Installation guide

Chapter 23. Upgrading Your Current
System
This chapter explains the various methods available for upgrading your Red Hat Enterprise
Linux system.
1. Determining Whether to Upgrade or Re-
Install
While upgrading from Red Hat Enterprise Linux version 4 Update 4 is supported, you are more
likely to have a consistent experience by backing up your data and then installing this release of
Red Hat Enterprise Linux 5.0.0 over your previous Red Hat Enterprise Linux installation.
To upgrade from Red Hat Enterprise Linux 4 you should bring your system up to date using
RHN before performing the upgrade.
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
Whitepapers available online at http://www.redhat.com/solutions/info/whitepapers/.
If you currently use Red Hat Enterprise Linux 4 Update 4, you can perform a traditional, installa-
tion 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 com-
pleted.
• Third party or ISV applications may not work correctly following the upgrade.
Upgrading your system installs updated versions of the packages which are currently installed
on your system.
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 ac-
tions in /root/upgrade.log.
Caution
As software evolves, configuration file formats can change. It is very important to
216