Memory system with hierarchic disk array and memory map store for persistent storage of virtual mapping information

摘要

A data memory system has a hierarchic disk array (11) of multiple disks (12), a disk array controller (14) for coordinating data transfer to and from the disks (12), and a RAID management system (16) for mapping two different RAID areas onto the disks (12). The RAID management system (16) stores data in one of the RAID areas according to mirror redundancy, and stores data in the other RAID area according to parity redundancy. The RAID management system (16) then shifts or migrates data between the mirror and parity RAID areas on the disks (12) in accordance with a predefined performance protocol, such as data access recency or access frequency. The data memory system also includes a memory map store (21) embodied as a non-volatile RAM. The memory map store (21) provides persistent storage of the virtual mapping information used by the RAID management system (16) to map the first and second RAID areas onto the disks (12) within the disk array (11). The RAID management system (16) updates the memory map store (21) with new mapping information each time data is migrated between mirror and parity RAID areas.