Abstract: A computing system includes a processor having an operating system executing thereon, a storage system having one or more storage media, and a controller coupled between the processor and the storage system. The controller maintains partition data defining one or more partitions for the storage media in response to commands received from the operating system, and controls access to the storage media in accordance with the partition data. The controller selects a subset of the partitions as active partitions, and communicates to the operating system a portion of the partition data that defines the active partitions. The controller may, for example, select the subset based on a current authenticated user. The controller intercepts storage access requests from the processor, and rejects storage accesses requests that are not directed to the active partitions.