Abstract: A data storage and retrieval system is provided which has extremely high capacity. The system includes a large array of small disk files, and three storage managers for controlling the allocation of data to the array, access to data, and the power status of disk files within the array. The allocation manager chooses the disk files upon which incoming data is written based on the current state of the disk files (active or inactive), the available capacity, and the type of protection desired (i.e. unprotected, RAID, mirrored, etc.). The access manager interprets incoming read requests to determine the location of the stored data. The power manager sequences disk files between active and inactive to provide the storage requested by the access and allocation managers.