Abstract: A method, and apparatus for recovering cache data of a failed redundant storage controller and reestablishing redundancy by mirroring cache data of a primary cache memory of a first storage controller in a secondary cache memory of another storage controller. Upon a failure occurring in a storage controller, the failure is detected and, in response, a structured list of cache tags is created in the controller where having the secondary cache that is the mirror of the primary cache of the failed controller.

Abstract: A RAID 0 disk array has an optimizing algorithm for allocating the amount of data stored to each drive in a disk array. The algorithm allocates a proportion of the data for each stripe to the various disk drives based at least in part on the data transfer rate for each drive. The disk array may be constructed such that about half of the disk drives write to the outside tracks of the drives while the remaining disks write to the inside tracks. Using the algorithm, the minimum data transfer rate for the disk array may be maximized.

Abstract: Performance and reliability as a disk array system can be always kept optimal even when a group construction of disk drives is changed. The disk array system is connectable to a host and includes a plurality of drives, input/output control portions for controlling data input/output between the host and the drives, a plurality of paths for connecting the drives and the input/output control portions and modules each accommodating a predetermined number of drives. When the number of the drives is increased or decreased, other drives or modules connected to paths different from the paths connected to the drives to be increased or decreased are displayed. When the number of the drives is increased or decreased, other drives accommodated in modules different from the modules accommodating the drives to be increased or decreased are displayed.