Redundant storage with mirroring by logical volume with diverse reading process

摘要

A mirrored memory for a data processing system. The memory system includes two device controllers and related disk drives for storing the mirrored data. Each of the disk drives is divided into logical volumes. Each device controller contains a plurality of reading processes and a correspondence table that establishes the reading process to be used in retrieving data from the corresponding disk drive. Each disk controller responds to a read command that identifies the logical volume by using the correspondence table to select the appropriate reading process and by transferring data from appropriate physical storage device containing the designated logical volume.