Multi-AZ deployments for high availability - Amazon Relational Database Service
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Multi-AZ deployments for high availability

Multi-AZ deployments can have one standby or two standby DB instances. When the deployment has one standby DB instance, it's called a Multi-AZ DB instance deployment. A Multi-AZ DB instance deployment has one standby DB instance that provides failover support, but doesn't serve read traffic. When the deployment has two standby DB instances, it's called a Multi-AZ DB cluster deployment. A Multi-AZ DB cluster deployment has standby DB instances that provide failover support and can also serve read traffic.

You can use the Amazon Web Services Management Console to determine whether a Multi-AZ deployment is a Multi-AZ DB instance deployment or a Multi-AZ DB cluster deployment. In the navigation pane, choose Databases, and then choose a DB identifier.

  • A Multi-AZ DB instance deployment has the following characteristics:

    • There is only one row for the DB instance.

    • The value of Role is Instance or Primary.

    • The value of Multi-AZ is Yes.

  • A Multi-AZ DB cluster deployment has the following characteristics:

    • There is a cluster-level row with three DB instance rows under it.

    • For the cluster-level row, the value of Role is Multi-AZ DB cluster.

    • For each instance-level row, the value of Role is Writer instance or Reader instance.

    • For each instance-level row, the value of Multi-AZ is 3 Zones.