This chapter has a very specific focus: upgrading the operating system of a single host. This task is deceptively simple, requiring a lot of preparation beforehand and a lot of testing afterward. The upgrade itself can be performed in many ways. The more critical the host is, the more important it is to do the upgrade correctly. This technique is a building block. Once mastered, you can move on to larger upgrade projects, such as those described in
Chapter 20.
A single tool is required to do this task successfully, no matter what OS is involved. This tool is a piece of paper that will be used to maintain a checklist. There is no excuse for not using this tool. Our publisher, Addison-Wesley, has graciously agreed to include a blank piece of paper in the back of this book for your convenience.1
Some people choose to simulate a piece of paper by using a web page, a wiki, or a spreadsheet. These high-tech solutions have many benefits, which are described later. However, the fundamental issue is the same: There is no excuse for upgrading a server without using a checklist to guide you. Grab a pencil. Let’s begin.