Jan 31, 2007

Before we go anywhere, I wanted to say that I hard a hard time writing this article. The reason I say this is because CentOS and RHEL are essentially the same thing. Both distro’s use the same binary package format (RPM). Both use the same kernel version (I briefly discuss what a kernel is below). Both use the same versions of critical system packages
including glibc, zlib, openssl, coreutils, which are coincidentally free software that can be downloaded, built, and distributed as RPM’s by anyone compelled to do so. Really the only big difference is the mandatory support bundled with RHEL.

linux dedicated servers

Supported users of RHEL can use the provided up2date application to install, and/or upgrade different RPM packages, including the kernel. Supported users also receive membership to the “RedHat Network”. The RHN compliments up2date by providing user’s with priority update email notifications, errata, and an automatic update facility. CentOS users also have a similar application called “yum”, which is detailed below. Depending on the level of support included with your RHEL purchase you are entitled to phone, and or web-based/email support.

CentOS does not provide any “official” support. However, there are many (archived) mailing-list and forum posts that share the same knowledge for free. Granted, it may take slightly longer to find the answer if you are the one actually posting to a list with your issue. This is exactly why we provide our own support services (for a nominal fee). One of our
skilled server administrator’s can login to your server, resolve the issue, and then show you the steps taken to fix the problem, were it ever to recur. I was not able to find a figure for RedHat’s support time-to-resolution, however they do guarantee time-to-respond (depending on the level of support you have). We guarantee a time-to-respond of 1 hour or less and our time-to-resolution via our support portal, on average, is slightly more than 1 hour.

CentOS does provide “supported” updates. Not because CentOS officially supports them, but because they are supported (tested/proven stable/secure) with the distribution’s base and committed as stable. Instead of ‘up2date’, ‘yum’ is used with CentOS. In the end, both of the package management systems complete the same upgrades. Actually, it strikes us as funny, because both package managers install the same RPM’s, the exact same versions, built with the same compilers, with the same tree of dependencies. For those who do not already know, RPM is the RedHat package management system, which is similar to an .msi installer in windows.

In addition to our General Management Package, SingleHop also offers kernel and OS updates. It’s true that we do use the package manager to update the applications included with the operating system, but we install a custom kernel with additional security and scalability features to every server. Also, we are very attentive to the security community, so as soon as a new vulnerability is discovered, we are ready with a workaround and/or patch.

Speaking of kernels, now is a better time than ever to explain what a kernel consists of and to denote the differences between the CentOS and RedHat kernels. A kernel or an operating system kernel, is the interface between software and hardware. The kernel is also responsible for managing process scheduler and TCP/IP stack. If you don’t want that
means, imagine your car without the engine. The kernel used in CentOS is identical to the kernel used in RHEL; both are based on the 2.6.9 tree and are heavily patched. The Linux kernel is released under the GPL (GNU Project General Public License), so RedHat is required by the terms of the GPL to release any modifications that they make to the kernel source to the open source community.

At Single Hop we are more than capable of supporting RHEL, CentOS, Debian, Fedora, FreeBSD, Gentoo, SuSE, or even Slackware. We specifically recommend CentOS for a few different reasons. Of these, the main reason is consistency. Nearly 90% of our Linux servers are currently running CentOS. Using the same distribution allows us to test updates on staging servers before applying them to your production machine. CentOS also functions perfectly with cPanel, which is our recommended hosting control panel.

Hopefully the article above answers your questions on the differences between the two operating systems. If you have any questions or would like to discuss this issue further, please feel free to contact us at contact@singlehop.com!

Comments

    More confusing than enlightening. At the end of it, all that is clear is a sales pitch by Single-hop.

    As a regular user of RedHat and Fedora, to me it always makes sense to buy support “from the horse’s mouth”. As you say CentOS is “supported” by online forum and mail-lists. Fedora is supported pretty much the same way. If I were happy with this kind of support, pretty much any GNU/Linux system out there would fit the bill. And there are deployments that fit this requirement.

    If, on the other hand, I needed enterprise scale support and – more importantly – core application certification, I’d go with Red Hat 100% of the time.

    Thats my opinion though – anyone else is entitled to their own opinions and choices. That, in the end, is the best thing about FLOSS.

    Posted by G Fernandes on February 2, 2007 Reply

    There is a reason that RHEL and CentOS have the same packages. They are the same product, minus the proprietary Redhat pieces and non GPL pieces that are not legally available for free. CentOS takes the GPL portions and repackages them as CentOS.

    Posted by Marty on February 2, 2007 Reply

    I agree with G. Fernandes. This is just a fluff piece for Single-hop. The difference between CentOS and RHEL doesn’t need a whole write up like above. It goes like this:

    CentOS is built from the same sources as RHEL, the difference is that CentOS does not have paid support behind it.

    Btw, you can use up2date with CentOS also, it is just faster to use the command-line yum tool.

    Posted by mookie on February 2, 2007 Reply

    This article was exactly what I was looking for. It is nice that the article spent some time to clearly define support. I think many people are stuck between Fedora Core / Cent OS / RedHat EL. Everyone wants RedHat EL because no one wants a development branch FC5 or a knock off (Cent OS). However if you can get a knock off (Cent OS) and get the same thing as the original for a better price (free) that is a strong argument for the Knock Off.

    Posted by Edward Capriolo on May 29, 2007 Reply

    Thanks for the good article on linux dedicated servers, and centos / cent os.

    Posted by John on October 9, 2007 Reply

    Then why not go with Fedora 7 instead?

    Posted by Andrew on October 11, 2007 Reply

    … and reformat and go through dependency hell every 6 months? No thanks.

    I’m still using CentOS 4 and like it just fine 1.5 years later thank you very much.

    When will I upgrade? I dunno. Don’t care.

    Posted by p.e.alvarez on December 1, 2007 Reply

    Fedora is OK but it’s NOT Red Hat. It’s built different. I used CentOS as a learning tool when I was studying for my RCHE…well I passed and now am working as a Sys Admin…with RHEL…I guess CentOS paid off for them there :-)

    -C

    Posted by custangro on March 2, 2008 Reply

    Edward, I don’t think “knock off” is a good term for CentOS, if you took a Mercedes, removed the logos and replaced them with a generic C for car, it’d still be a mercedes. CentOS is just the same as if you took the trouble to install RedHat then remove all the logos and RedHat specific code.

    What I don’t think this article addressed and what I was looking for is a practical judgment of the difference. I myself find that calling RedHat support gets me the answer less often and slower than “Googling” for it, and if it’s a real tough one trolling the forums. We have RedHat support and also use Ubuntu for non production servers, It’s been my experience that my time to resolution is way faster on Ubuntu than RedHat despite the lack of paid for support.

    Posted by Greg on October 9, 2009 Reply

    Informative – nicely written and structured. I always considered this to be the exact difference, and that is the cost factor. I too, have RH Certs, and work as a Sys Admin, on a conglomerate of OS’s, I choose CentOS, because by far, hands down (IMHO), its the greatest supported release available. and yes, I have used other releases.

    Regards,
    DosDawg

    Posted by TerabyteHosting on January 7, 2010 Reply

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