home users. Recent AMD and Intel chips have slightly differing VT support but both work.

      I run Xen at home along with xen-tools [xen-tools.org] (which I wrote) to easily create new Debian guests on demand. These are used for software testing, hacking, and general service isolation.

      I think Xen is just now reaching "mainstream" in the sense that you don't have to be an early adoptor or major tinkerer to get it working. Now that distributions are including Xen kernels in their newer releases it really us available for all.

      • I've been messing with XEN for a week or two, thought it would help me out with debugging and maintaining multiple systems without the need for them. Picked up an AMD SVM CPU and tried it, running into a wall. The XEN list serv wasn't much help nor were the log files. In comparison Virtual PC 07 / VMWare on Windows worked flawlessly on the first try... I'd still prefer using XEN and might take a stab at KVM but wasting a week just to get to the boot screen without success was a little painful. FYI I tried C
      • Again, virtualization is for running Windows. Not Linux!

        Yeah, sure, there are a few weirdos out there.

        For most of us, there is no point in running Linux under Xen. We already gave Linux the native hardware. I guess somebody might want to run a Linux guest on Windows, but that'd be Wrong and is anyway unsupported.

        When I want to run a Linux app, I just run it. No problem. When I want to run a Windows app, I need virtualization.

        Xen is thus a solution in search of a problem.
        • Of course!! Why would somebody want to buy big hardware like a Sunfire X4600 M2 with 16 cores, 256GB RAM, 4GbE and multiple I/O slots to run multiple instances of Linux and/or Windows and/or BSD, and/or Solaris x86 when they could just run 1 instance and let the computing power of their server be use damn inefficiently?

          Nobody wants to make their data center streamlined and efficient for use of power and cooling, which in many ways costs more than the initial hardware purchase over a 4yr refresh cycle....

        • by DrSkwid ( 118965 )
          There are more OSes than Windows & Linux
      • by rthille ( 8526 )
        Any experience with Xen, NetBSD as Dom0 and Windows? I've got a NetBSD server that I'd like to be able to run Windows on, but VMWare on NetBSD seems out of date. I suppose I could use Linux for Dom0, run my server stuff on NetBSD as a DomU, but getting familiar with YAOS seems a pain...
    • Wouldn't it be nice if you could get a Xen rootkit for Windows XP and/or Vista?

      Perhaps it's a silly concept, but it could make work easier.

      But then there's the graphics difficulties.... the need for a hyperthreading CPU....and there's no support of course, for a rootkit ;)>
  • by interiot ( 50685 ) on Thursday June 28, 2007 @10:48AM (#19676001) Homepage

    If I have to maintain two separate OS's, I'd rather have the outermost OS (host OS) be the one that has the best drivers, the most hardware support. Also, since very few virtualization solutions work with 3D gaming (and even the one that does, it still has large overheads I think), you want your host OS to be the one that has all the games. So, for my purposes anyway, I need Windows as the host OS, and Linux as the guest OS. Xen doesn't run under Windows, only Linux. So that leaves me with either commercial virtualization software, or a few open source projects that haven't matured yet (eg. coLinux).

    (granted, having Windows on the outside makes your machine much less secure than the other way around, but personally, I'm more interested in having all my peripherals work the day they're released, and having all my games available)

    • Then what's the point? What special applications does Linux have that require you to run it in a VM on Windows?

      Usually people run Windows in a VM because they have some app that just doesn't exist on Linux, but that can hardly be the problem as most Linux apps are OSS and thus portable to Windows.
      • I think you have that slightly wrong - when you say "Usually people run Windows in a VM", I think you meant to say "Usually people run Windows".

        Some of them will take the plunge into the uncharted waters by running Linux in a VM so it won't trash their desktop settings, apps etc, ut make no illusion that the majority of people using computers are using Windows, not Linux.
        • Sorry to rain on your parade, but what I meant was that the reason people (who aren't on Windows) run Windows in a VM is because they need it for some app. Obviously people who already are on Windows have no need to run it in a VM.

          Why not use a live-cd if one wants to test it without committing? The inherent slowness of VMs makes it difficult to ascertain how well Linux would run, and the lack of 3d-acceleration means that none of the shiny things that draw in new people will function.
      • Re: (Score:2, Offtopic)

        by CastrTroy ( 595695 )
        I just can't wait till KDE4 is ready. Then I can have Amarok, Kopete, and most importantly Digikam running on windows. Hopefully it's stable, and runs well.
      • by interiot ( 50685 )

        that can hardly be the problem as most Linux apps are OSS and thus portable to Windows

        True. However, if you work with a large number of open source apps, or even just a lot of Perl modules... Usually these were designed from the start to work under Linux. Yes, the more popular ones compile under both, but sometimes it's a pain, and the less popular ones simply won't compile without extra work.

