Although Red Hat Linux is available in its basic form as a free product (which was recently split out into the new Fedora Project, there are some commercial versions of the product as well – imaginatively named Red Hat Enterprise Linux ("RHEL"). The Enterprise versions, as you'd expect, have extra features that you don't find in the freeware version. First off, there's support for platforms other than the plain old Intel x86 range, support for up to 64GB of internal RAM, a built-in secure Web server (which was an option with the previous version of Red Hat Enterprise) and support for booting diskless client computers. RHEL comes in three flavours: "WS" ("Workstation") is for commercial desktops; "ES" ("Entry/mid Server") is for low- and mid-range servers, and at the top end is "AS" (Advanced Server) for high-end servers. The WS edition runs on x86 and 64-bit Intel and AMD processors, and as you'd expect it includes things like desktop applications but not server-type packages such as DHCP and DNS servers. Of the two server versions, we were a little surprised to see that ES supports only x86 processors, though you do get the addition of the obvious server applications (DNS, RADIUS, the Apache Web server, the Amanda backup server, etc). It's only with the AS flavour of the server product (the one we looked at) that you get support for up to eight processors in an SMP configuration and 64GB memory – not to mention the ability to run on things like the System/360, Itanium or AMD64 CPUs. It struck us as strange that the WS edition is also able to break the 8GB RAM barrier (albeit with only one or two CPUs), but this is because Red Hat markets the WS edition for use in high-performance parallel-computing systems, where you have a large collection of motherboards mounted in close proximity and connected at high speeds, for performing specialist processing tasks. Although shipping of boxed products was taking some time when we asked for our review copy, RHEL can be delivered over the Internet. Because we already had Linux systems that we keep current via Red Hat's update Web site, getting access to downloadable versions of RHEL was just a case of the company supplying a registration code, us typing it into the site, and selecting the new product that had magically appeared on the list. The download comes in three sets: a four-disc set holding the installable Linux package itself; a three-disc set with the source code for the system; and a two-disc documentation set. Of the latter, one disc relates to Europe and the other to non-Europe countries, so we only bothered with the four-disc installer set and the Europe-oriented documentation CD. The downloads are all ISO CD images, so we used our resident Windows PC and Roxio EasyCD Creator to burn a handful of recordable CDs. Installation
Installation of the Enterprise version is little different from that with the freeware version. The installer is graphical and wizard-based, and it's a very simple job of defining your disk partitions (or choosing "auto-partition" if you don't have extravagant requirements), selecting which software packages to install (you can pick individual server components such as databases, DNS, Windows file sharing, network file services, and so on, or you can do what we did and choose "everything") and hitting "Go". On our 1GHz Pentium-III test server the process of copying files took about 45 minutes, with the system prompting us to swap CDs from time to time. When the main installation had finished, you're asked to configure the X-Windows graphical user interface; this can be a bit fiddly but if your equipment is reasonably old then nine times out of ten it'll auto-detect your graphics card and monitor type. The GUI desktop looks rather like the one with the basic Red Hat product, with a few additional gizmos. There are plenty of graphical configuration tools for the various key server applications, such as the DNS (traditionally a pain to configure via text files), Samba (Windows file sharing), HTTP (Web) server and NFS file sharing systems – though this is in no way different from the freeware version, which gives you precisely the same tools if you select the "server" or "everything" options at install time. Integration with directory services using LDAP is also handled via a nice GUI interface, although you can choose to use Unix-type directory services such as NIS if you so desire. Add-ons
RHEL's download site has a few add-ons for the system that you can download either as individual packages or on a CD image. There are only a couple of dozen at the time of writing, including Red Hat-specific versions of the MySQL and PostgreSQL database systems and various Java runtime packages and development tools (the Eclipse IDE that's becoming increasingly popular at the moment). So just what does RHEL give you that the freeware version doesn't? In short, the stuff that many organisations need: stability and support. Whereas the freeware version (now distributed under the Fedora banner) is updated with great regularity and can be considered "bleeding edge", you get guarantees with the Enterprise version that new versions will be less frequent but tested to death; not only this, but you get the guarantee that the current version will be officially supported for at least five years, which can't be said about the free version. Then there's application support: the high-end commercial applications produced by big names like IBM, Oracle, Computer Associates and the like are labelled as compatible with Red Hat Enterprise, and you can guarantee that this will be the case; it can't be denied that even though something claims to be compatible with the non-Enterprise version, your server is much more at the mercy of some undiscovered kernel bug that crept in via one of several dozen new releases. Oh, and still on the subject of support, bear in mind that the Enterprise versions are the only ones that you can phone Red Hat and get support for (though bear in mind that AS is the only one for which you can buy 24x7, 1-hour response for). Finally, (but significantly) you do have those hardware-specific benefits that allow you to run the commercial versions (depending on which one you have) on something other than an x86 platform, with more than two processors, and with shedloads of memory.

OUR VERDICT

If you don't need the formal support and you're not trying to run the thing on an IBM mainframe, go for the freeware version (now marketed under the Fedora banner). If you crave the reliability and formal support of a commercial product, go for Enterprise.