Patent ID: 7650480
Filing Date: 2010-01-19
Classification: G06F

Abstract:
1. A storage system comprising: a plurality of flash disks, each having a plurality of slots, wherein each of the slots comprises a plurality of flash memory units, and wherein each of the flash memory units comprises a plurality of sectors; a management table for hierarchically managing a write life of each flash memory unit on a sector basis; and a controller for hierarchically distributing write-processing to the flash memory units according to the management table, wherein the controller is a RAID (Redundant Array of Independent Disks) controller, wherein the controller distributes, on a sector basis, write-processing to one flash memory unit, wherein when the write lives for each sector in that one flash memory unit are balanced, the controller then distributes, on a sector basis, write-processing to one slot, wherein when the write lives for each sector in that one slot are balanced, the controller then distributes, on a sector basis, write-processing to one flash disk, wherein when the write life of a write destination, which is a first flash disk of a plurality of flash disks, exceeds a specified threshold, the controller migrates data in the first flash disk to a migration destination, which is a second flash disk of the plurality of flash disks whose write life is less than the specified threshold, and the controller writes data that was originally intended for the first flash disk to the second flash disk, and wherein the controller selects the second flash disk as the migration destination based on priority, an empty disk being given a highest priority, and when there is no empty disk, the priority is given to a disk belonging to the same RAID group as the first flash disk and to which data has been written a small number of times.