Ask three different people what their idea of a disaster is and you’ll probably get three different answers. For most administrators, the term disaster probably means any scenario in which one or more essential systems, services, or applications cannot operate and the prospects for quick recovery are less than hopeful—that is, a disaster is something a service reset or system reboot won’t fix.

To ensure that operations can be restored as quickly as possible in a given situation, every network needs a clear disaster recovery plan. In this chapter, I’m not going to mince words and try to explain why you need to plan for disasters. Instead, I’m going to focus on what you need to do to get ready for the inevitable, because worst-case scenarios can and do happen. I’m also going to discuss predisaster preparation procedures.