A disaster is any unplanned interruption of computing resources that the IT director determines is unacceptable. It is purely subjective.
One hour of Web server downtime for a small business that relies completely on the Web for revenue could be devastating or cost a substantial amount of revenue.
As such, there is no one-size-fits-all approach to disaster recovery. Rather, companies need to plan for the recovery of systems first by prioritizing resources and creating backup schedules to match the maximum allowable downtime for any given server.