Disaster Recovery and Business Continuity are completely different. They are siblings but still two separate and unique topics. Disaster Recovery is technology + process + people for IT systems. Business continuity is people + process for business functions. You can have Business Continuity without Disaster Recovery. The opposite is a total waste of money. If there is no plan for the business to recover and connect to IT systems, you are pouring money down the drain.
In addition, Disaster Recovery is not all about technology. There have been some good discussions about Recovery Point Objectives (RPO) and Recovery Time Objectives (RTO) in the industry. However, the linkages to the business functions have not thoroughly been detailed. Even large companies have issue with correlating the IT systems to business functions. In fact, one very large airline I worked with is a perfect example. They named 55 mission critical business functions. IT identified 55 mission critical applications. After some due diligence in aligning business function to applications, only 9 of the applications named by IT supported mission critical business functions and 46 mission critical business functions were not properly supported. So, there were many applications which had clusters, replication, and expensive Disaster Recovery techniques employed that did not need it.
A point of interest: Operational Recovery (commonly referred to as Backup) is a base upon which to build Disaster Recovery solutions. Again, Operational Recovery and Disaster Recovery are two separate yet related topics. You can have Operational Recovery (restoration of individual and small groups of systems and data ) without Disaster Recovery (restoration of major subsection or entire data centers of systems and data). Disaster Recovery without Operational Recovery is foolish. RTO and RPO apply to both Operational Recovery and Disaster Recovery; again, they have different context. Generally, the RTO and RPO for Operational Recovery are much shorter due to the fact that you are recovering a single server, a few servers, or set of files. Disaster Recovery RTO and RPO are much longer since the entire data center or a major portion is being recovered and synchronized (emphasize synchronized).
Operational Recovery is so called because backup is not the main purpose; recovery is. Thus, industry stereotypes put on “Backup and Recovery” are unnecessary. To build on Operational Recovery for Disaster Recovery, start with the Operational Recovery system and add replication, snap-shot + replication, and cross site clustering as appropriate when the correlation to business function is determined. Understanding your single points of failure is another point of focus once you have determined that you have the correct “list” of mission critical applications (including up-line and down-line dependencies – i.e. DNS, etc.). Unfortunately, some solutions need careful inspection to understand the impact on the entire environment (i.e. storage).