While the MDM manages the configuration, the Storage Data Server (SDS) is the component responsible for the actual aggregation of raw storage and the management of data persistence.

Role of SDS: The SDS software runs on every node that contributes storage. It takes ownership of the local physical drives (NVMe, SSD, HDD), aggregates them, and presents them as part of a Storage Pool.

Data Handling: The SDS performs the heavy lifting of writing data to disk, reading data for clients (SDCs), and ensuring data consistency. It manages the 'Mesh Mirroring' by communicating with other SDSs to replicate chunks of data. Without the SDS, the physical drives are just isolated disks; the SDS aggregates them into a cohesive software-defined storage layer.