Monday, March 14, 2005

Xen and the Art of Virtual Maintenance!

I have always been inspired by VMware. The fact that it was started by an OS professor (Mendel Rosenblum of Stanford) was part of the halo. Then it got bought by EMC and some of the allure vanished. When Microsoft bought VirtualPC instead of VMware it appeared that the latter was doomed. EMC purchase made millionaires at VMware (I guess) while taking EMC stock down!

It seemed that the X86 chip virtualization market was pretty much sewn up by these two. IBM always held the big advantage in virtual machines back from their mainframe days. It appeared that there wasn't much scope for innovation, despite VMware's attempts to crack new markets like testing, sand-boxing, etc.

Then came Xen, an offering from another university - Cambridge. In the LinuxWorld that happened in Boston recently, Xen got endorsements from a lot of big names. Along with that came the news of a new company XenSource which has been trying to productize Xen. The founders of XenSource claim to be the originators of Xen so they have the credibility that is needed to get enterprise customers to sign up. Xen is released under GPL, so it is likely that XenSource is following the foot-steps of Cygnus - the commercial arm of GNU which was later bought by Red Hat.

There is some information available on Xen already:
Xen requires the operating systems to be modified to work. That's why most implementations of Xen today are with Linux variants (most 2.4 and 2.6 kernel based variants are supported), and that's why they have issues with porting to Windows. VMware is of course ahead of the game here. But Xen technology also enables it to be ported more easily to other OS's. Paravirtualization improves performance and companies like Novell have decided to go for Xen over user level Linux for similar reasons.

Also, any work done for a specific OS while working with Xen interfaces is not covered by GPL and is thus not bound by it. Good news for any company that wants to add to the project and also make some money by retaining IP. This also helps a project like Apache whose licenses are far more liberal than GPL.

It would be interesting to see if XenSource is able to get revenue like JBoss has, or if it finds other rivals emerging because of the lower (by definition) barrier to entry typically found in open source based organizations.

But in any case, this technology may finally provide utility computing which has been promised for a while now.