9. What does it mean to be stable

Being stable might just mean to run without crashes, but it can also refer to a lifetime model involving a STABLE branch, and one or more testing, unstable, -current evolving branches.

Usually, small distros can't be trusted for having enterprise-grade stability, mainly because of the scarcity of the resources, as manpower. There is also another rule of the thumb that usually works: the "original" distro is less buggy than the derivatives.

This works better with Slackware, which is practically bug-free (not counting the -current branch). The derived distros (SLAX, Wolvix, Vector, Zenwalk, etc.) provide some extra polish, customizations, extra packages, and... bugs.

Even Debian's "testing" branch is usually more stable than Ubuntu's releases.

What is rather strange is that some distributions have chosen to be "unstable by choice": Sidux, recently Arch... In a world where the increasing complexity of the software makes the bug management more and more difficult, choosing to be unstable just for the sake of being "on the bleeding edge" is not my cup of coffee.

This kind of instability doesn't mean the distribution should not behave as expected. The open source has brought the ability to always have the last version of an open-source software package, either by installing a binary package provided by the distro makers, or by building it yourself from sources. Having an entire distro always kept up-to-date is desired by many individual users, and it's also a distinct possibility: free of any charge for most. Does this mean it is a desirable approach from a corporate point of view?

It's rather the other way around. In a business environment where stability and system availability are of the utmost importance (some people really think of "business continuity", not of spinning cubes), the primary choices are something like Red Hat Enterprise Linux, Debian stable, SLED and SLES, Mandriva Corporate Server and Desktop. What do all of them have in common?

An assumed approach of stability, that is. For instance, when RHEL4 was released, only OpenOffice.org 1.1 was available. Throughout the supported lifetime of 7 years, RHEL4 will never get OpenOffice.org 2.x, regardless of the improvements it could bring. Only security patches and bug fixes will be applied. When deemed necessary, selected new features are backported to older releases, but the general rule is: make as much as possible to prevent the breakage of what is already working. This might be annoying to be unable to use the new ODT document format, but at least consistency is ensured within a multinational company that uses a given release of an enterprise distro. On occasions, some applications can get upgraded to the next major number: this happened with Firefox 1.0.x going Firefox 1.5.x with Update 3 of RHEL4.

Stability doesn't mean obsolescence. With RHEL (but also with other enterprise distros), relevant improvements are backported to the existing base system when it is essential for customers. During the lifetime of RHEL4, the included kernel 2.6.9 (a very stable one, BTW) will not get a version upgrade. When Dell included in its Precision 390 workstations the BCM5754-based Broadcom Ethernet Controller, which only started to be supported with lernel 2.6.17, Red Hat has backported the corresponding changes to the existing 26.9 kernel, thus making possible to be certified for the Dell products that use BCM5754. You don't have to worry when buying a new Dell computer: it will work with your software.

This business definition is despised by the regular Linux user, and this might explain why the Arch Linux aficionados were so vocal to defend their "rolling-release never to reach 1.0" development model.

From a corporate standpoint (and corporate adoption is essential for the survival of Linux!), using Linux does not mean doesn't only mean browsing the Internet, listening MP3s and watching DVDs, and writing CDs/DVDs.