That Red Hat is awfully expensive!

May 20, 2009 3:01 PM

Is paying for a RHEL subscription worth it, or should we just go with CentOS?

We're looking at moving our e-mail server to more-capable hardware, and would like to avoid paying $4k+ for a new Xserve, if at all possible. We're reasonably happy with our current package, Communigate, but it's severely hardware constrained now.

The only two applications that need to run on it are Communigate (which has ports for every OS under the sun) and Retrospect (our backup client, which has a Red Hat rpm).

Ideally, I'd get a cheap Quad-Core server from Dell, slap CentOS on it, installed our two applications, and call it a day. Still, I have nagging questions. Is paying for RHEL worth it? Can you continue updating your OS after your subscription expires? Is CentOS really 100% binary compatible with Red Hat?

posted by Oktober to computers & internet (10 comments total)

For one server, standalone, I would probably just go with CentOS over a RHEL subscription (in a field of those two choices, anyway).

CentOS, being compiled from the Red Hat sources, should be just fine for your needs (and the security updates and whatnot are free). It is "100% binary compatible" in the sense that, since it is compiled from the same source, using roughly the same build environment, and for the same target architectures, you can reasonably expect any linux binary to function under CentOS as it would under RHEL.

You might run in to dependency problems when installing your third-party rpms, but as long as they were built with reasonably-sane defaults, I don't foresee installation being too much of an issue.

You may also want to consider using CentOS's provided versions of postfix and dovecot over communigate, but that's probably the subject for another askme.
posted by namewithoutwords at 4:10 PM on May 20

I've used CentOS for a couple of years now in our production environment and found absolutely no operational difference from RHEL. When people ask me this question at the day job regarding what OS they want to run, I ask them two questions:

1) Do you ever foresee a need to talk to the OS vendor directly for support?
2) Do you ever foresee a need to sue the OS vendor?

If the answer to both is no, I tell them to use CentOS. If they answer Yes to one or more, RHEL.
posted by barc0001 at 4:14 PM on May 20

I suppose I should also point out that only once has anyone answered yes, and that was to them thinking they might want to talk to the OS vendor directly for support. In reality, all it has done is make someone at their company sleep better, since it's over a year in on that box and no problem has cropped up with the OS at all, let alone one requiring a call to Red Hat.
posted by barc0001 at 4:16 PM on May 20

IDNCMOK* but:
Is paying for RHEL worth it? Can you continue updating your OS after your subscription expires?
No, and no. Although RH is distressingly confusing when it comes to subscriptions, entitlements, and whatnot. The RHN website is a complete, total, and utter mess. But once your "entitlement" has expired, you're SOL when it comes to updates.
Theoretically, if you have a single entitled system, you could possibly shift the entitlement around to the various RH boxes you have, in order to update them.
But that'd surely be counter to the terms of service. Or something.

Is CentOS really 100% binary compatible with Red Hat?
So far, it definitely seems to be! My company has been deploying CentOS-based servers for a few years now, and haven't come across any binary incompatibilities. RPMs JustWork(tm). "yum" is great as a package manager (I even prefer it to apt). So yes -- I don't see any reason why not to give it a shot.

In fact, could you run up a test box on some spare hardware (or a VM?) and see if it works with your required programs? Testing's always good, and this way you can confirm for yourself whether it works or not......

*I Do Not Compile My Own Kernel
posted by coriolisdave at 4:18 PM on May 20

If you want a complex, large-scale environment where you need to automate the management of many servers, and are running novel or bespoke apps on novel hardware, then, sure RHEL subs make sense. You may well need the vendor attention, to cosider Satellite, and so on.

For a few simple servers you're comfortable supporting, CentOS will be fine.
posted by rodgerd at 6:02 PM on May 20

Wow

Thanks guys. I'm a relatively newly minted Linux admin (have been running Ubuntu at home for a while, got my job to pay for the O'Reilly School courses, etc) so this is mostly just me covering all of my bases before I deploy something in production. I fully intend on building a test box on some random hardware and testing both apps before I purchase anything.

PS - I'd be fine using postfix/dovecot, but part of our requirements are that it can be administered by other IT staff while I'm out, which makes a web front end pretty much required.
posted by Oktober at 6:14 PM on May 20

I've had good luck with RHEL support. If you need help setting things up or fixing things, they can be handy. If you need to Cover Your Ass, it also comes in handy because problems can be passed along to their support staff. I use CentOS for my own website though (see profile), and I've never run into any problems, and use yum for pretty much everything with great success.

I also agree with namewithoutwords though, postfix/dovecot are well tested and capable of handling anything you throw at it. cyrus is also a bit bulky, but good in its own way. I'm a unix engineer by trade and I've never heard of communigate. I also run several high-traffic mail servers.
posted by Mach5 at 6:19 PM on May 20

One thing that RHEL support comes with that's pretty neat is the redhat network. There's work to develop an open source alternative

But if you're considering going it alone, the question becomes why you need RHEL at all. Debian and friends offer a nice mix of software, support and tools. You mention that retrospect comes in an RPM; Debian has a tool alien for that. However, I'm vastly confused as EMC's website doesn't seem to be aware there's a Linux offering. Nevertheless, this page quoth:

Talking to one of our engineers, he suggested "Debian or Ubuntu users can use a tool called "alien" to create a debian package from the rpm". This has worked for at least one customer. See newer posts within this thread.

posted by pwnguin at 8:40 PM on May 20

err, an open source alternative to their RNH satellite called Spacewalk.
posted by pwnguin at 8:41 PM on May 20

It's worth noting that you can convert a RH system to CentOS. According to a friend, the steps are
"download centos-release and centos-release-notes
rpm -ev redhat-release*
install the centos release rpms
Then do a yum clean all and yum update"
posted by PueExMachina at 8:58 PM on May 20