RHEL 5.4 released

That is not true. Companies want to be able to install and run the same baseline operating system that behaves the same way and was tested from the start as long as possible.

When we did acceptance tests for RHEL 5.2 (few companies start with RHEL 5.0) we want to be sure that when we install or upgrade RHEL 5.3 and RHEL 5.4 that the system behaves exactly the same way. The risk of a kernel behaving different under a certain situation (load, hardware defect, etc...) is reduced a lot by staying with 2.6.18 rather than move gradually to 2.6.35 (?) over its 7 year support period.

For certain applications (think: firefox or lftp) re-basing them to a newer version is possible and sometimes needed, but doing the same with the kernel is simply too dangerous.

If you take 3rd party software into account (think: Oracle, SAP, CA software), it becomes even a more problematic as it often takes one year to 18 months before the first applications are being supported on a new RHEL releases. Imagine what would happen if Red Hat would change the kernel underneath every 2 years ? Vendors would want to re-certify their applications.

One problem that is becoming apparent in big companies is that Red Hat's move to a 3 year release cycle is making 7 years of support insufficient. With a 4 year hardware life cycle it is becoming hard to install systems that have been tested properly and are supported for the next 4 years.

I recently blogged about this here:

http://dag.wieers.com/blog/is-7-years-of-rhel-support-sti...