Oracle Data Guard provides the management, monitoring, and automation software to create and maintain one or more standby databases to protect Oracle data from failures, disasters, human error, and data corruptions while providing high availability for mission critical applications
Data Guard's loosely coupled architecture provides optimal data protection and availability:
Database changes are transmitted directly from memory, isolating the standby from I/O corruptions that occur at the primary.
A standby database uses a different software code-path than the primary – isolating it from firmware and software errors that impact the primary database.
Oracle corruption detection insures that data is logically and physically consistent before it is applied to a standby database.
Data Guard detects silent corruptions caused by hardware errors (memory, cpu, disk, NIC) and data transfer faults, and prevents them from impacting the standby database.
A standby database is used to perform planned maintenance in a rolling fashion, minimizing downtime and eliminating the risks inherent with introducing change to production environments.
Oracle Active Data Guard 11g extends basic Data Guard functionality by allowing read-only access to a physical standby database while continuously applying changes received from the primary database. This increases performance and return on investment by offloading ad-hoc queries, Web-based access, reporting, and backups from the primary database while also providing disaster protection.