The following are my definitions for these three terms:
??? Business continuity: The process of ensuring that day-to-day activities can continue
regardless of the problem. It encompasses both technical and nontechnical
disasters, such as a worker strike or a supply-chain issue.
??? High availability: The process of ensuring that systems remain available as long as
possible no matter what the cause might be for downtime. This includes disasters,
but it also includes events such as regular maintenance, patches, and hardware
migration.
??? Disaster recovery: The process of mitigating the likelihood of a disaster and the
process of returning the system to a normal state in the event of a disaster.
Figure 1-1 shows the relationship between the three terms.
Figure 1-1. The relationship between business continuity, high availability, and
disaster recovery
CHAPTER 1 n WHAT IS DISASTER RECOVERY? 3
Remember, the result of failed disaster recovery projects is often massive scope creep
and communication chaos. In the following sections are some specific examples of such
failures, taken from real situations that I??™ve either faced or helplessly witnessed.
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