Details: Oracle ACFS Replication Unplanned Failover

This page explains how to implement ACFS Replication Unplanned Failover.

Oracle ACFS replication failover provides unplanned failover where the standby location assumes the role of the primary in case of failure.

The acfsutil repl failover command reverses the role of a replication standby location so it becomes a replication primary location, or optionally terminates the replication relationship. The failover command insures that the standby location contains an exact copy of the results of the last successful replication transfer. If necessary, the command restores the location back to its state as of that transfer.

The acfsutil repl failover command behaves differently based on the scenario in which it was run:

  • Both the standby location and corresponding primary location are operating normally.

    In this scenario, the command reverses the replication relationship. There is no data loss. Note that failover fails in this case if replication is paused. To allow this case to succeed, run the acfsutil repl resume command.

  • The primary location is not currently available, but you want to wait until it is back online.

    In this scenario, the command verifies the status of the replication primary. If the primary is not accessible and the timeout period has expired (if specified), then the command restores the standby location to its state as of the last successful replication transfer and converts it into a replication primary. Some data loss is possible, for example if there was a transfer in process when the primary location became unavailable. When the original primary location becomes available, it is aware that the failover command has been run and converts itself into a replication standby location.

  • The primary location is not currently available and you do not want to wait until it is back online.

    In this scenario, the command verifies the status of the replication primary. If the primary is not accessible and the timeout period has expired (if specified), then the command restores the standby location to its state as of the last successful replication transfer and converts it into a replication primary. Some data loss is possible, for instance if there was a transfer in process when the primary location became unavailable. After the failover command has been run, you have two options: A new standby location can be configured using the acfsutil repl update command. Alternatively, you can terminate replication by running acfsutil repl terminate primary on the new primary.