An illustrative “open archive” architecture relieves the immediate need to add network-attached storage (NAS) devices to a storage management system. The open archive architecture provides streamlined access to live production data, which originally was stored on a NAS device but which is archived to secondary storage to free up NAS space. An open-archive server coordinates with an open-archive layer that operates on the NAS device. The open-archive server identifies data sets on the NAS that meet archiving criteria, which are then automatically moved to an open archive in secondary storage. The open archive layer intercepts data-access calls coming into the NAS device, e.g., open calls, read calls, write calls. The intercepted calls are reported to the open-archive server for analysis. If the open-archive server determines that the data referenced in an intercepted call is stored in the open archive, the open-archive server initiates a restore job that recovers the data from secondary storage and stores it back on the NAS device. The intercepted call may now be served from the NAS. These operations occur automatically and do not involve users or their computing devices, and the computing devices operate without data agents for the NAS-based data.