Distributed Caching and High Availability
While ECP recovery handles interrupted application server connections to the data server, the application servers in a distributed cache cluster are also designed to preserve the state of the running application across a failover of the data server. Depending on the nature of the application activity and the failover mechanism, some users may experience a pause until failover completes, but can then continue operating without interrupting their workflow.
Data servers can be mirrored for high availability in the same way as a stand-alone InterSystems IRIS instance, and application servers can be set to automatically redirect connections to the backup in the event of failover. (It is not necessary or even possible to mirror an application server, as it does not store any data.) For detailed information about the use of mirroring in a distributed cache cluster, see Configuring ECP Connections to a Mirror.
The other failover strategies detailed in Failover Strategies for High Availability can also be used in a distributed cache cluster. Regardless of the failover strategy employed for the data server, the application servers reconnect and recover their states following a failover, allowing application processing to continue where it left off prior to the failure.
