Red Hat Enterprise Linux (RHEL) is reliable, easy to use, and has extensive support options. One thing it is not, though, is inexpensive. The usual alternative for people who can't or won't use RHEL is its publicly available development edition, Fedora Core. Unfortunately, Fedora is too often littered with showstopping bugs, and doesn't make as reliable a platform as RHEL does. That's where CentOS comes in -- it's built from the source RPMs from RHEL Advanced Server, minus Red Hat's trademarks and proprietary graphics. The end result is an operating system that operates and performs identically to RHEL, with a few extra tools to make it easier to update, and no official Red Hat logos or images.
CentOS is an acronym for Community ENTerprise Operating System, meaning it is a free-of-charge and free-as-in-rights operating system that is stable and reliable enough to be used in a large business. The release cycle is slow and predictable, which is favorable to large businesses that seek a stable, uniform operating environment with rapid security update delivery. Home desktop users may not find as much enjoyment in CentOS because its desktop software tends to be a few versions older than the latest and greatest packages included in home desktop-oriented GNU/Linux distributions.
CentOS has a relatively simple installation routine, just like Red Hat Enterprise Linux. Unlike RHEL, which has different editions for a variety of business uses, CentOS only maintains one core from which you can customize your operating environment to act as a desktop, workstation, or server. RHEL has the same options, but is packaged and supported differently for different uses.
The GNOME desktop environment as customized for CentOS is easy to use, navigate, and customize. It includes up2date, a program that notifies you of software updates, though the preferred method of software maintenance in CentOS is through YUM (Yellowdog Updater, Modified). YUM requires command line interaction, but the only command most sysadmins need to know is
yum update -- a simple command, to say the least.
CentOS comes with a large enough selection of desktop and server software that the computing needs of nearly any business or professional operation can be met. Anything certified for RHEL should work with CentOS. If you don't find what you want, you can use the Dag Wieers RPM repository to add many more packages to your system.
System services can be enabled, disabled, or restarted through a nice graphical tool; a similarly easy-to-use tool exists for connecting to other servers on the network. Ease of service configuration ends there, though -- each service must be custom-configured by hand from a text editor. The config files are generally well-commented and do not significantly deviate from the universal default values or file names.
What's new in 4.3
|CentOS: RHEL rebranded|
Putting it to the test
I had some trouble with the x86 version of CentOS 4.3 on an AMD Athlon 64 X2 test system. Specifically, the USB keyboard and mouse went totally crazy -- repeating keys and clicks, and in general being unusable. Oddly, the problem did not occur in the 64-bit edition of the same release.
The up2date program is still there, but it won't be as fast because of the new server selection scheme employed by YUM. On my test system, the
yum update method worked quickly and without error. up2date, however, crashed several times on the AMD64 version, and took a long time to complete on the x86 edition.
The software is somewhat aged, but that's to be expected from a maintenance release, which is what 4.3 is.
A few people have written to me post-publication and asked that I mention YUMEX, a graphical frontend for YUM. It can of course be installed via YUM:
yum install yumex. It's a nice utility, and definitely a great addition to CentOS. However, I still feel that it should supercede up2date, or that the user should have the option of using YUM instead of up2date for updates by default, not as an add-on or afterthought.
Conclusions and developer recommendations
CentOS is the perfect alternative for people who can't afford or otherwise are opposed to paying for Red Hat Enterprise Linux. It's as perfect a clone of RHEL Advanced Server 4 Update 3 as can legally be distributed. Overall I found it just as easy to install, use, and maintain as RHEL4.
The only recommendation I have is for the CentOS team to make YUM graphical in a minimalist way, much like up2date currently is. The beauty of up2date is that it is so easy to use and understand, whereas running YUM from the command line to update the system by hand is sloppy and unreliable. I'd like to see an up2date-like utility that monitors the update servers for changes and either automatically applies them, or puts up a big red exclamation mark like up2date does.
|Manufacturer||The CentOS Project|
|Architectures||x86, AMD64/EM64T, IA64, PPC, Alpha, SPARC, S390, and S390x|
|License||GNU General Public License|
|Market||Servers, workstations, and desktops of all kinds; people who like Red Hat Enterprise Linux but can't afford it|
|Price (retail)||Free of charge|
|Previous version||CentOS 4.2|
|Product Web site||Click here|