Patent ID: 7062605

Claim:
A method for initializing a storage volume comprising: making the volume XOR consistent; processing an I/O request received from an attached host system substantially in parallel with the step of making the volume XOR consistent; and storing first progress information regarding the step of making the volume XOR consistent in a non-volatile memory, wherein the step of processing further comprises: determining if the I/O request affects only portions of the volume already made XOR consistent; performing the I/O request using read-modify-write processing if the I/O request affects only portions of the volume already made XOR consistent; and performing the I/O request using read-peer-write processing if the I/O request affects any portion of the volume not already made XOR consistent, wherein the step of performing read-peer-write processing further comprises: storing second progress information in a memory indicating portions of the volume made XOR consistent by the read-peer-write processing, wherein the step of making further comprises: determining from the first progress information and from the second progress information whether a portion of the volume to be initialized has been modified by read-peer-write processing; making the portion XOR consistent using write-same logic to clear the portion if the portion has not been modified by read-peer-write processing; making the portion XOR consistent using write-parity logic to compute parity if the portion has been modified by read-peer-write processing; and updating the first progress indicator to indicate completion of making the portion XOR consistent.