This book is about Unix architecture internals. If you would like to familiarize yourself with the most advanced topics of processes, kernel and CPU life, this book is definitely for you. The text is complex but does a great job in addressing many fundamental questions. Reading this book is a serious business. You need to mark the pages and google a lot to stay on top of it. The effort is very rewarding and would give you a deep understanding of what going on the boxes under your responsibility.
Please keep in mind that this book is not an introduction to Linux and may be an overkill if your job involves just basic day to day administration.
I would also recommend this publication if you would like to start C Programming as it gives you a very good insight on Unix/Linux internals.
My copy of this book was published in 2003. Therefore, it's an old book but most of the concepts are still valid. Looking forward for a new edition. Count me in!