Abstract: A data storage device having, for example, a disk array comprising a plurality of independent disks, an array controller for controlling the array and an auxiliary memory device connected to the disk array and array controller for temporarily storing data being moved within the array or being changed from a first data storage type to a second data storage type within the array.

Abstract: A data storage device having, for example, a disk array comprising a plurality of independent disks, an array controller for controlling the array and an auxiliary memory device connected to the disk array and array controller for temporarily storing data being moved within the array or being changed from a first data storage type to a second data storage type within the array.

Abstract: A method is described for enlarging the storage capacity of a hierarchical disk array data storage system which stores data according to different levels of redundancy, or RAID levels. The method includes first mapping the physical storage space into a first virtual storage space having a plurality of RAID areas that extend across multiple storage disks in the disk array and comprise multiple stripes of segments from each storage disk. The first virtual storage space is mapped into a second virtual storage space having multiple virtual blocks. To enlarge storage capacity, one or more storage disks are added to the hierarchic disk array. To assimilate the new storage capacity, data in a selected existing RAID area is moved to another area on the disk array of equal or greater storage capacity. The mapping of the second virtual storage space to the first is updated to reflect the data movement.