3. Graceful Switchover - Central Console (GUI)
Graceful Switchover (GS) is a process which allows you to switch the roles of your Source and Destination Hosts, thereby swapping them. This can be a useful thing to do for a number of reasons, for example, if you wish to perform planned maintenance on your Source Host and therefore want the Destination Host to take over as the production host.
Step 1: Initiate the GS process by clicking the Perform Graceful Switchover button on the main page.
Step 2: Select the Configuration/DDC to work with . The source is dbv2 and the target is dbv1
Step 3: Once the desired Configuration/DDC is selected , the system will run a Log Gap Report . This is important because a Graceful Switchover can only be performed if the Archive Log Gap between your two Hosts is zero! If the log gap is more than zero, a warning message will be displayed, and you will be unable to proceed. NOTE: On RAC systems, a GS is possible when the Archive Log Gap is either 0 or 1.
If the operation is possible, clicking the Submit button  will begin the process. Please note the warning message above this button - GS is an important process, and because it swaps the roles of the Source and Destination Hosts, will completely change how your environment works. It is possible to use GS twice to again reverse your environment back to its original configuration, however, this will take a considerable amount of time. In short, please ensure you use the GS process responsibly.
Step 4: After the GS process is underway, you will be able to track it as a separate Task in the Active Task List .
Step 5: Once the GS process is complete, the Source and Destination Hosts for your chosen Configuration/DDC will switch. You can confirm this by going to the Configurations page and taking note of the Source and Destination host entries . The new source is dbv1 and the standby is dbv2