For quite some time now, IT budgets have been increasingly tight. Managers and systems programmers are being told repeatedly to reduce costs. IBM has generated considerable interest in the Linux (and particularly mainframe Linux) operating system as a way to do this. Unfortunately, the press has touted Linux as “free,” as in no cost, but it’s more proper to view it as free—in that it allows users many freedoms. This confusion has resulted in many people being told to investigate mainframe Linux with absolutely no money to spend on the project. That’s feasible for proof-of-concept-type projects, but production systems that require system tools, maintenance, and support are another matter. If the proof of concept shows acceptable ROI, a business case can be made to spend money to save money.

This article surveys commercial and no-cost Linux distributions available for the mainframe, identifies the terms for evaluation and support options, and offers some insight into the characteristics of the various distributions.

Linux/390 Distributions Available in North America

The very first was what is now called Marist File System: The installation consisted of unloading a “tarball” and configuring the network. Soon after the release of this system, Millenux in Germany made ThinkBlue available for S/390, and then followed up with a 64-bit version for zSeries. While both of these distributions were and still remain available for no cost, they’re also obsolete and shouldn’t be used, since there are more current distributions available.

When IBM decided to actively market Linux, it signed agreements with three Linux distribution providers: SUSE, Red Hat, and Turbolinux. The agreements required the partners to provide Linux distributions for all of IBM’s hardware lines, including S/390 and zSeries. Since then, Turbolinux has been acquired by a Japanese company and no longer serves the North American market, nor do they produce a mainframe Linux distribution. In terms of commercial Linux distributions for the mainframe actively being sold in North America, that leaves only SUSE and Red Hat.

SUSE was the first company to market a commercial Linux distribution for the mainframe. As a result, it garnered nearly the entire early market share and still maintains quite a lead over its competitor, Red Hat. Due somewhat to fortunate timing of Linux kernel releases, they’ve been producing newer versions sooner than Red Hat by several months.

SUSE has also been receiving important certifications for its SUSE Linux Enterprise Server (SLES) platform from companies such as SAP, Oracle, and IBM. Beginning with SLES7, SUSE began to position SLES for the enterprise market. It produces less frequent major revisions, providing maintenance and support for years beyond initial general availability, etc. SUSE also continued developing and supporting its non-enterprise versions, SUSE Personal and SUSE Professional. Novell acquired SUSE in January 2004, giving SUSE Linux access to Novell’s more extensive sales channels and more credibility in the North American enterprise computing market.

In the U.S., Linux is nearly synonymous with Red Hat. As a result, when Red Hat made its mainframe distribution available, many people wanted to give it a try if only because they were already running Red Hat on Intel hardware and wanted to standardize on one distribution. Not long afterward, Red Hat changed its business model to focus entirely on the enterprise market, dropping development and support for its “consumer” versions. This alienated some of the company’s long-standing consumer version user base while attracting others who run businesses and want to work with suppliers that understand what a business needs. Although still struggling somewhat to achieve that understanding, they do appear to be working toward it. The transition has been difficult for both Red Hat and its users, but appears to be producing the better profitability that Red Hat needed and desired.

Fortunately, for everyone with no money to spend, there are several good, no-cost Linux distributions for S/390 and zSeries. Listed roughly in the order they became available:

- Debian, one of the oldest, non-commercial Linux distributions with a very large and dedicated developer community, is available for 31-bit systems and a 64-bit version is under development.

- Tao Linux, a Red Hat “workalike” distribution that’s produced by recompiling the Red Hat Enterprise Linux source packages after removing any trademarked items, is available in both 31-bit and 64-bit versions.

- Fedora, the Red Hat-initiated replacement for its consumer Linux platform is available in both 31-bit and 64-bit versions.

- Slack/390, a port of Slackware (the oldest existing commercial Linux distribution), is available for 31-bit systems and a 64-bit version is under development.

Note that all 31-bit versions of Linux will run under z/VM on 64-bit hardware in 31-bit mode with no problems. To the Linux system, it just looks as though it’s running on 31-bit hardware. While this doesn’t let you exploit the hardware to its fullest potential, it does mean you can test pretty much everything except the 64-bit capabilities.

Obtaining Evaluation Software

Both Novell/SUSE and Red Hat offer their products for trial and evaluation. Both companies provide complete copies of their distributions. What you get for your proof-of-concept project is exactly what you’d get by purchasing it.

Red Hat offers its evaluation software at no charge, but the time limit is fixed at 30 days. Many people find this an impossibly short amount of time to get anything significant done, since most mainframe Linux proof-of-concept trials involve nearly every support group a company has: network, mainframe security, midrange security, storage, disaster recovery, change control, operating system support, midrange system administration, etc. Most people who have tried to not involve these other groups in the interest of saving time found themselves failing miserably. Various reports indicate that when asked to extend the evaluation period, Red Hat hasn’t been willing to do so. Depending on your company’s relationship with Red Hat, they might be willing to bend a little. It’s worth asking the question.

