virtually speaking

I’ve gotten very interested in virtualization technology recently. There’s a high probability I will be working with VMware this summer, and several of my websites (including this one) run on a virtual private server provided by Tektonic, running CentOS 3 through Virtuozzo.

Virtualization is a fascinating concept. Instead of needing gobs of physical servers, by running operating systems through a virtualization layer, several servers can be run off one physical piece of hardware. With several options available – including Xen, VMware, Virtuozzo, User-Mode Linux, Virtual Server – deciding on a particular route is difficult at best. Depending on your budget, actual server OS requirements, and available physical hardware, all of the above may end up being viable options.

Because several guest operating systems will be running inside or on top of the host virtualizer, underlying hardware generally has to be pretty hefty. However, some of the available virtualization options will allow as many as 100 guest operating environments – so installing just a few high-end servers can replace potentially dozens or hundreds of pieces of hardware.

Solutions such as the new edition of VMware ESX Server are actually smart enough to automatically shift virtual instances from one piece of physical hardware to another based on server load, or in the event of hardware problems.

User-Mode Linux, aka UML, is actually Linux ported to run on an abstract hardware standard implemented in Linux – so it’s Linux ported to run on itself. Now that hurts to think about.

As I get more personal experience with virtualization technology, I’m sure I’ll be writing more about it.