Tips & Tricks
Featured Article: Migrating from Red Hat Linux to Red Hat Enterprise Linux v.3 or Fedora Core v.1.


A few years ago there was just one Red Hat Linux. As acceptance grew and Linux reached further into enterprise computing, one Red Hat Linux product could no longer be all things to all users. That's why in 2002 Red Hat created what's now known as Red Hat Enterprise Linux. Stable, supported, certified—Red Hat Enterprise Linux has become the Linux standard.

The Fedora Project was introduced in late 2003. Built for and with the help of the open source community, the Fedora Project is for developers and high-tech enthusiasts using Linux in non-critical computing environments.

You've gone to:

http://www.redhat.com/software/rhelorfedora/

And you've chosen the product or project that fits you best.

Now. How do you get from where you are, to Red Hat Enterprise Linux v.3 or Fedora?

Migrating From Red Hat Linux to Red Hat Enterprise Linux v.3

Red Hat Linux and Red Hat Enterprise Linux are intended for different markets and are two very different operating systems. Red Hat Enterprise Linux is a completely different code base than the Red Hat Linux retail products. Customers moving from Red Hat Linux to Red Hat Enterprise Linux will find that the installer does not offer an option to upgrade. This is because automated upgrades have historically been unsuccessful due to the vastly added community, proprietary, custom, or otherwise non-Red Hat code on top of the standard Red Hat Linux distribution. That being said, migrating from Red Hat Linux retail products to Red Hat Enterprise Linux products should be a fairly simple undertaking as the releases have similar tools and capabilities. System administrators should be clear that the recommended way to migrate between Red Hat Linux and Red Hat Enterprise Linux is to backup data on the existing system and run a clean installation of Red Hat Enterprise Linux. Red Hat technical support can provide assistance to customers who need to configure services and restore data on the new Red Hat Enterprise Linux installation.

Users migrating applications from Red Hat Linux to Red Hat Enterprise Linux v.3 should consider the possibility of complications arising from changes in runtime libraries, compilers, and other fundamental OS components. Where possible, it is wise to deploy Red Hat Ready or Red Hat Certified Applications that have been tested and are officially supported.

Compatibility with Red Hat Enterprise Linux v.3 should not be a problem provided the application adheres to the POSIX and Linux Standards Base criteria. Applications that were not developed with these standards will make the migration challenging. Please refer to the following table for a complete list of Red Hat Enterprise Linux v.2.1 supported applications.

http://www.redhat.com/solutions/migration/applist_chart.html

For more information the Linux Standards Base certification, please refer to the following article:

http://www.redhat.com/partners/press_partner_fsg.html

Developers should be aware that C++ version 3 runtime libraries are not API compatible with the previous C++ version 2 runtime libraries. Administrators with questions about backward source compatibility should refer to the GCC documentation at: http://gnu.gcc.org

Application Binary Interface compatibility should also be evaluated when migrating from Red Hat Linux or Red Hat Enterprise Linux v.2.1 to Red Hat Enterprise Linux v.3 because the GCC compiler that ships with Red Hat Enterprise Linux v.3 uses a new C++ ABI standard.

Migrating from Red Hat Enterprise Linux v.2.1 to Red Hat Enterprise Linux v.3

Customers migrating from Red Hat Enterprise Linux v.2.1 to Red Hat Enterprise Linux v.3 should find the upgrade path straightforward and familiar. As previously mentioned, Red Hat suggests the best approach when migrating to a new operating system is backing up data and performing a clean installation, particularly when third-party applications or non Red Hat RPMs are involved. This is the recommended way to move from Red Hat Enterprise Linux v.2.1 to Red Hat Enterprise Linux v.3.

Any migration should be carefully planned and scheduled during a time that is not disruptive to users. It is important to verify hardware compatibility prior to initiating the migration. Red Hat hosts a Hardware Compatibility list where device supportability can be verified at:

http://hardware.redhat.com/hcl/

Data should be backed up using any of numerous open source or proprietary backup applications. Most production networks have automatic back-up systems in place. Many proprietary applications are certified on Red Hat Enterprise Linux products such as VERITAS NetBackup for this purpose. In the event that that an automated backup system is not in place, Red Hat Enterprise Linux products include utilities such as tar, mt, dump, and Amanda to assist with data backup and recovery. Red Hat additionally recommends making a complete backup of your existing data as it is better to have what you do not need than to need what you do not have. At a minimum, make certain to backup configuration files for active services, databases and spools for active services, custom scripts, and networking subdirectories.

The sizes and locations of partitions created for Red Hat Enterprise Linux v.2.1 do not need to change much when moving to Red Hat Enterprise Linux v.3. When performing the Red Hat Enterprise Linux v.3 installation, administrators should format critical partitions such as the root and boot. Partitions that contain user home directories or other operating system exclusive information do not necessarily need to be formatted. Administrators can elect not to format those partitions during the Red Hat Enterprise Linux v.3 installation. Please refer to Chapter 4 in the Red Hat Enterprise Linux Installation Guide for your architecture available online at:

http://www.redhat.com/docs/manuals/enterprise/

Upgrading from Red Hat Enterprise Linux v.2.1 to Red Hat Enterprise Linux v.3 It is technically feasible, although not recommended as the most stable method, to upgrade to newer versions of the same Red Hat Enterprise Linux product (for example Red Hat Enterprise Linux WS v.2.1 to Red Hat Enterprise Linux WS v.3). Administrators can specify a boot parameter to upgrade non-production or test Red Hat Enterprise Linux systems. When performing an upgrade, customers see the familiar installation page just before the installer initializes. At the "boot:" prompt at the bottom of the screen, specify:

linux upgrade
This begins the upgrade process for Red Hat Enterprise Linux. Again, this is not the recommended way to upgrade, however, it is effective for minimal systems that are not running third-party applications or do not have a critical role in a production environment. If the above command does not result in the installer beginning to upgrade the system, type:
linux upgradeany
This minimizes installer checks. Please refer to Chapter 4 of the Red Hat Enterprise Linux Installation Guide for your architecture available at:

http://www.redhat.com/docs/manuals/enterprise/

Migrating from Red Hat Linux 8.0 or 9 to Fedora Core:

If you are a tester, developer, or just enthusiastic about the newest bits in the Linux community, you may want to switch from RHL to Fedora.

This works much as it has in the past. Start by getting a copy of Fedora Core v.1 from the Fedora Project home page:

http://fedora.redhat.com

You can then migrate (eg saving rsync'ing your home directory and data somewhere safe, and rsync'ing back in post install). For the more daring, you can simply boot into the installer and choose upgrade.

If you run into some snags, join one of the Fedora Project mailing lists and hack away.