Novell/SUSE: At the time this article was written, the exact status of Novell/SUSE’s evaluation software offerings was a little uncertain. Prior to Nov. 16, 2004, Novell/SUSE made the Intel version of its SLES software available for a 30-day trial via a no-cost download. You could purchase an evaluation software media kit for any of its supported architectures, but the price ranged from $150 for Intel, to $600 for S/390 and zSeries. This price included installation support and six months of maintenance. At the end of the six months, you were supposed to either buy or uninstall the software. At this time, it’s not known if they’ll continue to offer this as an option.

Beginning Nov. 16, 2004, Novell/SUSE began offering SLES evaluation software for all its supported architectures via no-cost download at www.novell.com/products/linuxenter-priseserver/eval.html. You’ll need to create a Novell user account and password to access the software, but there’s no charge for access. The Website calls this a “free 30-day evaluation of SUSE Linux Enterprise Server 9 complete with free installation support and upgrade protection for 30 days.” Since the phrase “upgrade protection” in connection with a free trial seems a little confusing, some explanation is in order.

For Novell’s non-Linux software products, they charge a licensing fee. This gives you the right to use their software. Optionally, you can purchase “upgrade protection” which entitles you to installation support, maintenance, and the right to upgrade to a newer version at no extra cost if a new version is released during the period the upgrade protection is in place. If you buy upgrade protection for any one of your licensed products, you must purchase it for all licensed copies of that product. For Novell’s Linux products, no license fee is charged. However, upgrade protection is a mandatory cost. In the context of trial software, this means you’ll have access to installation support and maintenance for a maximum of 30 days. At the end of the 30 days, you can:

- Uninstall the software

- Purchase the upgrade protection for all your installed systems

- Continue using the software, but without access to maintenance.

Note that most, if not all, third-party suppliers that certify their software on SLES require that Novell’s upgrade protection be in place. They want you to be able to keep your systems updated or they won’t consider your use of their software to be supported.

Novell/SUSE recently offered another no-cost evaluation option: Fill out the Web form at www.nov-ell.com/linux/ibm. You can fill out the Web form and have physical media mailed to you for both S/390 and zSeries. Along with that comes installation support and six months of maintenance. The Website doesn’t explicitly state that the offer can be changed or withdrawn at any time, but that’s the case, according to Novell. Again, you’ll need to create a Novell user account and password to access the form if you don’t already have one.

In the past, SUSE has been rather flexible about both the price and length of time for evaluations. While leading in the mainframe market, they’re a distant second with the Intel-based platforms. They seem to have been trying to use their mainframe market lead and flexibility to make inroads in the Intel market.

So, if you need more than 30 days to get everything set up and tested, Red Hat may not be workable. Depending on your needs, Novell/SUSE may not be an option, either, which brings us to the no-cost alternatives mentioned earlier. You can use any of them for as long as you want, in any way you want, with access to maintenance, to try to develop the best possible business case for your particular situation. Remember, it’s unlikely that third-party software suppliers will certify their products to run on these distributions. If that’s important to your intended use of Linux, then treat these as stepping-stones to a business case to purchase one of the certified commercial distributions.

Debian: At least one of the Debian for S/390 developers works for IBM as a Linux for S/390 and zSeries developer. This makes Debian unique among the mainframe Linux distributions. Several shops have installed Debian/390 and find that it works well. Debian has more than 8,000 packages available. Many have no use on a mainframe system, but large numbers do. Originally created using IBM’s Linux Community Development System (LCDS), the 31-bit platform has been available for several years; the 64-bit version is in development. One of the attractions of Debian is that you can install a truly small/minimal system, consuming little in terms of system resources. That’s because the Debian developers try to minimize inter-package dependencies as much as possible. This gives you the flexibility to install as few or as many packages as needed. Debian doesn’t use the Red Hat Package Manager (RPM) tool to install and manage software. Instead, it has its own package format (.deb) and package management tools. There are also tools to convert packages to and from other package formats, if necessary. Note that this doesn’t mean the packages will always work well when transferred to your system, just that it’s possible to do so.

Debian can be obtained from one of the Debian download servers located around the world. Debian has a unique tool named “jigdo” for “jigsaw downloader.” With a little setup and one command, jigdo lets you download pieces of Debian CD images from various servers, which are then reconstructed into complete CD images on your system’s hard drive. This is an interesting approach to the problem of very large and long downloads being interrupted and having to be restarted. Sine Nomine Associates, a research, consulting and IT services company, has used Debian for S/390 to produce a “drop-in” Secure Sockets Layer (SSL) server for z/VM, as well as SSH and SSL proxies. These are available for free download from the Sine Nomine Website and can greatly enhance your z/VM functionality.

