What is a Disaster Recovery?
Disaster recovery is the process, policies and procedures of restoring operations critical to the resumption of business, including regaining access to data (records, hardware, software, etc.), communications (incoming, outgoing, toll-free, fax, etc.), and other business processes after a natural or human-induced disaster.

With the rise of information technology and the reliance on business-critical information the importance of protecting irreplaceable data has become a business priority in recent years. This is especially evident in information technology, with most companies relying on their computer systems as critical infrastructure in their business. As a result, most companies are aware that they need to backup their digital information to limit data loss and to aid data recovery.

Most large companies spend between 2% and 4% of their IT budget on disaster recovery planning; this is intended to avoid larger losses. Of companies that had a major loss of computerized data, 43% never reopen, 51% close within two years, and only 6% will survive long-term.

Seven tiers of disaster recovery.
The Seven Tiers of Disaster Recovery was originally defined by Share to help identify the various methods of recovering mission-critical computer systems as required to support business continuity. The seven tiers of business continuity solutions offer a simple method to define current service levels and associated risks.