1. A storage library complex in communication with a host system, the storage library complex comprising: a plurality of storage library systems, each storage library system being logically interconnected with the other storage library systems, and each storage library system defining a physically distinct environment that comprises: a plurality of storage media resources; a plurality of media drive resources that operate to perform input/output functions on the storage media resources; a local memory that operates to store a partition definition that identifies which of the plurality of storage media resources and which of the plurality of media drive resources from across the plurality of storage library systems are presently assigned to each of a plurality of complex-wide partitions; and at least one processor that operates to: receive a request from a host system involving requested resources of at least one of the storage library systems, the requested resources comprising at least one of storage media resources or media drive resources from the plurality of storage library systems; query the partition definition according to the request to determine which of the plurality of complex-wide partitions include the requested resources; and communicate a response to the host system according to which of the plurality of complex-wide partitions are determined to include the requested resources.