Abstract: To address the requirements described above, the present invention discloses a method, apparatus, article of manufacture, and a locking structure for supporting parity protected RAID in a clustered environment. When updating parity, the parity is locked so that other nodes cannot access or modify the parity. Accordingly, the parity is locked, read, generated, written, and unlocked by a node. An enhanced protocol may combine the lock and read functions and the write and unlock functions. Further, the SCSI RESERVE and RELEASE commands may be utilized to lock/unlock the parity data. By locking the parity in this manner, overhead is minimized and does not increase as the number of nodes increases.