        Also, I just prefer Unix streams/forking/filesystem semantics over Windows. And sure, I use Cygwin/MinGW/e

      • Re: (Score:3, Insightful)

        by Wolfrider ( 856 )
        --Running a Linux Squid appliance in a VM, on your Win2k/XP laptop, while browsing wirelessly == Ads blocked + Internet content cached + More secure.

        --Testing (Freebsd / PC-BSD / Nexenta / Solaris / Linux) + ZFS + Samba in a VM when you don't have extra hardware to dedicate to it.

        --If you're not already a VM-type person, you wouldn't understand.
    • by jsailor ( 255868 )
      My situation is different, but with the same requirement for a Windows host OS. VirtualBox fills this need quite nicely. The latest release enables the use of VMware disk images, but I haven't tried that. You may wish to try out VirtualBox.
      • by interiot ( 50685 )
        I'd prefer to be able to dual-boot directly into Windows or Linux (for when I want the fastest performance in Linux, and give it 100% of the RAM), and also be able to run that Linux installation inside of Windows. However, this requires the VM to support booting off a separate partition, and apparently VirtualBox doesn't support that [virtualbox.org]. (yes, booting the same Linux setup under two very different sets of "hardware" has its challenges [vmware.com], but it is possible [wikia.com])
  • Full virtualization, as used in Xen, VMware and VirtualBox, has performance issues that are not yet well understood, but thought to revolve around dramatically increased L2 cache misses. I am not aware that any changes are in the works to fully resolve this.

    Operating system virtualization, as used for instance in OpenVZ has far better performance characteristics. This is the way to go at the moment for efficient and low cost data center support of Linux. The problem is that all virtual environments m

    • Full virtualization, as used in Xen, VMware and VirtualBox, has performance issues that are not yet well understood, but thought to revolve around dramatically increased L2 cache misses. I am not aware that any changes are in the works to fully resolve this.

      Hmmmm. No, not really.

      Performance problems with VMWare are almost universally associated with the added latency of the multiplexing/demultiplexing code that needs to be run to talk with shared I/O devices. This added latency in turn impacts bandwidth. "L
  • Using it... (Score:5, Interesting)

    by dmayle ( 200765 ) on Thursday June 28, 2007 @10:56AM (#19676087) Homepage Journal

    You can choose to believe the hype or not, as you wish, but I'm using Xen in my production environment, and it's simply fantastic. I've got friends with companies who are doing it as well, and it really changes how you think about administration.

    Of course, there are some learning curves. For example, how you manage 3-7 servers is completely different from how you manage 20-30, even if they are all virtual. There's a lot more emphasis on system images, isolating functionality, reproducing configurations. On the other hand, dev environments are so much easier to build-up and tear down.

    I just wish the OpenBSD port was in a usable state. The mercurial servers hosting it are often down, and even when they're up, I haven't been able to get a working kernel compiled from the sources (even after doing some of my own bugfixes). And last I saw on the Xen lists, Christoph Egger (the guy doing the OpenBSD port) submitted a security patch related to stack slamming, and the Xen guys were kind of like, "meh, security's not really a priority..."... Oh well, here's to keeping my fingers crossed

    • I have a VPS ("slice") at Slichehost [slicehost.com] and it's the best thing since... well, you know.

      Seriously, it may not be right for all applications, and things like Solaris' zones/containers are quite awesome (much more control over IO, fair share scheduling, etc.), I have one of those too at Joyent, but (like many things Linux) it seems to work, be fast, and get the job done at a great value.

