Recovery Point Objective
Recovery Point Objective (RPO) is a measure of how much data can be lost were a disaster to occur. RPO refers to the point in time in the past to which you will recover.
When designing a replication solution, the RPO generally drives the replication mode chosen and the sizing of the links used for replication. If the primary system fails and a failover occurs, the RPO is a worst case measurement.
RPO = 0 means there is no data loss as a result of a disaster. It is the best result with synchronous replication.
RPO = 2 minutes is the best result with asynchronous streaming replication.
RPO = 10 minutes is the best result with asynchronous periodic replication. For an RPO over 10 minutes, use asynchronous periodic replication.
For example, a disaster hits at 2:00 pm. After recovery operations at the disaster recovery site complete, an RPO of two hours would guarantee that all transactions that were committed up to and including 12:00 pm would be present in the replicated copy of a database. The RPO could, in fact, contain transactions committed after 12:00 pm but the defined two-hour RPO guarantees transactions committed up to 12:00 pm will always be present.