Let's say that you ran the health checks on your cluster and received data_replication_check failure, what does it mean and how do you fix it? 

The NCC health check data_replication_check helps to ensure that the customers are not impacted by an extremely rare condition which can result in the inability to restore from snapshots. This issue is covered in Field Advisory 28.

Scenario 1 - Cluster is running an old version of AOS.
Scenario 2 - Cluster was recently upgraded, but has snapshots created before the AOS upgrade.

For a full explanation and the solution for both scenarios check out the health check documentation at: KB-2089.

To make sure that the issue is resolved you can run the dedicated health check for this component by connecting to a CVM and running: "ncc health_checks data_protection_checks protection_domain_checks data_replication_check" 

Note: This health check has been retired from NCC 3.9.3.