AWS CloudHSM cluster high availability and load balancing

When you create an AWS CloudHSM cluster with more than one HSM, you automatically get load balancing. Load balancing means that the AWS CloudHSM client distributes cryptographic operations across all HSMs in the cluster based on each HSM's capacity for additional processing.

When you create the HSMs in different AWS Availability Zones, you automatically get high availability. High availability means that you get higher reliability because no individual HSM is a single point of failure. We recommend that you have a minimum of two HSMs in each cluster, with each HSM in different Availability Zones within an AWS Region.

For example, the following figure shows an Oracle database application that is distributed to two different Availability Zones. The database instances store their master keys in a cluster that includes an HSM in each Availability Zone. AWS CloudHSM automatically synchronizes the keys to both HSMs so that they are immediately accessible and redundant.