Patent ID: 7836250

Claim:
A method for operating a data storage system that includes a plurality of mass storage memory disks that are configured to store data redundantly, the method comprising: storing in the data storage system a first mapping between a given logical address, a primary mass storage memory disk, and a secondary mass storage memory disk; storing in the primary mass storage memory disk a second mapping between the given logical address, a physical address within the primary mass storage memory disk, and the secondary mass storage memory disk; configuring the data storage system to use the first mapping to direct a read request for data stored at the given logical address to the primary mass storage memory disk and not to the secondary mass storage memory disk; determining a characteristic service level of one or more of the mass storage memory disk; defining a reduced service level, which is less than the characteristic service level; and performing the following steps automatically, without intervention by a human operator: detecting the reduced service level on the primary mass storage memory disk in the data storage system; in response to detecting the reduced service level, rebalancing read requests using the second mapping to divert the read request for the data from the primary mass storage memory disk to the secondary mass storage memory disk, while servicing previously received read requests, previously received write requests, and currently received write requests in the primary mass storage memory disk at the reduced service level; wherein for each mass storage memory disk, write requests are stored in a first queue only including write requests and read requests are stored in a second queue only including read requests; wherein detecting the reduced service level comprises determining that the second queue for the primary mass storage memory disk includes an amount of read requests greater than a predetermined amount of read requests.