Disaster recovery, business continuity and business impact analysis are closely related, but significantly different concepts that all fit into dealing with a disaster. Because the terms are so frequently used and not always clearly distinguished, it is worth keeping the difference in mind.
Disaster recovery is the process of getting storage and other systems back up and running in the event of a disaster. It is a relatively undifferentiated term in that the aim of disaster recovery is to get everything back to where it was before the disaster struck.
Business continuity focuses on keeping the business operating. Where disaster recovery tends to deal with systems and data, business continuity is concerned with overall business operations. Typically business continuity involves prioritizing various business processes and recovering the most important ones first. Thus, disaster recovery is likely to be concerned with getting the entire storage network back up while business continuity is more likely to work on getting the parts dealing with critical processes like transaction processing back first.
Business impact analysis supports business continuity by attempting to decide which processes are the most critical to recover in case of a disaster. This usually involves assigning monetary value to the protection of assets involved in specific business processes.
Storage Technology discusses these processes in a technical note at: http://www.storagetek.com/solutions/bus_continuity/.
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.