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Xen 4.1 Hypervisor Released
LarsKurth writes "The Xen.org open source community just released a new version of the Xen Hypervisor, Xen 4.1. Feature highlights include a new prototype scheduler for latency-sensitive workloads, better support for very large systems (>255 CPUs, 1GB/2MB super page sizes), new security features, and many others. During the development cycle of Xen 4.1, the Xen community worked closely with upstream Linux projects to ensure that Xen dom0 support and Xen guest support are available from unmodified Linux distributions. The release announcement contains a full list of changes."
Oracle is trying to enter the x86 virtualization market with Xen in a product called Oracle VM. I've used it, and it's ugly. Besides the PHB marketing tagling of "you can run Oracle on the entire stack!", I've seen no technical reasons to use it over KVM or VMWare in the enterprise.
Ever since IBM stopped contributing this Xen two years ago, the pace of Xen development has been pathetic. Not sure why this project is still alive.
Amazon (arguably the biggest cloud service provider) uses Xen exclusively.
I run openSuse 11.2 which includes integrated support for hypervisor. When I attempted to implement it it required a kernel adjustment of some sort and a reboot. When I rebooted there was some issue with my screen configuration and x would not start up. I gave up and installed virtualbox instead which is freaking rad and worked flawlessly. Is there an advantage to xen that makes it worth the hassle?
People say my sig is the best thing about me.
XenServer, despite being pretty much the same product, is crap. Somehow, Citrix managed to ruin something that, at the time they bought it, ran well and was fairly solid. They changed enough to make it kludgy pile.
Because they have not noticed that IBM abandoning them and KVM removing the need for them means they are dead. Give them time.
Obligatory XKCD
I tried and failed at Xen 4.0 after using Xen 3.x successfully sometime beforehand - I have been waiting for all those involved to update, stabilise and simplify Xen - looks like it is coming very soon.
Redhat not using Xen for sometime now, fair enough, I'm not using Redhat so it won't bother me much.
But why not use its own Virtualbox? I find it a lot more usable than Xen. Well, anything is easier to use than Xen.
Oracle is trying to ENTER the x86 virtualization market with Xen in a product called Oracle VM. I've used it, and it's ugly. Besides the PHB marketing tagling of "you can run Oracle on the entire stack!", I've seen no technical reasons to use it over KVM or VMWare in the enterprise.
You keep using that word. I do not think it means what you think it means. http://www.virtualbox.org/
Here's hoping Oracle doesn't start charging for it -- just after releasing some updates the mess up the free version. But you know they will, being Oracle and all. I suggest keeping older versions of the packages in case they do that. After all, if all you need is to run XP for some things, or a few spare linux distros -- you don't need to change the VB platform, ever, unless a new one has new features you need.
Why guess when you can know? Measure!
If you want to run a ton of VMs on a server, Xen is great. It's fast and stable once you sort through the mess of getting a kernel that both supports your hardware and runs well as a Dom0 (the "host" machine).
And for the past year or two, most distros have shipped kernels which would boot just fine "out of the box" on Xen virtual machines.
It's what most "cloud" or VPS providers run (including Amazon, Rackspace, Slicehost, Linode, etc).
However, if you're running a desktop and want to virtualize, Xen is probably going to be a HUGE pain in the balls, with no real benefits. Just use KVM or VirtualBox.
I'm pretty sure that Virtualbox and Xen are(in addition to architectural differences) aimed at substantially different uses of virtualization.
Virtualbox, though there is nothing specifically stopping you from using it otherwise, is pretty much aimed at the "second and/or test OS on primary desktop" use case. Run whatever primary OS, run a small number of secondary OSes or virtual test boxes because RAM is cheaper than a rats nest of towers and KVM switches. This shows in the fairly simple configuration, easy support for peripheral-passthrough and graphical guest OS window, and lack of interest in things like automated guest migration.
Xen, by contrast, is aimed much more at the "pool of VM servers supporting some large number of VM instances that are mostly there to interact over network only" style. Nothing prevents you from setting up your desktop as the dom0 OS, and using it like Virtualbox; but it would be a pain and not clearly beneficial. On the other hand, you get much more concern for large memory spaces, guest migration, and similar things.
This isn't a precise analogy(since I suspect that they share somewhat more, just for cost reasons); but asking "Why use Xen when you could use Virtualbox?" is sort of like asking "Why use VMware ESX when you could use VMware Workstation?"
Yeah, so Xen has all these fancy features. So does KVM. So does VirtualBox. So does VMWare.
The underlying features aren't really the important point - they haven't been for some time and that isn't going to change with this release. The important features right now are manageability - is there a pretty GUI to show the managers? A programmable, easily scriptable API? - and full feature-parity with the likes of VMWare. (Doesn't have to be parity with the enterprise versions, just parity with the free VMWare server will do).
