System and method for parity caching based on stripe locking in raid data storage

A method for performing multiple input/output (I/O) operations to a storage medium organized as a redundant array of independent disk (RAID) devices with a stripe of data storage defined across a plurality of devices and a parity block associated with each stripe comprising:

• selectively locking and unlocking the stripe in response to a current I/O operation request thereto so that only one I/O operation can proceed within the stripe while the stripe is locked and until the stripe is unlocked;
• storing, in a first parity buffer associated with a previous I/O operation, parity data derived from an XOR operation performed to first old data in the stripe, first old parity data of the stripe and first new data, all associated with the previous I/O operation, to be written to the stripe;
• providing a second parity buffer associated with the current I/O operation;
• swapping the first parity buffer with the second parity buffer before the step of selectively locking and unlocking unlocks the stripe to enable the current I/O operation to proceed;
• writing second new data associated with the current I/O operation to the stripe;
• and
• writing parity data derived from an XOR operation performed to second old data in the stripe, second old parity data of the stripe and the second new data, all associated with the current I/O operation, to the stripe when no next I/O operation request, subsequent to the current I/O request to the stripe is present.

A computer-readable medium, including program instructions for a computer, for performing multiple input/output (I/O) operations to a storage medium organized as a redundant array of independent disk (RAID) devices with a stripe of data storage defined across a plurality of devices and a parity block associated with each stripe, the program instructions performing the steps of:

• selectively locking and unlocking the strip in response to a current I/O operation request thereto so that only one I/O operation can proceed within the strip while the strip is locked and until the stripe is unlocked;
• storing, in a first parity buffer associated with a previous I/O operation, parity data derived from an XOR performed to first old data in the strip, first old parity data of the stripe and first new data, all associated with the previous I/O operation, to be written to the stripe;
• swapping the first parity buffer with a second parity buffer before the step of selectively locking and unlocking unlocks the stripe to enable the current I/O operation to proceed;
• writing second new data associated with the current I/O operation to the strip;
• and
• writing parity data derived from an XOR operation performed to second old data in the stripe, second old parity data of the stripe and the second new data, all associated with the current I/O operation, to the stripe when no next I/O operation request, subsequent to the current I/O request to the stripe is present.