In the case of both, businesses need to consider two performance measures, Recovery Point Objective (RPO) and Recovery Tim Objective (RTO). RPO is a measure of how many hours or minutes of data the company is willing to accept it can lose. So, for example if you are performing a full backup to tape daily, implicit in that is a RPO of one working day because if a server failed at the end of a working day before that night’s backup were run you would lose a whole day's work.

RTO is a measure of how long a delay the organisations is willing to tolerate in getting data available and services back-up and running after a failure or disaster. With traditional tape based backup this might be days by the time a server is replaced or repaired, then the operating system and backup software installed, then the data restored from tape.

Whilst protecting against different threats, Disaster Recovery and High Availability measures work in a similar way. A live server’s configuration and data are continuously replicated to a replica. The continuous replication means that RPO is minimised, and the existence of the replica server means that RTO is minimised too.