Update: The conversation continues HERE.

With Linux in the Enterprise, RHEL is king. Sure there are people who love and use Debian, or Suse. I would imagine that if you looked hard enough you could likely find somebody who’s using Slackware or Gentoo in a business somewhere. But I think it can safely be said that RHEL is currently the dominant enterprise Linux distribution. Then, of course, there are the clones.  If you so choose, you can forgo Shadowman’s Support team and either compile the freely available Redhat Source RPMs, or choose to use a community-supported RHEL clone. Currently, the two most popular of those clone distributions are CEntOS (Community Enterprise Operating System) and Scientific Linux (SL).

So if you have decided to not utilize Redhat support, which of these downstream clones is the better choice? With the recent (much delayed) release of CentOS 6.0 in the past week, many companies are looking to move up to the RHEL 6.0 family of operating systems. But is CentOS still the right choice? Being a primarily CentOS shop, and being more than a little OCD myself, I decided to compare the two in as practical as a manner as I could. Below are the results.


When it’s running on production, you don’t have time to wait on a tiny community to figure out how to backport in some obscure cross-site scripting vulnerability in an even more obscure module in your favorite language, even if you’re part of that community. An enterprise operating system needs to have an active and robust community to support itself, paid or not.

CentOS has been around for a long time and has a huge following. There have been murmurs of late about the core contributors getting tired, and the delay in CentOS 6.0 was the evidence. I don’t believe that fully, but I do believe the project could do with some fresh blood and possibly some new ideas.  But I don’t think it’s going anywhere anytime soon.

Scientific Linux hasn’t been around nearly as long, at least on the scale that it is currently enjoying. The community, however, is vibrant, and is backed by several large research labs such as CERN and Fermilab. Big plusses.

Advantage: Push


In Open Source software, the process is often times as important as the product. While I don’t believe there is anything massively different in how these 2 projects are doing what the do, SL is certainly better at talking about it and making the community aware of how it’s working. This presentation(PDF) is a pretty great one, even if it’s a little dated. SL Community, I’d love to see an update, for the record.

Advantage: Scientific Linux

RHEL Compatability:

This used to be a much larger difference, as late as version 5.x. Scientific made some pretty large changes to the RHEL repository structure, and added in some packages of their own. CentOS has always been as faithful a clone as was possible at the time. This is largely cleaned up in version 6.0, with the extra SL packages moving out to external repos, but much like the workflow advantage above, perception is still a strong influence.

Why is this important? Well, like lots of people, we’re a mixed RHEL/CentOS shop. It just makes life SO MUCH EASIER.

Advantage: CentOS

Mirror Speed and Availability:

I couldn’t find any perceivable difference in this category. Both networks are robust and highly available.

Advantage: Push

Community Support:

This is one of the most important factors when adopting a distribution, and sadly the one answer I’m not able to fully answer. I utilize CentOS support all the time, via the web, forums, and IRC. I’ve only occasionally sought support for SL, and this was way back in version 5.2. So I’m not really qualified to answer this one fully right now. However, I see active forums off of their home page and a 10 minute visit to the IRC channel on freenode saw plenty of conversation for a Tuesday night. I don’t think SL would have grown so much without good community support.

Advantage: Push

Lifecycle Support:

This was the one that surprised me.

As expected, CentOS mirrors the RHEL lifecycles. RHEL/CentOS 5.x will be supported through 2014. They haven’t updated their wiki yet, but I’m sure 6.x will be the same, with a full 7-year lifecycle.

Scientific only plans on a three year lifecycle. But on their forums they also mention supporting things in theory as long as Redhat does. So I’m a little confused on this one.

While I don’t typically plan on using the same OS for longer than 3 years, if it ain’t broke, I’m certainly not fixing it.

Advantage: CentOS

So those are my thoughts on the situation. Scientific Linux is definitely on the rise, and CentOS certainly needs to air out themselves a little. But at least with version 6.0, we’re still going to be going with our tried and true CentOS. I’m just not comfortable enough, yet, with the Scientific Linux community, mainly because they still don’t quite know how long they plan to keep their products alive. Out of this look at RHEL clones, though, the single biggest thing I’ve discovered is that I’m going to have to keep evaluating this choice down the road.