Most probably you have already decided to use Linux as your server operating system as did 98% of the Top 500 supercomputers (Based on performance). Obviously Linux is usually the preferred choice for most of servers, so I will not discuss this point further.
But which flavor are you going to use?
Some are supported by robust company with professional support such as Suse, RedHat, etc…. and some are community driven (Ubuntu, Debian, Fedora, …).
For me, what I value the most in a server distribution are:
1) Community Support:
I expect to use a popular distribution where I can be sure most of the problems I will be facing if any, would have been already asked by someone else. Or if not, have proper forums to ask questions.
I want to make sure the services I will install are stable enough for a server. Not too new, not too old.
Well, if any breach, backdoors, etc…is detected, I expect the devs of the distribution to release a patch rapidly. But also, the distribution must be popular enough and security oriented in their processes.
4) Large choice of services already pre-configured for this distribution.
I love when it works out of the box with no further configuration to do and I’m avoid too time consuming distributions.
Based on these criteria, basically, I prioritize 3 distributions, although the others are great too depending on your needs and skills:
But as I’m used to Debian/Ubuntu style (Most popular distribution), I usually only work with these 2 for servers.
The issue I have with Debian is it’s too old packages in the Stable version. However, after run my server on Ubuntu for 2 years and switch to Debian afterwards, I can clearly feel the difference in the stability of the system.
Debian is smoother and I encounter less issues with it. But I dislike the fact to split the Debian version in Stable, Testing, Unstable, Experimental. Always annoying to play with the source.list or preferences to select the version I want. (Gentoo was easier in that sense…but way too time consuming).
Anyway, there is no secret. Stability often means intensively tested, meaning you may have “outdated” versions if you only use Stable repository. I’m now used to install first the Stable version and only if I want to have a specific software updated, I’ll use backport or testing repositories to install it. I actually don’t need to have the latest PHP or MySQL version if the new features are not essential for me. But for application like Deluge-torrent, etc.. I do want a more recent version if possible to enjoy latest GUI, performance, .. improvements.
That is why Debian has started to be my favorite distribution for server and I strongly advice you to use it too as it is not more difficult than Ubuntu actually.
Sysadmin & Uptime