https://docs.openstack.org/api-ref/shared-file-system/#share-replicas-since-api-v2-11

Share replicas are the replicated copies of the existing share. You can use Share Replicas to sync data so that each share replica has an identical copy of the same share. Share replication can be used as a disaster recovery solution or as a load sharing mirroring solution.

Manila supports replication of shares between different storage pools. These pools may be on different back-end storage systems or within the same back end, depending upon the replication style chosen, the capability of the driver and the configuration of back ends. To ensure that a secondary copy is scheduled to a distinct back end, you must specify the availability_zone attribute.

More details: https://docs.openstack.org/manila/latest/contributor/share_replication.html