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Desperately Seeking Xen
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."
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
20 Dell 1955 Blades; 16G ram; 70GB SAS 10K drive (one) on which ESX 3.0 is hosted (or a variety of Xen flavors); four gigabit ethernet controllers per blade; CISCO 4948 48 port switch, with 4 ethernets per blade bonded; CISCO 6504e core with Sup-32; Net App 3020 and 3050 for NFS and iSCSI; some EMC Clarion units, likewise.
For CPU we used SPEC CPU 2006 and score about 5-6ish % on VMWare as the same test done on those blades in hard metal. Xen is undiscernably different to the subjective eye than hard metal. I would have to break out large batch testing methodology and run the results through inferential statistics to conclude that there was a difference at all.
I/O is a different story.
The Xen performance claims and the VZ performance claims aren't really useful. They're theoretical. As in, "theoretically, we can stack 100 operating systems on this blade efficiently." Think about that. That's just plain nuts. I can't think of a real use case for that.
BTW, if you like OpenVZ, and have the right use case, the commercial Virtuozzo product ranks as the "best virtualization technology that no one has ever heard of" in my book. They really have their IT management story down pat.
C//