A unified namespace technique provides coherent access to unstructured data across different data access protocols having different logical constructs that are stored and managed on a storage system. A control plane infrastructure operates in connection with storage services to provide support for a vast array of storage platforms including file servers of a file system and object storage servers of an object store. Metadata associated with a data access transaction is processed separately and natively by a protocol stack of a particular storage service according to a particular data access protocol. The processed metadata is stored native to the access protocol in a metadata store associated with the particular storage service and is made available to the protocol stacks of the other storage services. Processed metadata is made available to the protocol stacks via an event notification logging service implemented as a message bus. A single canonical instance of the data is maintained for all of the logical constructs served by the storage system.