      I have seen people complain when they have an app that's IO bound and there's another slice with heavy IO needs--looks like IO
  • by Aeonite ( 263338 ) on Thursday June 28, 2007 @11:03AM (#19676177) Homepage
    Is that Gordon Freeman ruined it.
  • by eno2001 ( 527078 ) on Thursday June 28, 2007 @11:08AM (#19676207) Homepage Journal
    Not only that, but I've been running it in a production environment for about a year and I'm about to deploy a HUGE set of servers as VMs using it. Xen beats VMware in one arena: price. If you use the open source version (which I'm doing) it's free. Only VMWare's ESX can compare to Xen. And unlike some people here have been saying, you DON'T need a special processor for Xen unless you plan to virtualize Windows. In my environment, I'm only virtualizing Linux, so I can use regular x86 CPUs dating back to 1998 for Xen. The only exception is the deployment of Zimbra I'm going to do. It requires Redhat Enterprise Linux 4 and NPTL, so I can't run it paravirtualized, it must run HVM which requires the special processors. However, who today isn't getting new hardware with HVM support?

    Currently my two Xen servers here at work serve out about four VMs (all paravirtualized on older hardware) for critical and I/O intensive tasks like proxy servers for nearly 1000 machines, or the firewall syslog server for a dual T3 link with about 5000 users behind it sucking the bandwidth dry. So you can't claim it doesn't perform either. Now, if you want point and click administration and an easy set up, then yeah, Xen is behind the times. But performance wise it's leaps and bounds above VMWare. Trust me, I was a VMWare fan before you were in virtualization diapers. And I still am for some applications. But for places where I need something to be cost effective AND give me the features of VMWare ESX, Xen is the ONLY answer.
    • by div_2n ( 525075 ) on Thursday June 28, 2007 @11:45AM (#19676707)
      The only exception is the deployment of Zimbra I'm going to do. It requires Redhat Enterprise Linux 4 and NPTL

      Last I checked, Zimbra runs on Ubuntu 6 [zimbra.com] just fine.

    • by tji ( 74570 )
      "Just Works" is overstating it quite a bit. Based on my experience, and looking at the other comments here, it's more like Xen "mostly works, after a great deal of learning, googling, and experimenting". Maybe once you've ramped up on it it works well. But, saying it "Just Works" is clearly not the case.

      The Xen experience has improved a lot. In Fedora 7, I just had to select the Xen kernel+apps for a package install, and the Xen infrastructure was pretty easily installed. But, getting client VMs ru
      • I agree. It doesn't "just work" by any stretch of the imagination. When it does work, it's great, but there's a whole mess of shell scripts working in the background which don't handle error conditions very well and you often get presented with very cryptic and often quite misleading error messages ("Backend scripts not working" is one of my favorites).
  • Lies, all lies (Score:4, Informative)

    by C_Kode ( 102755 ) on Thursday June 28, 2007 @11:08AM (#19676211) Journal
    Another question hanging over Xen performance concerns the availability of paravirtualized drivers for Windows.

    This isn't true completely. The problem is you cannot get these drivers by downloading the OpenSource Xen. You MUST buy the XenSource version. If you run Windows on the *complete* open source version, your network throughput is going to suck like you would not believe. You have to use the XenSource version to get the paravirtualized drivers that bring the network performance closer to what it should be. Virtual Iron has a set of drivers also. (which I believe are better than Xen's, but don't hold me to that)

    I found a lot of great insight about virtualizing from Xen to VMWare to Virtual Iron and others on this site. http://ian.blenke.com/xen [blenke.com]
  • I've tried both and VMWare is just better. I respect Linux/GPL and the OSS movement, though the main reason I use linux is not just those reasons it's because IT WORKS. So when it comes down to Xen or VMware I use vmware because it works better.

    Xen is FOSS so there is potential for them to catch up and with the nature of FOSS new ideas can be tossed in easier. So when that day comes I'll gladly switch over, it's just not there yet.

  • Guaranteed Results (Score:5, Informative)

    by catdevnull ( 531283 ) on Thursday June 28, 2007 @11:26AM (#19676421)
    If you want to get a colorful thread of comments started on slashdot, there are 3 ways to do it with guaranteed results:

    1) Say something bad about linux (or about Apple).

    2) Say something good about Microsoft (or about Apple).

    3) Throw a grenade in the room about Open Source software like this:

    The vast majority of those articles -- including a few I've written myself -- take it as an article of faith that Xen's paravirtualizing technical approach and open source business model are inherently superior to the closed source alternatives from VMware or Microsoft.

    I'm not making any value judgements here--I'm just amused.
  • I'm getting a Macbook soon, and I want to play around with virtual machines on it.

    Is it possible to install e.g. Debian as my host OS, apt-get install xen, and then install Mac OS X inside a Xen virtual machine? This computer has a C2D processor, which supports the Intel VT instructions. I'll also do the same with Windows XP and Vista, and Ubuntu.

