Oracle Data Guard Redo Transport: SYNC, ASYNC, and the Network Performance Equation
The redo transport configuration is the most consequential architectural decision in a Data Guard deployment. It determines the data loss exposure (RPO), the performance overhead on the primary, and the recovery point after a failover. Choosing SYNC or ASYNC without understanding the mechanics leads to either unacceptable data loss or unnecessary primary database degradation. Redo Transport Mechanisms ASYNC Transport (ARCN-based) In ASYNC mode, the primary database commits without waiting for the standby to acknowledge receipt of redo. The ARCn background process archives completed log groups and ships them to the standby. ...