IBM sponsored and actively participated in the port of the Linux kernel to run on the S/390. This maneuver demonstrates IBM's faith in Linux as the right choice for operating system in the open systems market. It's one thing to jump on the latest fad and advertise that your company will provide support/consulting for running Linux on its x86-based hardware, but another thing entirely to start from scratch and port the kernel to your flagship productnot to mention the icon of "closed, proprietary" systems.
Of course, this move is not some act of great altruism; indeed, it's a very strategic move for Big Blue to port Linux to run on their hardware. With applications development for MVS and family (the traditional mainframe operating systems) waning, how better to extend the support (if not sales) of these machines by providing a way to run a standards-based OSone that doesn't have a bunch of license restrictions and royalties baggage And there is a lot of big iron out there.
In addition to the activities above and mentioned earlier in this article, and more significant (yet less widely reported), is IBM's "opensourcing" (read "donation," if you ask me) of several vital filesystem components, including a journaled filesystem that will work in conjunction with Linux 2.4's logical volume manager (LVM). Many IT managers deem both of these as prerequisites to bringing Linux systems into their data centers. A journaled filesystem ensures filesystem integrity by recording all changes to the filesystem metadata to a logging partition with synchronous writes. This greatly reduces the amount of time required to check the filesystem consistency in case of a system crash. It also allows filesystems to be expanded dynamically, while the system is online.
Meanwhile, LVM allows a system administrator to create virtual disks out of pools of physical disks. These virtual disks split a single disk into many smaller partitions, or coalesce several disks to appear as a single disk. The logical volume manager also provides for functionality such as multiple copies (typically either one or two spares) of important partitions.
Although IBM's contributions have not yet become the standard filesystem toolset for Linux users, that day is not far off. As more and more IT departments start using Linux, there will be more demand for tools, and these tools will be thoroughly tested and enhanced.