    If it will work, how well? Will it be a transparent install so that X can directly access the 3D acceleration hardware?

  • My company is currently using Xen on something like 40 "virtual machines" on 6 "real machines." Works almost flawlessly. Runs heavily-used multi-gigabyte MySQL databases and Java web apps without complaining. You can move virtual machines between real machines while they're under load, with a 6ms delay. If a developer wants to try something weird, go ahead. If you hose the system, I'll just re-image it and have you going again in 5 minutes. There's nothing wrong with Xen at all, if it's done right. It
    • You can move virtual machines between real machines while they're under load, with a 6ms delay.

      That's really interesting. See, the authors of Xen say live migration isn't ready and that it's unstable. I have deployments of redhat, suse, and open source xen that prove that with swarm-cloud migration testing (just put all the vms into flight constantly, ping-ponging around to various hypervisors). Meanwhile, Xen Enterprise does not today feature live migration. Why? Did I say that it's not ready, and that th
      • Re: (Score:3, Interesting)

        by BJZQ8 ( 644168 )
        Well, I've done numerous tests of live migration, and it works for me. Do I know something they don't? I don't think you can say either way. Perhaps on somebody else's network, it might not work. But I've done migration under heavy load and not had any failures, zombies, or crashing of Dom0. I had to clarify the 6ms delay in another post. Here's the way I put it, simplified because I screwed up the formatting...

        ping...64 bytes from xxxx...5 ms
        ping...64 bytes from xxxx...5 ms
        ping...64 bytes from xxxx..
        • Re: (Score:3, Insightful)

          by Courageous ( 228506 )

          I understand the latency of the switchover. It will be dependent on the size of the volatile set of memory that needs to be transferred between the save/restore cycles. I.e., this will be virtual machine-dependent, and tend to increase linearly with the virtual machine's memory footprint and memory utilization.

          "Data center readiness," to me, does not mean a few servers running Xen. It means many, many servers, taken from at least superset of servers taken from all the mainstream enterprise server vendors, i
  • Xen's Maturity (Score:4, Insightful)

    by Krondor ( 306666 ) on Thursday June 28, 2007 @11:47AM (#19676757) Homepage
    He concludes that the virtualization technology has some maturing to do...

    I RTFA and it says very little about the maturity of the actual Xen technology. The article is more a point about several non-related factors;

    1.) There is a lack of pretty management interfaces.

    True, but these are in the works from Red Hat, Novell, XenSource, and various other ends. Already some of them look pretty promising, but if you are a real admin you don't need them in the first place. There is nothing wrong with using the command line tools to manage your Xen virtual guest environment.

    2.) There is a lack of references for companies using Xen.

    How does this relate to the viability of the Xen virtualization? Yeah it makes management feel nice and fuzzy that others are using something, but this does not relate to how well the Xen technology performs. I also suspect that like many open source projects, there are many people using it that do not report it. Novell has personally contacted me and my company to ask us to assist in their new paravirtualized Windows drivers initiative and then be a reference for the technology. It seems that at least some companies are moving to address this, at any rate.

    3.) There aren't many benchmarks about Xen versus VMWare.

    VMWare does not allow benchmarks they do not approve of. It's in that draconian EULA you agreed to by using it.

    4.) It's awkward to paravirtualize Windows.

    Yes, it is. Novell signed the soul sapping agreement with MS and as such is pushing some paravirtualized drivers for Windows. The article continually talks about woes with Xen on Red Hat. Red Hat didn't sign the agreement and will require some much more intelligent coding to make this happen. It might never happen, so for Windows it's full virtualization with VT (or AMD's equivalent) or bust. Sorry, use SUSE for it or use full virtualization. It's an MS issue not a Xen issue.

    5.) MS's new Viridan Virtualization Platform is using paravirtualization as well.

    Yep, that should be a testament to the approach versus VMWare. Though it is interesting that VMWare now has a Linux kernel virtualization implementation similar to KVM. It seems VMWare is headed to paravirtualization as well. Obviously Xen did something right.

    6.) There is a lot of competition.

    True. How again is this relating to Xen as a virtualization technology.

    Again, I'm not saying Xen is perfect. It definitely has issues and room to grow. I'm just saying that the article makes little, if any, relevant points to Xen's virtualization technology.
    • by drsmithy ( 35869 )

      True, but these are in the works from Red Hat, Novell, XenSource, and various other ends. Already some of them look pretty promising, but if you are a real admin you don't need them in the first place. There is nothing wrong with using the command line tools to manage your Xen virtual guest environment.

