Explanation/Reference: https://www.dellemc.com/de-de/documentation/unity-family/unity-p-configure-nfs-file-sharing/03- unity-nfs-c-ch-configuring-file-systems.htm

Explanation
The keystore is tied to the storage processors, so care must be taken when performing service operations in
order to preserve the encryption keys. In the event that the chassis and both storage processors need to be
replaced, both storage processors should not be replaced at the same time. Instead, the chassis replacement
should be followed while retaining one SP until the array is back online before replacing the second SP. In the
case that storage processors have already been replaced at the same time and the keystore was lost, the
keystore may be restored from an external backup.

Explanation
Recovery Point Objective (RPO) is an industry accepted term that indicates the acceptable amount of data, measured in units of time, that may be lost in a failure. When you set up an asynchronous replication session, you can configure automatic synchronization based on the RPO. You can specify an RPO from a minimum of
5 minutes up to a maximum of 1440 minutes (24 hours).
References: https://www.emc.com/dam/uwaem/documentation/unity-p-replication-config.pdf (page 7)