Methods and structure for initializing a RAID storage volume substantially in parallel with processing of host generated I/O requests. Initialization of a RAID volume may be performed as a background task in one aspect of the invention while host generated I/O requests proceed in parallel with the initialization. The initialization may preferably the performed by zeroing all data including parity for each stripe to thereby make each stripe XOR consistent. Host generated I/O requests to write information on the volume may utilize standard read-modify-write requests where the entire I/O request affects information in a portion of the volume already initialized by background processing. Other host I/O requests use standard techniques for generating parity for all stripes affected by the write requests. These and other features and aspects of the present invention make a newly defined RAID volume available for host processing is quickly as possible.