“In the past month, there’s been much ado about Xen in the online community, both from developers, columnists and the SearchOpenSource.com audience at large. First Xen was given the green light to become an open source killer app, thanks to the work done by companies like XenSource with its XenOptimizer 3.0 upgrade. Meanwhile, some users and analysts said the technology was unproven and had a ways to go before the killer app label would fit.”
Xen seems to have made great strides. Whether or not the term “killer app” applies or not is irrelevant. If I can run multiple linux ditros on one box with no changes to source code and almost no performace hit, I’m stoked. If one day I can say the same about running XP or Vista, I’ll be very pleased.
All I am waiting for is to have an easy way to move running os’s across systems without any downtime.
A nice gui to view all of the virual hosts and server load etc. will be nice when someone develops that as well.
Disclamer: I work on Xen, do paid consulting for XenSource.
You’re in luck, then! Xen’s Live Migration feature will migrate running virtual machines between Xen hosts with only a few hundred milliseconds downtime (at most). The best downtime I remember hearing of was around 60ms for a running Quake 3 server. You’ll need some sort of storage solution that’s accessible from both hosts, like GNBD, or iSCSI, or a SAN. The kind of storage used can be transparent to the guest.
For the GUI side, there are a few GTK-based Xen management apps. There’s also Enomalism (http://www.enomalism.com) and of course the XenOptimizer (http://www.xensource.com/products/xenoptimizer.html). Optimizer does drag ‘n’ drop migration. It also handles stuff like the network-based storage (using NFS), a library of images for creating new virtual machines, and Physical To Virtual conversions to migrate existing servers to Xen. I’m not on the management apps side of things, but there are plans for more cool XenOptimizer features in the future.
The XenSource business model is actually kinda interesting. Basically, if everyone uses Xen as their hypervisor because it’s high performance, flexible and free, then that *creates* a large market for management tools, training, support. This market will then have multiple of competing entities, avoiding (some) lock in and keeping prices and feature-sets competitive. The idea is that XenSource will be sufficiently good at Xen-related stuff to get a big slice of that market 🙂
I work for a company that rents out virtual servers and we use Xen. I can’t really say a bad thing about it, it really is a great solution!
Thanks for Xen!
Edited 2006-01-20 13:43
Does live migration works across different endianness? I have no idea how much the hypervisor takes into its hands when it comes to virtualization, but would it be possible to eg. move a NetBSD kernel from i386 to PPC? What about 32bit/64bit architectures?
You can’t migrate across different instruction sets directly, because the guest OS runs directly on the hardware. This also implies you can’t migrate across archs with a different native endianness. To run the same OS on different archs, use QEmu, but this can’t live migrate (although you could probably get it to stop the VM, save the state, and then copy that state to the destination host and resume).
Currently, 64-bit Xen will only run 64-bit Xen-aware guests (except under full virtualisation, assisted by Intel VT / AMD Pacifica hardware), so you have to migrate like-to-like. Full virtualisation will run 32-bit unmodified guests on a 64-bit host, so once migration is implemented for fully virtualised guests it may well be possible to migrate a 32-bit guest to a 64-bit host.
Does that answer your questions?
Yes it does
Thanks for your swift reply, btw! I look forward to testing Xen on NetBSD…
NetBSD 3.0 has dom0 (host) and domU (guest) support for Xen 2.0 systems. It hasn’t been ported to Xen 3.0 yet, but once that happens it should be forwards compatible with future Xen systems for years (the 3.0 interface is supposed to be the one we stick with into the future).
FreeBSD is getting native support for Xen (i.e. included in an official FreeBSD release) soon. Linux will be getting a Xen patch soon also, and major distros (e.g. SuSE, RedHat) seem to be becoming “Xen native”. Hopefully by later this year, there’ll be a good selection of Linux and BSD distros that run “natively” on Xen, as both host and guest.
is there a way to run windows now?
xensource.com’s propaganda papers says it is possible, FAQ on their pages says it is not currently possible.
are there processors with VT technology availaible now? how do I know if the processor is able to run windows under xen?
i have used xen with debian before, I just need to have one windows machine in datacenter and I’m considering this….
Yes, Windows runs on Xen on VT hardware. There’s a port to Pacifica too but I can’t remember if it’s been merged into the mainline yet.
From what I hear, VT mode is currently not quite as fast / robust / full-featured as “Xen-native” mode just yet. It does run Windows test suites stably during Intel’s regular testing, and it apparently has reasonable performance so long as you’re not doing anything graphics intensive. You may find it is adequate for your needs, but you can expect it to get a lot better during this year. I do know of at least one user who has managed to buy VT hardware and is using it to run Windows.
There’s a lot of optimisation planned to get VT mode performance as good as possible and to give it features like suspend/resume and live migration (which already work for Xen-aware guests).