Vita Rara: A Life Uncommon

New Server - A Little Xen

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The past week has been a trial by fire. We purchased a new server to handle hosting sites, email, clients, etc. Dual quad core Xeon, 16GB RAM and lots of drive space. This machine was too much to waste on a single installation of Linux so I decided it was time to learn virtualization and Xen in particular.

Xen is a hypervisor that makes it possible to run multiple operating systems on one machine as though it were multiple machines. Basically it allows you to make one computer look like a whole bunch of computers. Each "computer" can even run a different operating system.

I originally was going to use Xen's support for Intel's VT technology to use full hardware virtualization, but after a week of going down that path I decided it really wasn't ready for prime time. So, I punted and am now using Xen's paravirtualization. At this point if you're looking at Xen I'd stick with paravirtualization if your environment is mostly Linux.

Paravirtualization is an interesting technology and provides almost native hardware speeds to the guest operating systems running on the server, while being isolated from each other. It also allows the hypervisor to perform some serious optimizations because the kernel running the guest operating systems know they are running in a virtualized environment.

You should notice that the site is much much faster. Previously this site was running a Pentium II 300MHz machine with 384MB RAM. We were really pushing the hardware to perform tasks it really wasn't spec'ed for.

Some articles and resources that helped me with Xen:

  • A great source for Xen ready disk images.
  • The Xen Wiki: An invaluable store of Xen knowledge. Some of the information needs to be brought up to date, but it can still save your bacon.
  • The Xen-users Mailing List Archive: The search feature is invaluable. When you get stuck, search here, the answer is likely in there.