In just a few short months, an open-source software package called Xen has been catapulted from obscurity to the limelight as many computing industry powers throw their weight behind the project.
Xen lures big-name endorsements
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Eugenia Loli
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This guy is doing an excellent blog about virtualization trends.
http://www.virtualization.info/
… I have even managed to install it and seen it work. Though not with more than one operating system. But I admit I got pretty excited about it.
http://www.fedoraproject.org/wiki/FedoraXenQuickstart
Will be in FC4 (perhaps).
Xen rocks – I look forward to doing a lot more playing with it in future. It seems like its new approach will usurp UML, which I also had fun playing with a while back. UML development seems to have slowed right down, whereas Xen is suddenly taking over. And as I’m a Cambridge guy, it’s cool to think it’s being created around the corner!
Can’t wait for the XP guest.
“Will be in FC4 (perhaps).”
yes. it definitely will be.
The question is, will this finally enable directx gaming in linux without rebooting?
Why are people excited about it? Why would you want to use it?
I don’t know if you are trying to be funny, but that is not xen’s usage profile. This is primarily for servers.
The beauty of it is that MS provided some of the initial capital for the Xen project then bailed when they realised where it was heading.
Virtualization can be a better jailer than chroot. Don’t know if you can install Xen as a normal user or that it even requiers a kernel patch but UML and colinux can be installed AFAIK as normal users and that is for some uses an advantage like “life” cd type stuff
so you can buy a beast of an x86 server for $4,000 – and use Xen to rent out 20 paravirtualized linux servers for $20 a month. You make your money back in 10 months, and after that – its all profit. peeps already do this with FreeBSD jails. I have no idea about UM Linux.
Does anyone know of OSes other than debian that make it easy to install to a loopback device? debootstrap is an extremely nice tool, a fedora or suse equivalent would make it easy to play with these OSes via XEN. A tarball of the very bare minimum install of either system would do as a substitute.
-Mark
<blockquote>so you can buy a beast of an x86 server for $4,000 – and use Xen to rent out 20 paravirtualized linux servers for $20 a month. You make your money back in 10 months, and after that – its all profit.</blockquote>
Once you factor in the cost of bandwidth and/or co-location, the economics look a bit different.
I use vmware but that is to test stuff. In this case it’s clearly intended to run multiple production OS’s at once (although I’m guessing testing would work great too for Linux). Linux does a pretty good job of having multiple services running on one server at once as it is so where is this most needed? I mean the seperation will always help to some degree with reliability and stuff but I’m not sure where it’s most useful and required. I’m guessing that it’s stuff I just haven’t needed or dealt with which is why I’m clueless
peeps already do this with FreeBSD jails.
Does it support live migrations (for example to dynamically balance the workload)?
“peeps already do this with FreeBSD jails.”
if you dont understand para virtualisation please read the documentation in xen.sf.net. you appear to be totally ignorant about these stuff
In the time it took you to call me ignorant, you could have re-read my post – and maybe understood it. Or maybe you would read it a hundred times, and still not understand it.
This is also a nice virtualization blog : http://about-virtualization.com
“n the time it took you to call me ignorant, you could have re-read my post – and maybe understood it. Or maybe you would read it a hundred times, and still not understand it.”
i read it once and its enough to see you are ignorant about it. i can confirm this again
Debootstrap is indeed nice. There are equivalents on the other distros, also:
Under SuSE, Yast has an option to install under a directory.
Redhat’s Anaconda tool can take a “–root” (or somesuch) argument that appears to do the same thing.
Xen is “mainframe-style” virtualisation for x86 machines. Its main strengths are in hosting and data centre environments.
Firstly, What Xen Isn’t:
* a way to run random unmodified OSs alongside Linux
* a way to run Windows applications under Linux
NB. Xen does include support for Intel’s Vanderpool extensions, which should eventually make both these things possible. Vanderpool hardware isn’t publically available yet.
What Xen Can Do:
* Run multiple virtual machines on a single box with _very_ low performance penalties relative to native execution
* Live migrate virtual machines from host to host, without stopping them (e.g. to load balance in a data centre).
* Suspend a virtual machine to disk and resume it at a later date, possibly on a different physical host.
* Xen ports of Linux 2.4 / 2.6, FreeBSD, NetBSD and Plan 9 are available, with the Linux ports being most popular.
There are a load of other features Xen offers now and a load of exciting new ones on the roadmap. See: the Xen homepage at http://www.cl.cam.ac.uk/Research/SRG/netos/xen/index.html and the roadmap at
http://www.cl.cam.ac.uk/Research/SRG/netos/xen/roadmap.html
Hi, Mark. I haven’t tried Yast yet. Anaconda seems like a serious pain to get working outside a RH box though…
Renting of computer resources can be done many different ways. You’re simply not smart enough to understand that. And how is Slackware doing nowadays?
Jails do not support load balancing. Some people rent them out as cheap shells and sometimes lightweight webservers.
Live migrate virtual machines from host to host, without stopping them (e.g. to load balance in a data centre).
That sounds very cool. Is this the kind of technology that Sun is using [with Solaris] to allow live upgrades of the operating system without rebooting the machine?
Hi Dylan,
Sorry to have taken so long in replying.
I found a reference to Solaris Live Upgrade – is that what you were referring to? This still requires a reboot, it just allows you to install / upgrade an OS in another disk partition *before* the reboot. This avoids the downtime of rebooting into an installer program but you still have to restart.
Live migration attempts to copy the contents of a running virtual machine gradually to another host. It does this using some adaptive algorithms to deal with modifications the virtual machine may be making to it’s memory contents.
Once the migration daemon has pre-copied as much as it thinks is useful, the virtual machine is stopped for at most a few hundred milliseconds, the state is fully synced-up and the virtual machine starts execution on the new host.
The downtime has been measured as 60ms for a running Quake 3 server and at about 300ms for an Apache server running SpecWeb. The idea is for the migration to be basically imperceptable to the user.
Hope that helps,
Mark