Disk array apparatus and disk array apparatus controlling method

摘要

Times at which requests for a data read or data write from/to a logical volume are received are stored in memory as access times of a RAID group making up the logical volume. When a predetermined time has elapsed after the access time, a number of the hard disk drives according to the redundancy of the RAID group are set to a power saving mode. Assume there are first hard disk drives and second hard disk drives having shorter lifes and the RAID group exceeds a predetermined time after the access time. When the RAID group consists of only the first drives, a number of the first drives according to the redundancy of the RAID group are set to a power saving mode and when it consists of only the second drives, an arbitrary number of second drives are set to a power saving mode.