Amazon Relational Database Service
User Guide (API Version 2014-10-31)

Managing a Multi-AZ Failover

You do not need to set up a AWS CloudHSM Classic HA partition group for your standby DB instance if you are using a Multi-AZ deployment. In fact, the details of a failover are handled automatically for you. During a failover, the standby instance becomes the new primary instance and the HSM continues to work with the new primary instance.