In a RAID storage system, a parity value is generated. The storage system includes a RAID adapter, a plurality of disk array processors managing corresponding sets of RAID storage drives, and a connecting fabric. The RAID adapter initiates a parity generation operation, parallel instructions are dispatched for the array processors to each generate a partial parity value from data blocks on drives on respective managed RAID storage drives, the partial parity value is received in the RAID adapter from each array processor, and the partial parity values are combined in the RAID adapter to generate a complete parity value. The parity value may be an actual parity block to be stored on a hard disk drive or may be a reconstructed data block in the event of a failed drive.