A storage system includes a RAID adapter, disk array switches, sub-processors, and hard disk drives. A disk-related operation is initiated in the RAID adapter which dispatches a command to a disk array processor (or sub-processor) in an enclosure for the processor to perform the operation on one or more drives. The adapter may dispatch the command to a processor in a single enclosure through a disk array switch or to processors in multiple enclosures through switches in upstream enclosures. The adapter is then free to perform other functions. The processor commences the specified operation on one or more selected drives. Upon completion of the operation, the results are transmitted by the processor and received by the adapter. Offloading the task to the distributed sub-processors reduces the burden on the RAID adapter, reduces system bandwidth usage, and enables access to other drives to be maintained.