Disk array subsystem with self-reallocation of logical volumes for reduction of I/O processing loads

摘要

A disk array subsystem includes a logical volume allocation controller (3, 4, 6), which divides and reallocates data of the same logical volume LVN among a plurality of magnetic disk drive groups (12) when a magnetic disk group is added thereto. Successful logical-volume allocation can reduce the I/O processing frequency between magnetic disk drive groups, thus achieving enhanced performance of the disk array subsystem (13). <IMAGE>