The recovery time objective (RTO) is the maximum tolerable length of time that a computer, system, network, or application can be down after a failure or disaster occurs.
The RTO is a function of the extent to which the interruption disrupts normal operations and the amount of revenue lost per unit time as a result of the disaster. These factors in turn depend on the affected equipment and application(s). An RTO is measured in seconds, minutes, hours, or days and is an important consideration in disaster recovery planning (DRP).
Numerous studies have been conducted in an attempt to determine the cost of downtime for various applications in enterprise operations. These studies indicate that the cost depends on long-term and intangible effects as well as on immediate, short-term, or tangible factors. Once the RTO for an application has been defined, administrators can decide which disaster recovery technologies are best suited to the situation. For example, if the RTO for a given application is one hour, redundant data backup on external hard drives may be the best solution. If the RTO is five days, then tape, recordable compact disk (CD-R) or offsite storage on a remote Web server may be more practical.