Patent ID: 7051156

Claim:
A method of read/write operation in a RAID-5 configured storage system having a RAID controller, a RAID cache memory, a plurality of physical disks, and one or more logical disks, the method comprising: reading data from said logical disk; writing data to said logical disk, wherein the writing process comprises: (i) reading an old data block and an old parity block from said logical disk or said RAID cache; (ii) forming a new parity block and a new data block by computing an XOR with the new data and the old data block and the old parity block; (iii) updating the logical disk by placing the new data block and the new parity block in the RAID cache or the logical disk by: (a) finding a buffer of a physical disk number and a physical block number in the RAID cache memory by a search algorithm; (b) allocating in the RAID cache memory a buffer area in the case when the physical disk number and the physical block number cannot be found; and (c) writing data to the allocated buffer area and setting the allocated buffer area as a dirty buffer in the RAID cache memory; flushing data from said cache memory to said logical disk when the RAID controller is idle; and otherwise performing read/write operations under the control of the RAID controller to the RAID cache memory.