Fedora: For shops interested in buying Red Hat Linux, Fedora might look attractive, since it’s developed by Red Hat with considerable community support. However, according to Alan Cox of Red Hat, Fedora for S/390 and zSeries is really not tested much, if at all. He also believes the Fedora installer probably won’t work on the mainframe. Also, Fedora isn’t an analog of the Red Hat Enterprise Linux product. Fedora is intended as a proving ground with a rapid development cycle for packages and features that may or may not wind up in the supported RHEL product line. There have been no reports in the Linux390 mailing list hosted by Marist College of anyone installing and using Fedora on the mainframe. If this doesn’t discourage you, Fedora for S/390 and zSeries can be downloaded from the Fedora download servers or one of its mirrors.

Tao Linuxis a much more reasonable stand-in for RHEL3, since it’s built from the official RHEL3 source packages. There have been reports of Tao Linux being installed and working on both S/390 and zSeries hardware. Original development of the mainframe Tao packages was done on real mainframe hardware. Since then, development and maintenance have been moved to a workstation running the Hercules mainframe emulator. Continued development and maintenance isn’t exactly a sure thing, but not unlikely, either. Tao Linux for the mainframe was created for the same reason as many other open source projects in that it “scratched an itch” of the person doing the port, Pasi Pirhonen. He needed a no-cost alternative to RHEL3, so he created one, and then made it available to others. While Pasi doesn’t officially provide support for the mainframe version, he has answered questions and provided help when the rest of the community was unable to resolve problems.

Slack/390 is the result of two Slackware users connecting via the Linux390 mailing list and deciding to port their favorite Intel Linux distribution to the mainframe. Mike Kershaw of Marist College and I both liked the simplicity and lightweight attributes of Slackware, and thought it would be a great project to port it to the mainframe. We also saw a need for a no-cost Linux distribution for the mainframe, similar to how the Marist File System had been, but not based on Red Hat, since we didn’t care for RPM much. When we started, Debian for the mainframe wasn’t available, and Slackware had always been available for free download or purchase, so it seemed a good fit. Originally, development was done on Marist College’s z/VM system. Since then, various versions have been created on the LCDS, and now the Open Source Development Lab’s z990, which Marist College supports. This is where the 64-bit development is happening now. Slack/390 tries to track Slackware development as closely as possible, while making the necessary allowances for the differences in the mainframe architecture. Slackware and Slack/390 don’t use RPM for package management. Slackware and Slack/390 packages (.tgz) use the commands from the “pkgtool” package to do that. This is written entirely in bash scripts, making it completely portable across hardware architectures. Patrick Volkerding, creator and developer of Slackware, recently declared Slack/390 to be an official port of Slackware.

What, No Free Version of SUSE Linux?

There’s no analog or SUSE Linux Enterprise Server available. For quite some time, SUSE didn’t make the source packages of their enterprise software available except to paying customers. This was most likely in reaction to what happened when they released SUSE 7.0 for the mainframe and made it freely available. Many people downloaded the software and almost no one bought it. When SLES7 was being developed, the beta code was available for free download, but not the general availability code. Since then, there have been no freely downloadable versions of SLES for the mainframe. After Novell acquired SUSE, they initially made SLES for Intel available for evaluation via a no-cost download, and now, all architectures. This includes the source packages, so someone may invest the time necessary to rebuild the platform for the mainframe. That doesn’t appear to have happened yet.

Getting Maintenance & Support

A distinction should be drawn between maintenance and support. Maintenance is just that: patches or package upgrades to fix problems that other people have reported. Think of it as the equivalent of monthly PUTs for your more familiar operating systems. Support is a mixture of advice, consulting, hand-holding, etc., but mainly it’s fixing problems that you report and need resolved immediately. This would be the equivalent of calling the IBM Support Center to obtain a workaround for a problem. Every shop needs maintenance. In the Linux world, not everyone needs support—at least not all the time.

Maintenance

All Linux distributions provide maintenance. SUSE has YaST Online Update (YOU). Red Hat has Red Hat Network and the up2date command. Fedora and Tao Linux use up2date and “yum” repositories, or you can just download new packages from the download servers. Slack/390 provides updates via the “/patches” subdirectory on the download server. Debian uses “apt” to download updates and any prerequisites.

For SUSE and Red Hat, maintenance is bundled in the license price. In a real sense, what you’re paying for is access to the maintenance in precompiled (i.e., “binary” form) and the tools to minimize the effort of installing it, not the distribution itself.

