Abstract: A method and system are provided for improving efficiency of storing and accessing data blocks for systems that are limited to small size, host accessible data blocks, such as having a maximum size of 512 bytes, by allowing larger size subsystem data blocks to be created from the smaller size logical data blocks. A host command is analyzed to determine whether the host accessible logical data block aligns with the larger subsystem block. If so, the larger block(s) is(are) sent to the host. If the command does not align, the larger block is processed into a plurality of segments so that the addressed data block(s) can be aligned, and any error correction coding verified. The present invention allows a subsystem to store and manage efficiently sized blocks of data while still supporting a host's need to access smaller, single architecturally defined addressable blocks.

Abstract: A system incorporating the invention stores data on communicating disk drives in such a manner as to enable recovery of the data in the event a failure of one of the disk drives. The system includes a first disk drive and a second disk drive, both for storing compressed data records in compressed track formats. Each compressed data record includes a CRC value. A cache stores compressed tracks of data records that are read from the first disk drive and a CRC value is calculated for each stored track of compressed data records. That CRC value is appended to the compressed track. A switch is coupled between the cache, a host processor and the second disk drive for dispatching and receiving tracks of compressed data records between the first disk drive and the second disk drive.