This appendix explains the various methods available for upgrading
your Red Hat Enterprise Linux system.
Although upgrades are supported from Red Hat Enterprise Linux versions 2.1 and
3 by the Red Hat Enterprise Linux family on x86 processors (or Red Hat Enterprise Linux 3 on an AMD64, EM64T
or Itanimum system), you are more likely to have a consistent experience
by backing up your data and then installing this release of Red Hat Enterprise Linux
4 over your previous Red Hat Enterprise Linux installation.
This recommended reinstallation method helps to ensure the
best system stability possible.
For more information about re-installing your Red Hat Enterprise Linux system,
refer to the Technical Whitepapers available online at https://www.redhat.com/docs/wp/.
If you currently use Red Hat Enterprise Linux version 2.1 or 3 on an x86 system
(or Red Hat Enterprise Linux 3 on an AMD64, EM64T or Itanimum system), you can perform a
traditional, installation program-based upgrade.
However, before you chose to upgrade your system, there are a few
things you should keep in mind:
Individual package configuration files may or may not work after
performing an upgrade due to changes in various configuration file
formats or layouts.
If you have one of Red Hat's layered products (such as the Cluster
Suite) installed, it may need to be manually upgraded after the
Red Hat Enterprise Linux upgrade has been completed.
Third party or ISV applications may not work correctly
following the upgrade.
Upgrading your system installs the modular 2.6.x kernel as well as
updated versions of the packages which are currently installed on your
The upgrade process preserves existing configuration files by renaming
them with an .rpmsave extension (for example,
sendmail.cf.rpmsave). The upgrade process also
creates a log of its actions in
As software evolves, configuration file
formats can change. It is very important to carefully compare your
original configuration files to the new files before integrating your
It is always a good idea to back up any data
that you have on your systems. For example, if you are upgrading or
creating a dual-boot system, you should back up any data you wish to
keep on your hard drive(s). Mistakes do happen and can result in the
loss of all of your data.
Some upgraded packages may require the installation of other packages
for proper operation. If you choose to customize your packages to
upgrade, you may be required to resolve dependency problems. Otherwise,
the upgrade procedure takes care of these dependencies, but it may need
to install additional packages which are not on your system.
Depending on how you have partitioned your system, the upgrade
program may prompt you to add an additional swap file. If the upgrade
program does not detect a swap file that equals twice your RAM, it asks
you if you would like to add a new swap file. If your system does not have
a lot of RAM (less than 128 MB), it is recommended that you add this swap