Chapter 2. Backing It All Up

In Chapter 1, we looked at disaster recovery as a whole. The nuts and bolts of backup and recovery are but a small part of the overall disaster recovery picture. Before we begin looking at the details of how to perform certain types of backups, let’s look at backups in general.

Don’t Skip This Chapter!

The casual reader might assume that this chapter is an introduction to basic backup concepts. While that is, in fact, the purpose of this chapter, it is also true that many seasoned administrators are unfamiliar with the ideas presented here. One reason for this is that administrators find themselves constantly being pulled away from “mundane” activities like backups for things that are thoughtto be more “important”—like installing new servers and figuring out why the systems are running slowly. Also, many administrators may go several years without ever needing a restore. (The need to use your backups on a regular basis would undoubtedly change your ideas about their importance.)

I wrote this book because backups (and recoveries) have been my primary area of emphasis for several years, and I would like to share the lessons I’ve learned from this focused activity. This chapter provides an overview of how your backups should work. It also explains many basic, yet extremely important, concepts upon which any good backup plan should be based and upon which any implementation discussed in this book will be based.

There are many stories in this book, like the one in the following sidebar. Each is a true story that really happened to someone I know. These are not urban legends or horror stories passed on from admin to admin. These are firsthand encounters with disaster. Why is that important? Each story makes a point, and it was not just made up to make that point. The things that I warn about in this book really happen. This can be a very tough job if you are not prepared, so read closely.

Why the Word “Volume” Instead of “Tape”?

Most backup utilities were written originally to back up to tape, and most people do back up to tape. Therefore, most books and manpages talk about backing up to tape. However, many people are backing up to CDs or magneto-optical disks. These media types have many advantages, since they act more like disk drives than tape drives. Random access of backup data is easier, and you can read them using any block size you wish, since they do not record interrecord gaps as tape drives do.[2]

Since many people are no longer using tape, this book will use the more generic word "volume” whenever appropriate. You’ll also find the term “backup drive” instead of “tape drive.” Again, that is because the backup drive could be a CD burner, especially if you’re a Linux user. The book uses the words “tape” and “tape drive” only when they are necessary and appropriate.

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