According to Wikipedia, Disaster Recovery (DR) is "the process, policies and procedures . . for recovery . . . of technology infrastructure . . . after a natural or human-induced disaster."" The ability to recover quickly with minimal data loss after a disaster such as a fire, hurricane, etc., can make the difference between an organization staying in business or vanishing. In an OpenStack environment there are multiple approaches of realizing this recovery which differ in how much work is lost (the recovery point objective - RPO) and how long it takes to recover (the recovery time objective - RTO). These approaches trade-off up-front effort and cost (when there is no disaster) against greater data loss (RPO) and much longer recovery times (RTO) after a disaster. The appropriate approach depends upon the organization's objectives.