Preface

Both the Linux and the mainframe communities are understandably interested in the unique concepts and benefits of Linux on the mainframe. In this book, we define mainframe as being IBM's enterprise servers, that is, S/390 and zSeries servers.

This guide is for anyone seeking technical or market insight regarding Linux on the mainframe. It is for the business person who looks for opportunities to consolidate servers, reduce the complexity of an infrastructure, or reduce IT costs. It is also written for the IT architect who wants to plan for, design, and implement the solutions. It is for all those who are interested in this solution.

This book gives an overall perspective of the concepts that make this solution unique. It is a practical guide which helps you to reach an informed decision as to whether Linux on the mainframe is for your business. It shows examples of business solutions for Linux on the mainframe, and examples of how systems can be designed and built.

While this book is not a tutorial or how-to book, it references a wealth of material that provides details about specific technical topics.

Part 1, "Linux on the Mainframe an Introduction," describes technologies that possess inherent, strong values on their own merits so that they should be considered as options for your IT projects. This part includes an introduction to Linux, an introduction to the mainframe, and an introduction to Linux on the mainframe.

Part 2, "Planning for Linux," discusses the early decision points that allow a Linux on the mainframe solution to effect the bottom-line project value. Apart from these decision points, this part illustrates, with the help of two sample companies, the spectrum of possibilities open to you. It also presents a total cost-of-ownership discussion on how Linux on the mainframe can facilitate substantial savings in the enterprise.

Part 3, "Is Linux on the Mainframe for Me?" is about the technical foundations that bring unique value to running applications in a Linux-on-the-mainframe environment. Virtualization, communications, and security are among the topics discussed. For example, this part describes how it is possible to have hundreds of Linux servers on one mainframe machine.

Part 4, "Making the Most of Linux on the Mainframe," is about the challenge that Linux on the mainframe means to systems management. How can you preserve the benefits of tight systems management schemes that help to make mainframe environments so reliableand, at the same time, allow Linux to act as an engine for the rapid change that the market-place demands today? This part explores the opportunities that Linux on the mainframe offers for managing availability, data, performance, and security.

Part 5, "Running Applications," outlines the spectrum of uses for Linux images, ranging from independent servers to components in an integrated multi-platform environment with traditional mainframe operating systems. There is also a section with considerations for those who want to port applications from other platforms.

Part 6, "Reference," provides technical details about specific Linux and mainframe functions and capabilities. It also points to some of the key software that is available to your Linux-on-the-mainframe solution, including applications, middleware, and systems management and performance tools.

We have attempted to make the various topics as independent as possible, but, as with any system-level solution, all parts are interrelated. There is a fair amount of cross-referencing to allow you to find sections where a related topic is covered in more detail.

The book is the result of collaboration among three current IBM employees and one retired IBM employee. Our sources are companies that use Linux on the mainframe, customer visits, and other IBM colleagues. The book, its purpose, and structure are an outgrowth of what we have learned.