Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER ADMINISTRATION, Руководство по установке

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Chapter 24.
257
Upgrading Your Current System
This chapter explains the various methods available for upgrading your Red Hat Enterprise Linux
system.
24.1. Determining Whether to Upgrade or Re-Install
Red Hat does not support upgrades from earlier major versions
Although
anaconda
provides an option for upgrading from earlier major versions of Red
Hat Enterprise Linux to Red Hat Enterprise Linux 5.5, Red Hat does not currently support
this. More generally, Red Hat does not support in-place upgrades between any major
versions of Red Hat Enterprise Linux. (A major version is denoted by a whole number
version change. For example, Red Hat Enteprise Linux 4 and Red Hat Enterprise Linux 5
are both major versions of Red Hat Enterprise Linux.)
In-place upgrades across major releases do not preserve all system settings, services or
custom configurations. Consequently, Red Hat strongly recommends fresh installations
when upgrading from one major version to another.
While upgrading from Red Hat Enterprise Linux version 4 Update 4 is technically possible, you are
more likely to have a consistent experience by backing up your data and then installing this release of
Red Hat Enterprise Linux 5.5 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/rhel/resource_center/
.
If you currently use Red Hat Enterprise Linux 4 Update 4, 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 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
actions in
/root/upgrade.log
.