In an effort to save on licensing costs I have just completed the migration from SLES to OpenSUSE. I have to say it was a little unnerving to step away from an enterprise class distribution. There were so many choices when it came to choosing the replacement for SLES, I knew we no longer wished to pay the licensing fee’s to only have access to software updates and support that has never been used (IMHO google for me is the best support agreement).
On the cards were CentOS, Ubuntu LTS, and OpenSUSE. Our main requirements were the ability to access upgrades and the use of an auto build system for rapid deployment. CentOS was ruled out early in the piece (unfortunately I have to say only for petty reasons, none of which are worth listing here). So the competition was between Ubuntu and OpenSUSE, now my personal opinion here would be for Ubuntu to be the successor but unfortunately it had a few fatal flaws.
The main positive for Ubuntu was the 5 year life cycle for Ubuntu LTS releases, 8.04 was the last so that gave me 4 years of supported updates. Also the Debian pedegree tied with the ideology of ease of usability. The only real subtractor was the Ubuntu auto build facilities. They just plain failed to function, I followed the directions laid out somewhere in the Ubuntu help pages but the installation of the required components failed. It was just plain clunky and immature, hopefully in time it will get there.
OpenSUSE had the smallest amount of change required for implementation. Almost all of the existing system documentation was still relevant between SLES and OpenSUSE including all custom scripts and applications just slid into place and worked out of the box. Autoyast was also a big massive tick in its favour, we had already been using the autoinstall system for our SLES setup. The only downside to choosing OpenSUSE was the short life cycle. Each OpenSUSE release will only support updates for two years at which point the move to the latest version will be required (either that or go through the process of selecting a new distribution again).
A couple of application compatibility issues surrounding going through two major application changes, those being PHP 5.1 to 5.2 and PostgreSQL from 8.1 to 8.3 but all issues were relatively simple to fix as our applications are developed in house. In summary, the migration has been a complete success and has been relatively painless, there were no real gotchas.