And by feature parity I do not mean "feature parity in theory but it doesn't work in practise because we worked it out by looking at the names of all the features, guessing what they meant and replicated them. Further investigation shows our guesses were wrong in a few places, but hey..."
Virtualbox is their consumer x86 virtualization product, Oracle VM is their x86 enterprise virtualization solution; clusters, high-availability, etc.
Think of it like this:
Virtualbox = VMware Workstation
Oracle VM = ESX/vSphere
Bummer.
Watch this Heartland Institute video
Does anyone actually use this?
I was sorta hoping this was about a new Vuzix competitor...
Reality is prettier inside my head...
it was owned by xensource, now owned by citrix, really unlikely that IBM contributed more than the owners.
Thanks playing FUD and toeing the party line on KVM
I've been working for weeks toward setting up a test box for Xen (I want to learn it for work). In my research i found the webmin-related product cloudmin which works for both Xen and KVM. Haven't tried it yet, hopefully it's as good as regularly webmin. That'd provide the GUI, not sure about the other stuff.
"UNIX is very simple, it just needs a genius to understand its simplicity." -Dennis Ritchie
Also, I'd like to point out one stupid thing: VirtualBox won't let you allocate more than half of your physical memory to VMs. Even if you built the machine with excess of RAM so you could do just that... Want to run 2 1GB VMs in a 4GB machine with integrated (RAM stealing) video? can't do it, even if the machine isn't running anything but VMs.
Is that some kind of architectural limit, or has somebody neglected to remove the "stop the machine from thrashing horribly" heuristics from back when 16GB desktops were science fiction?
Just curious
http://saveie6.com/
You have heard of Amazon EC2 right?
Maybe because it's the greatest virtualization technology for servers (see AWS, Openstack, and so on)? Because it's the virtualization of choice for cloud computing, with live migration working like a charm? Or because KVM doesn't offer the kind of functionality one may need, like being able to mount a partition directly in dom0 when you use LVM, and such kind of thing? Because it has great CPU schedulers, and lots of new things for nested virtualization which other products don't have? Or is it because other big companies like Oracle, Intel, Samsung, Fujitsu, or Citrix are working hard with a lot of staff on it? Maybe it's because Xen developers have new Intel hardware before they are out, and could develop things like SRV-IO support before everyone? Take your pick!
By the way, I wonder why you are saying that the pace of Xen development is pathetic. Have a look at the xen-devel list, and see how many patches are sent to the list every day, or read LKML, or see the latest Xen patches upstreamed to kernel.org kernels during the current 2.6.39 merge window, and you might change your mind.
Xen isn't great for desktop, but for servers, there's nothing like it, lots of people know it, and contribute to it.
But isn't a contributor.
Maybe you should give a go to our DTC and DTC-Xen then? Both are included in Debian and Ubuntu ...
Thomas
Don't believe the FUD in these party-line comments. I run a NetBSD Dom0 with now 7 Red Hat DomU's in an LDAP/messaging cluster on a single server, scoped to 10 concurrent VMs hitting iSCSI cluster targets.
It's not a desktop product. It's designed for high-availability and dense clustering, has a mature codebase and tools, and it works well. And yes, Red Hat 6 runs just fine as a DomU out of the box, and can be a Dom0 as well, if you like (although not "supported" by Red Hat, still quite functional).
I suspect it's neglect.
Xen is good. KVM won't run on my intel atom boards anyway... No point in expecting all cpus to support hardware virtualization.
HVM is slower than Paravirtualization anyway... as a rule.
You must've stopped looking a while ago. Admittedly it looked very grim a couple of years back when KVM hit the big time and Xen was stuck with their aging fork of 2.6.18 and not getting on well with the Linux kernel team.
But it's different now - the last year or so seems to have been the busiest I've ever seen the Xen devel list and the pace still seems to be increasing. And I've been following along since 2.x or so about 6 or 7 years ago. Additionally the relationship with the Linux kernel upstream seems much improved now too.
Most of the big or well known "cloud" or virtual Linux server providers still seem to use Xen - eg EC2, Rackspace cloud, Softlayers cloud, Linode, Slicehost, Rimuhosting etc.
Consider the Linux kernel from the criticisms you've just made. Does Linus's tree have important features for manageability? Does it have a pretty GUI to show managers? Is it programmable and easily scriptable? The answer is, of course, no; management, GUI, scripts & come from other projects built on top of the Linux Kernel.
The same is true of Xen. The core Xen project is about operating-system-level functionality, just like Linux is. It is, if you will the engine; but what most people want is a car. The scriptable engines, GUI, management tools, and so on are of a completely different type of programming than OS programming, and should be separate projects.
And these projects exist. XenServer is such a system that includes everything that you describe; and the free-as-in-beer version is very powerful. For those wanting an open system, the Xen Cloud Project is a community-oriented version with feature parity, having been based on the same codebase. Additionally, there are people working on porting libvirt bindings to Xen 4.1, so that any management and GUI software that uses libvirt as a backend to manage KVM can also manage Xen.
