Oracle replication for failover
We are planning a Oracle data replication (using Veritas VVR or Sun SNDR) between a primary and secondary site. The application is Web-enabled and the users access the application/database through the Internet. In case of failure of the primary site, how will the users get automatically routed to the secondary site so that services can continue without any downtime?
This depends primarily on how the Internet users currently access the application. Without knowledge of your environment and supporting infrastructure, it can be assumed that if users access the application via a URL and DNS, it should be practically seamless to the users provided the IP address of the secondary (backup) system is same as the failed system. It this context, the procedure is not much different from when an application is migrated to a new server as part of an upgrade.
Some vendors offer replication and synchronization products that can replicate Oracle data remotely and take care of client connectivity updates in the event of a failover. XOsoft comes to mind but there are other products available. That said, many of these products include a high availability component that may need to be considered as part of your current plans.
There are also failover-capable network appliances that can help with automatically rerouting network traffic to an alternate location. However, this implies that the network redirection device is not affected by the outage.
This was first published in August 2005