As explained, RDS provides high availability via Multi-AZ. To set up Multi-AZ, RDS needs to be configured for two things, the availability zone where the slave RDS instance will be launched and instantiated and enable the Multi-AZ option for the current RDS service:
- From the RDS dashboard navigation pane, click on Subnet Groups. Select default and click on the Edit button:
- The two Availability Zones as per the architecture diagram are us-west-2a and us-west-2c. Hence, click on the Remove button against the us-west-2b AZ. Click on the Edit button:
- You should see the following screen. Click on the default hyperlink to the view subnet details:
- Make sure that the two AZs are correctly listed as shown:
- From the RDS dashboard navigation pane, click on Instances. Select the a1ecommerce database instance and click on Modify from the Instance actions drop-down menu:
- Select Yes from Multi A-Z Deployment drop-down menu. This will instantiate slave database instance in the us-west-2c Availability Zone:
- Scroll down the page and click on the Continue button:
- Make sure that you check the Apply Immediately checkbox; if not, your changes will be scheduled for the next maintenance cycle. Click on the Modify DB Instance button:
- At this stage, you will see the Status as modifying:
- After a few minutes, you should see the status as available:
