Red Hat

Sigh....

Ok... here's the TRUTH. RHEL 5 is a release. During its evolution it went from RHEL 5 service pack 1 (aka 5.1) through RHEL 5 service pack 4 (aka 5.4... so far).

If you want support, the ONLY way is to be at the latest level of RHEL 5. If a customer is NOT at RHEL 5.4 (for example), then the customer is NOT running patch updates for security and fixes and therefore can NOT be supported by Red Hat.

RH(EL)AS/ES 3 is a release
RH(EL)AS/ES 4 (aka RHEL 4) is a release
RHEL 5 is a release

Starting with Update 5 of RH(EL)AS/ES 4, Red Hat switched the name to just RHEL and changed from using "Update" to making things a "dot" number (looks like a minor release). There were some less than ethical reasons behind the change... sorry Red Hat.

So... RHEL 4.5 (new name) is really RH(EL)AS/ES 4 Update 5 and so on...

When you run an online update, you will automatically be taken to the latest Update <cough> "dot" level of the release.

5.0 is NOT a release
5.1 is NOT a release
5.2 is NOT a release
5.3 is NOT a release
5.4 is NOT a release

RHEL 5 IS the release... and when up to date... it will take you to the latest "dot" level. Anything less is an unsupported Red Hat product... likely not under subscription maintenance.

What Red Hat did with their "Update" to "dot" number change was wicked... it served to get around a bad set of assumptions they made moving to their new release. It was designed to make the world see a "new release"... when there really wasn't one.

If you want the full story.. here ya go... changes in the kernel (in particular) and libc got rid of a (bad) feature that OLD code needed in order to run. Red Hat ISVs did NOT want (or better, didn't know or even care) to recompile their apps. When RHEL 5 was released, LOTS of things broke. ISVs were NOT ready for RHEL 5... and obviously, the end user/customer got a tad bit upset. It was at this time that Red Hat did what BIG companies do... they... well... you can call it what you want. What Red Hat did in response was to create a HUGE marketing campaign for the release of RHEL 4.5... yes.... that meant that Red Hat "heard" the customer's pain and "created a special release" called 4.5 to prove that they were worthy of your continued support. All of this RATHER than going through the mess of telling the end user/customer something I call "the truth". Thus the end of using the word "Update" and the beginning of using "dot" numbers. And obviously... the confusion this has caused continues to this day.

I am curious about something cjcox. Are the dot versions merely patches and bug fixes or can they include new versions of software? I read this article that says that RHEL 5.6 will include php 5.3 as opposed to php 5.1 in RHEL 5.5. As you may well know php 5.3 is significantly different than php 5.2 or php 5.1.

The minor revisions are not just for patches but also sometimes include major updates to subsystems and software packages. Red Hat releases patches all the time which are available if you have a RHN subscription.

Packages such as PHP are independant of the distribution. It's just a package that can be upgraded at any time regardless of the release.

If PHP 5.3 is not included in RHN repositories, you can always install it by hand.

Some software however have special requirements. For example an old version of Oracle may claim it runs only on RHEL 5, and even if you manage to install it and make it work on say RHEL 4, you won't be getting any official support.