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Review: RHEL 4 delivers strong features, few thrills

The thrill is gone, but the basics are covered in Red Hat Enterprise Linux 4, says reviewer Kenneth Milberg.

The much anticipated release of Red Hat Enterprise Linux (RHEL) v.4 has arrived, painting Boston red at LinuxWorld Expo & Conference this week. With this conservative product, Red Hat steps up as a full-fledged Linux 2.6 provider. I just wish they'd stepped a little higher.

Novell has had an enterprise version running the 2.6 kernel for a year. Red Hat incorporated many of the elements of the 2.6 kernel into RHEL 3, but it still was not where it could have been had the company decided to break with tradition and issue a new release prior to their typical 12-18 month lead cycle. After reviewing RHEL 4, I'm left wondering if this release is so much better that businesses using RHEL 3 will rush to upgrade.

I evaluated the RHEL 4 Advanced Server (AS), the 32-bit, x86 version. (There is also a 64-bit version available as well.) I installed it on a generic PC with 256 mg RAM, a 1.2 GHz Celeron processor and 40 GB of disk. I used a 14 GB partition that I created with Partition Manager, version 8.0.

My test system is a floor-standing no-name PC that functions as a fileserver, but it also used for a few desktop functions. The wireless LAN card that I have installed in the Server (Linksys WMP11) is not PCMCIA, but is in fact a PCI Card that I installed in one of the available slots on the PC server. I also chose to re-partition a Windows Server, only because I also wanted to test out the latest release of Partition Magic for XP and determine how it co-existed with RHEL v.4. Doing so, I was able to provide some information for those folks who may be evaluating Linux, but are not yet ready to throw out their Microsoft products just yet.

Red Hat has four different versions of this new product: AS, Entry Server (ES), Workstation (WS) and Desktop. (RHEL 3 did not start out with the desktop version, which was first released during May 2004.) The versions are marketed for the following customers: WS for client workstations that support technical engineering, developer and computer-aided design users; ES for small and mid-sized users; AS for high-end mission critical enterprise servers; and the desktop version for corporate users. Be advised that the desktop version does not support Itanium systems.


Let's start with some interesting tidbits of the new release, besides the 2.6 kernel (version 2.6.9-5.EL). There are options to run SELinux as a subsystem, enhanced auditing abilities, desktop productivity improvements, AutoFSv.4 , support for NFSv.4, better hardware support, SMP and NUMA enhancements, as well as newer versions of Samba (3.0), GCC (3.4), GNOME (2.8), MySQL (4.0) and some other applications.

There are structural and technical improvements in this release, some of which include filesystem structures (ext3 is now default); a newer version of Logical Volume Manager, which should allow for easier administration of disk; and virtual memory, I/O subsystems and process scheduler improvements that now provide support for hyperthreading CPUs.

Looking at the server functionality and operability of RHEL V.4, I must say that I am impressed with many of the enhancements that are a part of this release. Though many have criticized Red Hat by saying most of the enhancements are only because they are riding on the coattails of the 2.6 kernel, I'll say there are enough features that Red Hat brought to the table that make the product well worth running as a file or applications server.

I migrated the operating system with ext3 as the default file system and have also tested and configured the LVM2 functionality that comes with Red Hat. I came away from these tests very impressed. RHEL AS is a total server solution for any large environment that should be able to run the most demanding database and ERP applications.

Improved file system capabilities should definitely make a difference in how Linux is perceived in the enterprise. These improvements include ext3 performance and dynamic file system expansion supporting file sizes as large as 8TB; LVM2 support. I liked such new features as read/write snapshots and a wonderful new management GUI. Auto-mounting, through the inclusion of AutoFSv4, provides new methods of device access control.

The security capabilities of SELinux and how they are integrated into RHEL v.4, should also impact how Linux is perceived as a secure infrastructure solution. Mandatory access controls are just one of many features that that SELinux has to offer, by the predefined policies that can be configured to ensure that only those that you want to access the system, will be accessing it.

That said, there are some features I would have liked to see in this release that are missing, and I'll discuss them later in this review.


The installation package includes five CDs, compared to six in RHEL 3. The last CD is only required for additional application installations. One important piece of advice: Be very careful about choosing the option about testing the CDs before you install. When installing the operating system, there is an option that allows one to test the CDs prior to the installation. Conservative person that I am, I chose that option. Unfortunately, doing so slowed down the installation process for me for several hours. That is because disk one kept on coming up bad, even though I spent a good hour cleaning the CD.

Finally, I decided to try the install regardless of the errors, and it worked perfectly! I'm not sure if this is a bug in the software, or if the CD was in fact a bit flaky, but it certainly lengthened the time that it took me to install the software and caused me some nervous moments, as I really needed this version to work.

Once this hiccup ended, the install itself went fairly smoothly, as I created a separate partition for this installation on one of my test PCs. The partitioning process (using Partition Magic 8) took longer than the entire installation, which I completed in less than one hour. One mistake I did make was choosing the option to partition with Linux on Partition Magic, which creates the ext2 filesystem only. This caused the Red Hat install to create the filesystems using ext2, rather than the improved ext3 filesystem, which is supposed to be the default. If you use Partition Magic, don't make this mistake!

During the Red Hat installation, there are several options to working with the partitions. I tried the auto-install, but it did not work. I think this might have been because of the way I partitioned the Linux partition with Partition Magic. So, I configured the partition with Disk Druid, a nifty partitioning tool that ships with the product.

Disk Druid can handle most partitioning requirements for installations, but it does not do complex tasks, which is why I needed Partition Magic. It would be nice if there was a subsequent version of RHEL that allowed someone to really work with existing Windows partitions without having to do the work with Windows software (i.e., Partition Magic), but I'm not holding my breath. While Druid will search for empty space to install partitions, it will not shrink existing partitions, which is a process that one must often do when installing Linux on what was a single partition Windows PC.

Continue to part two: RHSM, Networking, GNOME & OpenOffice

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