Apart from differences as you go from one release to another, a proprietary operating system like Windows is the same no matter how you get it. Linux distributions (or 'distros') differ considerably, however. Although they're all based on the same -- or very similar -- core Linux software (kernel), they generally have different user interfaces and varying amounts of bundled application software. As a result, what you actually get, and what you can do with it, will vary widely.
The level of documentation, support and other services available will also vary, as will the amount you’ll have to pay to obtain, deploy and support Linux in your organisation. Some of the free distributions are very specialist and are aimed more at the hobbyist and home users, with minimal support and a fast release cycle. More stable distributions designed for business use are better supported and have slower release cycles, but are becoming increasingly expensive.
As with Windows, there are different desktop and server versions of most Linux distributions. Some vendors also offer so-called 'LiveCD' implementations that can be booted from CD-ROM rather than requiring hard disk installation -- a good way of evaluating the software.
For a complete list of the, literally, hundreds of Linux distributions available, check out www.distrowatch.com. The top five Linux business 'brands' are briefly outlined below.
Very much the market leader in the Linux business sector, Red Hat recently divested itself of its personal distribution to concentrate on the Red Hat Enterprise Linux (RHEL) line. Available for both servers and desktops, RHEL is a well documented and supported business platform that's available through a wide variety of channels.
The Red Hat Linux consumer product was spun off as The Fedora Project in 2003. It’s still sponsored by Red Hat and can be downloaded and used for free. However, this version is now developed independently with community participation, has a much shorter release cycle than RHEL and is used primarily to test new technologies before they’re added to the enterprise product.
Red Hat Enterprise Linux can be specified for factory installation on server and desktop systems from leading vendors including IBM, HP and Dell.
Acquired by Novell in 2003, SUSE Linux software is available in several formats. There’s a freely downloadable consumer implementation simply called SUSE Linux available from www.opensuse.org, or a fully supported commercial package, currently SUSE Linux 10. However, for business use Novell recommends SUSE Linux Enterprise Server (SLES), based on an earlier implementation, which is better supported with a much slower release cycle. At the time of writing, for example, SLES 10 is only just being readied for launch several months after the introduction of the consumer version.
Novell also offers a business desktop distribution, Novell Linux Desktop; like SLES, this is based on earlier, stable, SUSE code. The company has also added Linux support to its NetWare platform to create the Novell Open Enterprise Server.
Novell /SUSE Linux software can be specified for factory installation by many of the leading industry standard server and desktop PC vendors. This again includes HP, Dell and IBM (which invested in Novell to help finance the SUSE purchase).
Originally known as Mandrakelinux, the Mandriva distribution was originally based on the Red Hat software, but with a KDE rather than a GNOME desktop interface. The latest server and desktop implementations can be downloaded from the Mandriva Web site or media packs ordered with varying levels of support and other services available by subscription.
The usual bundle of application software is included with the Mandriva product. Companies looking for a fully supported stable release and an extended update cycle can look to the Mandriva Corporate Server and Corporate Desktop packages, which are based on earlier releases.
Most hardware vendors certify their systems for use with Mandriva Linux and in Europe some HP notebooks can be ordered with the desktop distribution preinstalled.
One of the oldest Linux distros, Debian is a totally free implementation that, although not as popular as Red Hat or SUSE, is widely used in the business market. It has a slow release cycle and is therefore more stable than most of the consumer-orientated free distros. Debian has now largely been superseded by a distribution based on it, Ubuntu.
Based on the Debian distribution, Ubuntu is currently the most popular free implementation of Linux. It attracts wide community support and it’s possible to buy into a range of commercial support services, both from developer Canonical and from third-party organisations. Server and desktop implementations are both available, with a good selection of bundled applications. New versions are released every six months and there’s good support from the hardware vendors.