Exchange-aware VSS backups are supported for both the active and passive storage groups and databases. The passive copy backup solution we provide is VSS-only, and it is implemented by the Exchange Replica VSS Writer that is part of the Replication service. Streaming backups are only supported from the active storage groups. You cannot use streaming backup APIs to back up the replica database. A VSS backup program must be used with a VSS Requestor for the Exchange writer.