To create an Amazon Aurora instance, you first create a DB cluster or one or more instance and includes a shared cluster volume that store the data for all instances in the cluster – all instances attach to the same volume shared.
An Amazon Aurora cluster volume is a virtual database storage volume that spans multiple Availability Zones, with each Availability Zone having a copy of the cluster data.
An Amazon Aurora DB cluster consists of two different types of instances:
- One and only one primary instance where all the writes and updates happen – yes you can read too but the main focus is writing data in the primary instance.
- Amazon Aurora Replicas – these are secondary instances that supports only read operations. Each DB cluster can have up to 15 Amazon Aurora Replicas in addition to the primary instance. Amazon Aurora Replicas, distribute the read workload among various instances, increasing performance. Amazon Aurora Replicas also support in multiple Availability Zones to increase your db availability. 15 replicas Aurora instances is 3x the number allows by the RDS MySQL service.
Note: Aurora is MySQL compatible and can be manipulated with the same toolset used on MySQL – MySQL Workbench and MySQL Shell