The non-commercial distributions provide maintenance, also at no cost to you, but you may not get all the features that YOU and RHN provide. Of course, you may never use all the functionality provided by YOU or RHN, either. Many shops get by just using the basic features they need.

Support

Support for the commercial distributions is always available directly from the distribution providers. You do have other choices, though, and you need to be aware of the consequences of making them.

When you buy SLES from Novell/SUSE, the cost of support is separate from the cost of the upgrade protection. You’re not required to buy support, either from Novell/SUSE or anyone else. This is also true if you buy SLES through someone other than Novell/SUSE. Novell sees this as a way to give its customers choice and flexibility. Some of Novell’s business partners sell SLES as well as support for it. IBM Global Services (IGS) does the same, via their SupportLine for Linux offering. IGS’ official policy is that it will only sell a mainframe Linux distribution when it’s in conjunction with a SupportLine for Linux contract.

When you buy RHEL from Red Hat, support is included in the price. You have the choice of selecting standard or premium support. Some shops have bought RHEL with standard support directly from Red Hat, and then bought SupportLine for Linux from IBM. Because they were medium to large IBM “Gold Card” customers, this wasn’t a large expense for them. Your situation may be different, of course. #When you buy RHEL from someone other than Red Hat, make sure you understand who you can and can’t call for your support. In the Intel market, several companies that sell RHEL have agreements with Red Hat that don’t let you call Red Hat directly. This may or may not be the case with Red Hat for S/390 and zSeries, but make sure you know what your obligations are.

Spend at least a little time thinking about the trade-offs of buying support from someone other than the distribution provider. Some shops like the convenience of having one company to call for any and all mainframe operating system problems. The counter argument is that SUSE and Red Hat know their distributions better than anyone else.

Getting support for the non-commercial distributions is simultaneously:

- Easier because you’re not tied to a small number of choices

- Harder because you or your management may not trust a small company to do the job.

Many executives and managers want to work with support companies that have offices and employees all over the world. Companies that fit those requirements aren’t likely to be interested in supporting a non-commercial distribution with which they have little or no experience. Companies that are known to provide support for mainframe Linux are:

- Mainline Services Group

- Sine Nomine Associates

- UTS Global.

In particular, Sine Nomine Associates is known to provide support for the no-cost Linux/390 distributions such as Debian and Slack/390.

There’s no-cost support available from the Linux-390 mailing list. Marist College hosts this mailing list and it’s been an enormous resource for many people just getting into mainframe Linux. The list’s subscribers have a wide range of skills. Some are largely Linux-oriented, while others have mostly a mainframe background. Subscribers include many z/VM systems programmers, z/OS systems programmers, and even some SUSE and Red Hat employees. The IBM Linux developers from Boeblingen, Germany, have been frequent contributors, as have IBM employees from many other areas. The list is friendly to newcomers, and has a low noise-to-signal ratio. If you do nothing else when first starting to work with Linux on the mainframe, subscribe to this mailing list.

There’s also a Website that was started with the intent of being a companion to the mailing list, linuxvm.org. It has a huge collection of Linux and Linux/390-related links, mainframe Linux-specific “HOWTO” documents, and many presentations from technical conferences such as SHARE, WAVV, and IBM’s zSeries Expo.

Conclusion

It’s entirely possible to install and test Linux on your mainframe with little or no initial cash outlay. Depending on your company’s level of self-sufficiency, it’s also possible to go into production without spending a lot of money. For many companies, this won’t be an option, and a solid business case will need to be developed to justify the expense of acquiring operating system software, system management tools, and support contracts. Using no-cost Linux distributions for the mainframe can be helpful in developing that business case.

TO LEARN MORE, VISIT THESE WEBSITES:

- Debian project: www.debian.org/

- Fedora: http://fedora.redhat.com/

- Hercules project: www.conmicro.cx/hercules/

- Linux-390 mailing list:www.marist.edu/htbin/wlvindex?linux-390

- Linux-390 mailing list companion Website:http://linuxvm.org/

- Linux Community Development System:www.ibm.com/servers/eserver/zseries/os/linux/lcds/

- Mainline Services Group: www.mainline.com/

- Novell download site: www.novell.com/products/linuxenterpriseserver/eval.html

- Novell licensing programs training:www.novell.com/licensing/training/

- Novell Web form: www.novell.com/linux/ibm/

- Novell/SUSE evaluation software:www.novell.com/linux/download_linux.html

- Slack/390: www.slack390.org/

- Slackware: www.slackware.com/

- Sine Nomine Associates: www.sinenomine.net/

- Tao Linux: www.taolinux.org/

- UTS Global: www.utsglobal.com/