      It's not just about pretty pictures, it's about usability. For example, Xen is a bitch to setup with any sort of non-trivial networking environment (eg: multiple vlans, bonded interfaces, etc). You freque

      • You frequently have to write your own scripts to make it work in such situations, but this requires a very good - arguably completely unnecessary - understanding of what's going on behind the scenes.

        You seem to be complaining that the Xen hypervisor doesn't do anything with networking. That's not what a hypervisor is for. Setting up virtual networks is outside the scope of a hypervisor; that's why you need other tools. It would be like complaining 10 years ago that Linux worked fine for process management, but that it was a pain to set up networking, that you needed to edit all kinds of scripts and nonsense. That's got nothing to do with the kernel, but with the lack of supporting tools to make c

      • Re: (Score:3, Insightful)

        by FireFury03 ( 653718 )
        For example, Xen is a bitch to setup with any sort of non-trivial networking environment (eg: multiple vlans, bonded interfaces, etc).

        I'll agree with this, although it isn't the hypervisor's fault - it's the userland stuff that's at fault. For example, Xen doesn't appear to support IPv6 *at all* in routed mode, I had to hack up my own scripts to do it (and I'm seriously considering moving over to bridged mode in an effort to simplify and standardise my system). But I'm curious - do other virtualisation sy
    • There is a lack of pretty management interfaces.

      This seems to be one of his main disappointments, in fact -- specifically, that RHEL 5 doesn't have pretty management interfaces. (The only mention of XenSource and Virtual Iron's management interfaces seems to be to re-emphasize that RHEL's GUI is really bad.)

      The Xen hypervisor is an engine, not a car. Xen is in some ways similar to where Linux was in the late '90s -- the kernel worked great, but the GUI was way behind. And the fact is that corporate customers need a complete solution, not just a gre

  • I'm primarily a VMware VI3 user, but I've been starting to do more with Xen lately. I have to say, Xen is very impressive in what it accomplishes. It's very stable, and has the capability to do some really advanced stuff. That being said, it can be a real pain to get some of those advanced features working. For example, running Xen in CentOS 5, I had a server with two NICs, and I wanted to setup a second bridged interface for the second NIC. It took way more effort than it should have to get that worki
  • by tji ( 74570 ) on Thursday June 28, 2007 @12:02PM (#19677001)
    I have been trying to use Xen at home to test it out and compare it to VMWare, which I've used at work. Once you manage to get Xen clients working, it's fine. It does a good job of running VMs, and can be used to partition resources on a powerful machine.

    But, the main problem is the steep learning curve for getting Xen running in the first place. The (python based) management GUIs included with Fedora or Ubuntu are weak at best (although, slowly improving.. the UI in Fedora 7 does manage to make setup easier than the command-line alternative). The ongoing management / monitoring of VMs is okay, but weak in comparison to VMWare.

    There are also a lot of little quirks in Xen. Installing Win2k in a client VM required a lot of searching for how to attach an ISO image to a running VM (it's not a simple GUI operation like in VMWare/Parallels/VirtualPC, it requires a terminal command with unintuitive options, which never worked for me.. I finally dug out my CD and got the physical CD drive to attach to the VM). Windows VMs have an odd issue where the mouse pointer is offset form the actual pointer (it's a known issue, and is helped by turning off mouse acceleration in Windows preferences, but it is still a problem). Installing client VMs can be challenging.. Ubuntu feisty wouldn't install until I set the VM as a Solaris client, and after a few other tweaks it finally installed and worked fairly well.

    Most of the Xen problems are solvable, after playing with command-line tools, figuring out poorly documented parameters, and lots of googling. At the end of the day, it's one of those "Xen is free, if your time has no value" type things. VMWare Server is probably a better option if you just want it to work for home/free uses. For commercial use, VMWare ESX Server is the way to go. It has simple VM setup for many client OS's, excellent management of large groups os Hypervisors and virtual machines.

    The commercial alternative from XenSource (free to use, but limited to 4 VMs; or less restricted versions for increasing $$) offer a better management UI, but are too restricted for my taste. The management app is much better, but not as good as VMWare.. If I'm going to pay for one, I'll go for the best option.
  • Not enough market share and immature (optional) GUI == Not Ready for Prime Time.

