Current is&t Issue

Volume 20

No. 6  July/August 2005

Software Spotlight: IS&T Supports Red Hat Enterprise Linux 4

Bill Cattey

Recently, Red Hat released Red Hat Enterprise Linux 4 (RHEL 4), the successor to RHEL 3. IS&T fully supports this new version, along with the Red Hat Network update service. RHEL 4 has many new features and supports more recent hardware than RHEL 3. Red Hat has posted a hardware compatibility list.

What’s New?
RHEL 4 offers several technology enhancements while maintaining a high level of compatibility with prior releases. New features include the following.

• The latest kernel, version 2.6, enhances security, performance, and functionality. These benefits, however, have made it more difficult to port OpenAFS.
• Support for Security Enhanced Linux (SELinux) has been incorporated. IS&T currently recommends leaving the SELinux features turned off until it has had time to fully test them. However, IS&T expects that, with time, SELinux will be used widely.
• Conformance with the Standardized Application Binary Interface (ABI) is now in place. This will require more applications to be recompiled initially, but once ABI is fully implemented and adopted, applications should run regardless of which Linux distribution you use.

For a complete list of new features, see the RHEL 4 Release Notes.

Application Updates
Both Red Hat and IS&T have made related updates to a variety of Linux applications.

From Red Hat

• Open Office has been updated to version 1.3.
• The Evolution email client and other GNOME-based applications have added functionality and comply with version 2.8 of the GNOME toolkit.
• The web browser has changed from Mozilla to Firefox, for improved performance and functionality. IS&T has made Firefox the default in the new Athena release as well.

From IS&T

• Acrobat Reader has been updated to version 7.
• IS&T now supports and offers for download Linux Pine, the email program based on the Athena-supported Pine client.
• Updated binaries are available for the Zephyr instant messaging system and the Kerberized LPRng printing system.

More Liberal Licensing
Previously MIT was licensed only for the RHEL AS and WS products, with the restriction that personally owned systems could only run WS. MIT now has a broader site license that lets community members run all four RHEL products – AS, ES, WS, and Desktop – without restrictions on what can run on personal systems. As a practical matter, IS&T fully supports and recommends AS and WS, while offering only best-effort support for ES and Desktop.

Note: For a brief description of the products, see the overview [PDF file] from Red Hat.

Known Issues
You can ease the transition from RHEL 3 to RHEL 4 by being aware of a few known issues.

• Confusing Red Hat Network registration prompts. When you first install RHEL 4, you’re asked to register for the Red Hat Network update service. If you say ‘yes,’ you are sent to the for-pay Red Hat server rather than the MIT server that is free to community members. If you say ‘no,’ you get periodic pop-ups asking you to do so. The MIT Red Hat Network registration system silences the reminders. Say ‘no’ and register with the MIT server by following the instructions at http://web.mit.edu/ist/topics/linux/rhn.html.

• Delays porting OpenAFS. Porting and validating OpenAFS for the 2.6 kernel and RHEL 4 has taken longer than planned. IS&T expects to fully support OpenAFS in a matter of weeks. If you need AFS, stay with RHEL 3 for now.

• Long upgrade time and potential data loss. Upgrading from RHEL 3 to RHEL 4 takes roughly three hours for a 1GHz system – as opposed to about 20 minutes for a reinstall. The upgrade script will destroy local data if you try to switch OS products, for example from WS to AS, as part of the upgrade.

• Need to update MIT applications. When you migrate from RHEL 3 to RHEL 4, you will need to update your MIT applications because new binaries are required for RHEL 4. You may also need to refresh your Kerberos configuration because the Red Hat Kerberos update may overwrite the MIT configuration.

A detailed list of known issues and resolutions can be found at http://itinfo.mit.edu/article?id=7763.

How to Obtain RHEL 4
Existing RHEL 3 users can update to RHEL 4 using Red Hat Network, following the procedure documented at http://itinfo.mit.edu/article?id=7792. ISO images of the RHEL 4 CDs are available (MIT certificates required) at https://web.mit.edu/rhlinux/rhel-4.0/.

To obtain a copy of the Red Hat Enterprise Linux CD set (MIT certificates required), go to https://web.mit.edu/ist/products/vsls/mitlinux/.

Getting Help
The Red Hat Enterprise at MIT page is located at http://itinfo.mit.edu/product?vid=671. If you need assistance with RHEL 4, contact the Computing Help Desk at <computing-help@mit.edu> or 253-1101.

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