Both Tom Adelstein and Bill Lubanovic has done an extraordinary work to put together Linux System Administration. Tom is not just a system administrator but a good technical writer.
Generally most Linux classes and books cover topics such as user administration, setting up mail and web servers, printers, new hard disk / file system etc. But very few books or classes deals with scalability and availability issues. The book teaches you how to setup a reverse proxy in front of Apache, setting up a load balancing server, hot backups and running Linux based server 24/7."