Recovery point objective (RPO) refers to the amount of data loss a customer can tolerate, specifically the point in time to which your enterprise must be able to recover the data. Some enterprises require an RPO of “zero”. That means the enterprise cannot lose a single committed transaction in the event of a site failure; they must be able to recover the data back to the zero minute of the time of the disaster. There are implications to setting up an RPO of zero. The replication solution will require synchronous replication (explained in detail later in this section) and may impact performance of the application being replicated.

DRP SecurityAn RPO of greater than zero, for example 30 minutes, can be handled differently. An RPO of 30 minutes means the customer can tolerate losing the last 30 minutes of transactions in the event of a site failure. If the disaster

occurred at 12:00, the customer must be able to recover the data to at least 11:30 (30 minutes prior to the disaster). This can most likely be accomplished with asynchronous replication with minimal performance impact to the application. In this situation, careful planning and monitoring of the write-history log is essential to support the expected RPO.

DRP Security AuditA RPO can only be determined by their business rules and other governances of their environment. The customer must weigh the risk of data loss in a higher RPO against the cost and performance impact of a zero RPO.

Recovery time objective (RTO) refers to the amount of time it takes a customer to get their backup site up and running after a complete failure at the primary site. Most customers have an RTO of anywhere from 15 minutes to 8 hours, though the average is about 2 hours. This includes the time to failover the replicated LUNs (logical Unit Number) to the backup EVA (Enterprise Virtural Array) , recover the backup database and bring it online, and redirect any applications to the backup database server. A faster RTO can usually be accomplished by prestaging the backup site to the greatest extent possible.