TCP: Why the Internet is full of SYN.
Ref please? IBM has never been a major contributor to Xen, and Xen development, especially over the last year, has been just fine.
The project is still alive because it is useful to thousands of organizations (including large corporations like Tesco, Bechtel, Fujitsu, SAP, cloud providers like Amazon and Rackspace, to name just a very few), and thus worth the time of various organizations (including Citrix, Oracle, AMD, Intel, and yes even RedHat) to pay developers to work on improving it.
Are any major corporations with a significant deployment of KVM or VirtualBox?
TCP: Why the Internet is full of SYN.
Is anyone using KVM for server consolidation?
KVM is a great tool for having a secondary VM on your desktop. In fact, one of the Xen developers who works remotely (and thus doesn't have the same access to a big farm of test hardware) actually uses KVM to do Xen development, when what he's working on doesn't require any hardware virtualization features. But if what you want is a dedicated VM-hosting box, Xen is the way to go.
TCP: Why the Internet is full of SYN.
But does it finally support 24 and 32 bit color depth on the desktop? That was a huge stopping/stumbling block for me on integrating Zen into our datacenter. We ended up going with VMWare's ESXi because it's the only hypervisor that supports 24 bit color depth that I found. I would really have preferred Xen but they seem to have completely ignored the video memory segment of their product.
Anyone know why this is? It seems like it would be a simple addition.
Lots of people do. KVM is what RHEL uses and pretty much everyone else as well. Xen is dead.
KVM has done live migration for ages now. Passing usb in kvm is quite easy, heck you can do it with qemu commands if you want.
Sounds like you are out of touch with reality.
Ah, that was your prime opportunity to bring in actual examples. The lack thereof makes it clear to everyone that "Xen is dead" is just FUD.
TCP: Why the Internet is full of SYN.
Something, I'm really missing is a stronger "passthrough" implementation than Intel VT-d/AMD IOMMU that allows any hardware to be passed through to a guest OS / domU such that I can use Unix/Linux as Dom0 and play fully-fledged DirectX11 games on a multiway SLI/CrossFire on a Windows guest machine.
.net or DirectX will shrink into wrappers that will provide whatever specific resources that are requested by the program to be run. So if you run a MacOS program the wrapper will parse runtime libraries based on the MacOS frameworks to the program whereas a Windows program will use Windows runtime libraries through this wrapper and so on.
I have the dream or vision that operating systems will grow into more simplistic hypervisors in the future. System environments that provide APIs such as
So there will be a separation between the hardware and the operating systems by an abstraction layer where different wrappers (that used to be operating systems) share the underlying hardware with each other. There will no longer be a question whether you use Windows, MacOS or Linux. You just use whatever you prefer as a base OS and use whatever is needed to run the applications you want, which in reality could mean that you run several operating systems simultaneously on the very same machine.
This separation has already begun, ZFS is a good example of that. The ZFS file system looks at the hard drives as a storage pool and the user is not concerned with the physical characteristics of the partitions and where the sectors begin or end. I didn't like it at first but later found that this approach is ingenious. So I see it as a natural step that the rest of the hardware will undergo the same transition. I also think a lot can be done with the UEFI framework in this regard.
Actually Xen dom0 support *IS* already in mainline upstream Linux kernel as of 2.6.37 ! Some xen backend drivers are still missing from upstream kernel, but upcoming Linux 2.6.39 includes xen-netback backend driver, and xen-blkback driver is planned for 2.6.40. http://blog.xen.org/index.php/2011/01/14/linux-2-6-37-first-upstream-linux-kernel-to-work-as-dom0/ The pvops framework was merged to Linux 2.6.24 a couple of years ago, and Xen pvops domU support was first usable in Linux 2.6.26. So Xen support has been in upstream Linux kernel for 12 major kernel releases already! Also Redhat RHEL6 runs as Xen VM, both PV and HVM, just as pretty much any distro does nowadays. Upcoming Fedora 15 has a Xen dom0 capable kernel, and it is expected that Fedora 16 will have fully featured Xen dom0 support out-of-the-box (including all the backend drivers that are being upstreamed atm).
Actually Xen is far from dead. Development is very active, and most of the important kernel-related patches have been upstreamed and included to Linux, including the much discussed Xen Dom0 support. So the situation nowadays is very different from a couple of years back.
Great post! Many people don't seem to realize a lot has changed in the Xen-land during the last couple of years.. Xen dom0 support is now included in the upstream Linux kernel, and Xen developers are at the moment actively working on upstreaming for example qemu-xen to upstream Qemu. And for people who don't want to "do-it-yourself" there's Xen Cloud Platform (XCP) available.. opensource dedicated virtualization platform shipped as installable ISO image. http://xen.org/products/cloudxen.html .