Method and system for minimizing writes and reducing parity updates in a raid system

A system in a data storage system for updating stored data with received data in a cache associated with said data storage system, where said data storage system comprises N data storage drives, where data and calculated parity are striped across said N data storage drives, where a stripe comprises a plurality of data sectors on each of said N data storage drives, said system comprising:

• a cache associated with said data storage system for receiving data for updating stored data in said data storage system;
• means for determining if said received data in said cache includes all sequential data sectors contained within a complete stripe within said data storage system;
• means for calculating parity for said complete stripe by:
• calculating a range of sectors between which all sectors received into said cache for said complete stripe fall,
• reading from said N data storage drives into said cache only said sectors within said range of sectors which are not included in said received data in said cache for said complete stripe, and
• logically combining said plurality of sectors in said cache for said complete stripe, such that input/output operations within said data storage system are minimized.

A program product for updating stored data with received data in a cache associated with a data storage system, where said data storage system comprises N data storage drives, said program product comprising:

• a data processing system usable medium;
• and
• a data updating program encoded within said data processing system usable medium that, in response to receiving data into said cache,
• determines if said received data in said cache includes all sequential data sectors contained within a complete stripe within said data storage system, and
• calculates parity for said complete stripe by:
• calculating a range of sectors between which all sectors received into said cache for said complete stripe fall;
• reading from said N data storage drives into said cache only said sectors within said range of sectors which are not included in said received data in said cache for said complete stripe;
• and
• logically combining said plurality of sectors in said cache for said complete stripe, such that input/output operations within said data storage system are minimized.