Oracle 11g Data Guard and RAC
Data Guard is Oracle's true Disaster Recovery (DR) solution and answer to customers who require uptime and zero data loss for their mission-critical data center environments.
Oracle Data Guard has been around for a long time--since version 8 of the Oracle database server when it was first called Oracle Physical Standby database. It evolved into Data Guard in Oracle 9i release. Since 9i and 10g, many new enhancements have been incorporated into the Data Guard solution to optimize performance and availability as well as to ease maintenance of the Data Guard operations. In a nutshell, Data Guard implements a physical or logical copy of the primary database at a remote standby site that can be used to failover or switchover to the standby database server on the remote site in the event of a disaster or planned maintenance operation. Data Guard ships redo logs from the primary database to the standby database and applies the redo to the standby site.
