The Official Ubuntu Server Book - page 2
Admin 101, Security
Chapter Seven lays out everything you need to know about doing system backups. Every system administrator needs to have a backup plan, and this chapter tells you what you need to know to put one in place. Chapter Eight discusses the different server monitoring tools available and how to start using them. This can come in really handy when you have the responsibility of monitoring multiple servers.
Chapter Ten provides a considerable amount of information about the topic of fault tolerance. While this might not seem like a topic that would be of any interest to a small office system administrator, it really should be. Any time you have more than one person depending on a computer to get work done you have a need for some level of fault tolerance. At a minimum you should know how to configure the disks in a server for basic RAID.
Murphy's Law is never truer than when it comes to administering a Linux server. You can pretty much count on something happening to your machine at a time when you need it the most. That's when a book with some basic troubleshooting instructions is worth every penny you paid for it. Chapter Eleven covers the steps you should take when something goes wrong.
Chapter twelve describes what to do when you have hard system failures. It includes things like how to use Ubuntu's recovery mode to get past some of the typical boot failures. It also gives some suggestions on what to do when you need to recover a deleted file. Chapter Thirteen contains pointers on where to go if you can't find your answer in the book. It lists some of the more common methods like Ubuntu forums and IRC channels. It doesn't mention Google, but that would be too obvious.
The B&N version of the book includes a bonus chapter 14 with some additional information on basic Linux administration and an appendix with cool tips and tricks. One good measure of a book of this type is the length of the index. "The Official Ubuntu Server Book" checks in at 501 pages with 48 dedicated to the index.
List price is $39.99, but you can pick it up on the B&N site for a good bit less. It also includes a 45-day pass to an online version available through Safari.com. This book is definitely worth the money if you need a good reference to help you over the newbie Linux admin hump.