What is Disaster Recovery?

Disaster recovery (DR) is an area of security planning to protect an organization from the effects of a disaster – such as a cyber attack, equipment failure or natural disasters.

Recovery point objective (RPO) and recovery time objective (RTO) are two important measurements in disaster recovery and downtime. The ability to resume complete IT operations within a specific amount of time is RTO and at a specific point is RPO. For example, if an organization has an RPO of two hours, the system must back up at least every two hours. And the recovery time objective is the maximum amount of downtime an organization can handle. A shorter RTO indicates a quicker recovery time. The RPO and RTO help administrators choose optimal disaster recovery strategies, technologies and procedures.

Organizations protect against outages or information loss as a form of insurance. The cost of outages or data loss can be measured in monetary terms or as intangibles such as health and safety, market share, or reputation. Each organization has a unique risk tolerance, and it's common for different applications to have different requirements for RTO and RPO.
Companies try to back up their data on a regular schedule such as once every 24 hours. At these times they create one or more duplicate or deduplicated copies of the primary data and write it to a new disk or to a tape.
For disaster recovery purposes, a backup copy needs to be transported or replicated offsite to ensure the data is safe in the event of a disaster.
A single point of failure is a risk of data loss or system unavailability. A single device, building, metropolitan area, power grid, flood zone, or hurricane zone all represent a single point of failure. Redundancy and the distance that spans those points of failure enables disaster recovery to keep businesses and agencies in operation regardless of the cause of the unplanned outage.