    "Oh my. Editable XML configuration files, obscure command line interfaces, grayed out options in the GUI? Thanks, but no thanks. This thing doesn't sound like it's ready for prime time in Data Center USA."

    I say if you can't use the command line YOU'RE not ready for "prime time in Data Center USA."
  • Data Center USA (Score:5, Insightful)

    by fyoder ( 857358 ) on Thursday June 28, 2007 @12:23PM (#19677283) Homepage Journal

    I stopped reading the article with this quote:

    Oh my. Editable XML configuration files, obscure command line interfaces, grayed out options in the GUI? Thanks, but no thanks. This thing doesn't sound like it's ready for prime time in Data Center USA.

    Are sysadmins at "Data Center USA" morons? "Oh nooo, command line time, I hate that. Oh nooo, my option I want is all grayed out! Help me, help me! Oh I am so sad now."

    Deploying vm stuff is not the same as using a word processor. "Data Center USA" is in real trouble if their sysadmins aren't any smarter than regular desktop users.

  • Two words: OpenVZ (Score:3, Insightful)

    by pyite69 ( 463042 ) on Thursday June 28, 2007 @12:56PM (#19677745)

    If you are running the same OS on each VM on a server, OpenVZ is the best.

    Performance is great, good control over resources (with the glaring exception of disk IO operations, which they are working on).

  • The only reason so far that's stopping me from using Xen is that it doesn't support frequency scaling and other power management of my laptop.
    Sticking with VMWare Server for now...
  • by Tracy Reed ( 3563 ) <treed@@@ultraviolet...org> on Thursday June 28, 2007 @02:19PM (#19678897) Homepage
    Xen saved my former employer a bunch of money and gained then great flexibility and reliability. They use an AoE (ATA over ethernet) SAN so the compute nodes are totally diskless and all of the data and root filesystems are on the SAN. Now they have email, database, web serving, nearly all of their critical functions in a highly available xen-aoe cluster. I am working with them to release all of the codes and configs in production and we are setting up a website at xenaoe.org (not up yet, but soon) to host the project.

    Here is something I wrote up about this architecture for the company when the project went live:

    What is Xen?

    Xen is a free virtualization system similar to VMware but different. It allows us to run multiple servers/operating systems all on one physical piece of hardware while providing isolation between them.

    What is AoE?

    AoE is a SAN technology. Similar to Fibrechannel (but far less expensive) or iSCSI (but far simpler and more efficient).

    What are the advantages of Xen and AoE for our company?

    Xen allows us to more efficiently utilize our hardware resources. The majority of cpu power on your average computer goes unused. Even on servers. They just sit there waiting for something to happen. Even if we get a web request every second the time between one request and the next is an eternity for a cpu running at 2 gigahertz. But powerful cpu's are needed for those short bursts of activity. By using Xen to run multiple servers in their own domains (areas of memory) completely isolated from each other on the same physical hardware we can squeeze more utilization out of our existing CPU's/servers. This means we can get by with fewer CPU's, less rackspace, use less power, and require less air conditioning. By encapsulating the servers into this sort of infrastructure it also allows enhanced management capabilities by allowing the administrator (such as myself) to be able to get console access on the server or restart the server while remote instead of having to drive to the datacenter (which in our case is a 30 minute drive down to Kearny Mesa).

    AoE allows us to put a bunch of disk in relatively inexpensive and low CPU powered servers on the network and allow the rest of the servers to access it exactly as if the disk were locally installed in that server. This is advantageous because we can now aggregate all of our disk into one system and treat it like a pool of storage where we can dole out an appropriate amount of disk to each server (often only 10 or 20G is needed) instead of having to put in a dedicated 250G disk which is the minimum you can easily buy these days and waste a lot of disk and power to run it.

    The combination of Xen and AoE allows us all of the above plus some interesting fault tolerance abilities. There are now two levels of redundancy in our disk systems and an extra level of redundancy in the cpu's also in that if one cpu fails (or the associated motherboard, RAM, or network card) we can easily switch the servers that were hosted on that machine over to another cpu on the network with either zero or very minimal downtime whereas previously that kind of failure would have required me to drive down to the datacenter and shuffle hardware around or buy new hardware to replace the failed system which all takes time and can result in prolonged downtime.

"I'll rob that rich person and give it to some poor deserving slob. That will *prove* I'm Robin Hood." -- Daffy Duck, Looney Tunes, _Robin Hood Daffy_