Promoting a disaster recovery instance to a primary instance lets you quickly resume read and write operations in a disaster recovery scenario. This operation is necessary if the region of the primary instance is unavailable or if high data latency prevents a switchover. After the promotion, the data synchronization link between the two instances is broken. The original disaster recovery instance and the original primary instance then run as separate, independent instances.
Prerequisites
The status of the disaster recovery instance group must be Running.
Notes
Before you promote a disaster recovery instance, monitor the data latency between the primary instance and the disaster recovery instance. For more information, see View replication performance.
Promoting the disaster recovery instance can cause the loss of data that has not yet been synchronized from the primary instance. Carefully evaluate the business risks before you perform this operation.
After you promote the disaster recovery instance, you must assess your services. To connect to the new primary instance, change the connection address in your application to the connection address of the new primary instance and configure the network settings between the application and the new primary instance. For example, you may need to set an IP whitelist or check network connectivity.
Procedure
Go to the Global Distributed Cache page.
On the Global Distributed Cache page, click the instance ID of the target instance group.
In the RDS Instance List section at the bottom of the page, find the disaster recovery instance. In the Actions column for that instance, click Promote To Primary Instance.
Read the information about the effects of the promotion. Click Promote To Primary Instance again. During the promotion:
Disaster recovery instance group: The group remains, and its status is Running. However, it will contain only the newly promoted primary instance.
Original disaster recovery instance: This instance becomes the primary instance of the group. Its status changes from Deleting Replication Link to Running. The instance switches to read/write (RW) mode and runs as an independent RDS for SQL Server instance.
You can view the instance on the Instances page. Make sure to switch to the destination region.
Original primary instance: This instance is removed from the disaster recovery instance group. However, it continues to run as an independent RDS for SQL Server instance. Its data is preserved, its connection is not interrupted, and access is not affected.
You can view the instance on the Instance List page. Make sure to switch to the destination region. If you no longer need the original primary instance, you can release or unsubscribe from the instance. After an instance is released or unsubscribed from, it no longer incurs charges.
Data synchronization link: After the promotion, the data synchronization link between the instances is broken. You will no longer be charged for data synchronization.
Related operations
You can add a disaster recovery instance to the new primary instance to deploy a new off-site disaster recovery system.
You can delete a disaster recovery instance group when it contains only a primary instance. This operation deletes only the group. The primary instance continues to run, and its accounts and data are preserved.
To delete the group: Go to the Global Distributed Cache page. In the Actions column, click Delete. Read the instructions, and then click OK.