Can I walk into a datacenter, find the mainframe's CD-ROM drive, and install Linux off my Red Hat CDs? Can I go to eBay, pick up a big honkin' S/390 for a few hundred bucks, load StarOffice, and have the fastest word processor in the world? Would that make me some sort of freak?
Part of the confusion stems from the alphabet soup of IBM's system lineup. If you want to buy a new system from IBM, your choices fall into one of four groups: The zSeries, which typically runs z/OS, are the mainframe systems. They're powered by 31-bit hardware. (Yes, that's 31.) Next down the line is the iSeries; these are the old AS/400s, with IBM's PowerPC chips inside. The same chips also are inside IBM's pSeries, which runs AIX, Big Blue's flavor of Unix. Finally, there's the xSeries -- all the Intel-based stuff.
In some way, shape or form, Linux runs on all of them. Those shapes and forms depend on IBM's open source code, and what Linux distributors like Red Hat and SuSE do with the code. There are two primary ways Linux runs on IBM's big iron. One way is natively. In other words, no other operating system or special software is required. It's the equivalent of wiping all traces of Windows off your computer, and replacing it with Linux or some other operating system. Linux can run natively on IBM's zSeries (the mainframes) and xSeries (Intel-based systems).
The other way is in a partition. For example, the native OS can be used to carve out a chunk of resources (like storage) and dedicate these resources to a separate instance of the native OS or another OS that IBM supports (like Linux). As a side note, the Datacenter Edition of Windows 2000 Server does this sort of partitioning, but it only allows you to run Windows in each partition. In most partitioned environments, the partitions don't interfere with each other. In essence, each partition is emulating a stand-alone computer running whatever OS was loaded into it. IBM has supported partitioning of its big iron into these sorts of virtual computers (IBM calls them "logical partitions" or "virtual machines") for what seems like forever. Whereas Linux can run natively on IBM's zSeries and xSeries, it can only run in partitions on the iSeries and pSeries.
One cool twist on the zSeries mainframes is that they can be partitioned physically as well as logically. This means that the mainframe can be carved into separate physical systems, each of which can run an OS (like Linux) in the native mode.
Why would IBM support this? It's pretty simple. Because Linux is a Unix variant, many enterprise applications can be ported to the open source OS. Once they're on the Linux code base, porting them to IBM's big-iron-specific Linux distributions is trivial. An example, according to SuSE vice president for Technology Partners Juergen Geck, is Software AG's database ADABAS/D. "Once Software AG ported the database to Linux," Geck says, "It took about a half a day to get it running on an IBM mainframe."
That sort of commonality within the IBM family kills two birds with one stone. First, it gives IBM customers a smoother migration path, regardless of which direction they are sizing (up, down, or lateral). Second, it creates some awfully compelling alternatives to Windows and competing Unix solutions -- particularly Sun's solutions. For example, for businesses concerned about the scalability or reliability of Windows, IBM provides an option for trying Linux on an Intel platform such as the recently introduced and very scalable x440 servers. To this IBM adds the ability to move up the food chain to something with a reputation for being bulletproof -- like a pSeries, iSeries, or zSeries system. With the partitioning that's available on the bigger iron, IT shops can consolidate 10 Linux computers into one system so that all of them can leverage the availability and scalability features of the host.
So where does SuSE fit into the picture? The open source nature of Linux gives IBM a chance to bend an OS that it doesn't own around its other intellectual property. This option is not readily available with Windows or Java. Windows is under the tight grip of Microsoft. Java is theoretically "bendable" through participation in the Java Community Process, but that still doesn't compare to how easy it is to get Linux running on IBM mainframes the way Big Blue wants. Who's going to argue -- especially when IBM open sources all the code to make it work? While IBM open sourced the code to run Linux on its various systems, it doesn't actually sell its own distribution of Linux. IBM has left it up to other distributors to pick up that open source, incorporate it into their distributions, and compete by offering something special beyond the code itself.
SuSE, a German company that both Intel and IBM have small minority stakes in, does this by offering IBM's customers peace of mind. According to SuSE's Geck, that peace of mind comes in the form of a "single throat to choke if something goes wrong." In addition to making sure that Linux is running smooth as silk on all of IBM's platforms, SuSE also makes sure that IBM's customers don't mistakenly move their Linux installations out of lockstep with what's supported by companies like Oracle and SAP. "Considering the pace at which changes, patches, etc. become available for Linux, that's easy to do" says Geck. "We make sure that users don't suddenly find themselves in a situation where they are running enterprise applications on uncertified versions of Linux -- a situation which would void their support." Essentially, SuSE is providing a set of very controlled high-end Linux versions that are guaranteed not to upset the production environments relying on them.
So, does that clear things up? Is that the sort of strategy and flexibility you're looking for from a technology partner like IBM? Or are you waiting to see if Linux gets more traction in the datacenter before considering it? Talkback or write to me at david.berlind@cnet.com and let me know what you think.
