Definition: Business Continuity is a succession of disaster recovery, aimed at allowing an organization to function during a disaster or within 1-hour after a disaster, rather than simply being able to recover after a disaster – specifically related to server availability.
It is our opinion many vendors blur the true definition in order to claim that their product provided business continuity. For True Business Continuity, vendors must provision failover servers in the event of a disaster.
Each moment an application has lost availability, you can translate the problem directly into lost revenues. Vendors different solutions will help you overcome disasters and database or application server failures by continuously replicating and synchronizing critical servers to either local or remote Business Continuity Servers (BCS). When a server goes down for most any reason, a BCS will be available to take its place and allow you and your organization to just keep working.
There are two primary options for Business Continuity Servers. The choice between a local BCS and a remote BCS basically comes down to a cost vs. value determination.

Local (Onsite) Business Continuity Servers – for organizations that can accept up to an hour of disruption to their operations due to a failed application.
Pro: Typically much less expensive than a remote solution
Con: Disruption of up to one hour to your operations.