The Machine within the Machine

Although Virtual Machines are widespread across CERN, you probably won't have heard of them unless you work for an experiment. Virtual machines - known as VMs - allow you to create a separate machine within your own, allowing you to run Linux on your Mac, or Windows on your Linux - whatever combination you need.


Using a CERN Virtual Machine, a Linux analysis software runs on a Macbook.

When it comes to LHC data, one of the primary issues collaborations face is the diversity of computing environments among collaborators spread across the world. What if an institute cannot run the analysis software because they use different operating systems?

"That's where the CernVM project comes in," says Gerardo Ganis, PH-SFT staff member and leader of the CernVM project. "We were able to respond to experimentalists' concerns by providing a virtual machine package that could be used to run experiment software. This way, no matter what hardware they have to hand, they're still able to do their job."

Seems like a simple solution, right? Not quite. "Although virtualisation has been around many years, there had always been too many performance issues," explains Jakob Blomer, PH-SFT fellow, author and main developer of the CernVM file system. "But with the recent advances in virtualisation technology on personal computing systems, using a virtual machine can be easily done."

The CernVM team also stumbled upon a whole new way to help experiments with their IT needs: as well as providing a single platform for experimentalists, they could deliver the latest experimental software through a file system online.

With new experimental analysis software being released every other day, it can be tough for users to keep up. "We created the CernVM file system, which keeps up with the latest software so users don't have to," says Blomer. "This system provides new experimental software for download. It's a win-win: we only have to send out a small, easy-to-distribute virtual machine, and users will receive automatic updates of their software from CERN." Not only does this system ensure that all LHC experiments are running their software on the right systems, it also gives developers the freedom to focus their developments on one virtual machine platform.

With CERN's experiments having already embraced virtualisation, the best is yet to come with last year seeing the “virtualising” of the entire CERN infrastructure. Expect to hear more about the potential of virtualisation, starting with an upcoming Bulletin article exploring how VMs are being used to save endangered data and software environments.

by Katarina Anthony