A method for redundant array of independent disks (RAID) consistency initialization. The method allows fast RAID creation of the RAID subsystem and the RAID is capable of accepting I/O access after completion of the RAID creation. The method comprises the steps of: setting a RAID configuration, creating an initialization progress table (IPT) for storing the progress states of the initialization of the RAID, and writing the IPT and the RAID configuration into a non-volatile memory device. After that, the RAID can accept I/O access and meantime a consistency initialization can be performed according to the IPT. In one example, the consistency initialization comprises a consecutive initialization mechanism consecutively progressing in background mode and an induced consistency initialization mechanism induced by an I/O accessing to the RAID.

A storage controller, when writing n sets of data into a first storage device, adds dummy data to other sets of data except for a first set of data having a largest size among the n sets of data such that sizes of other sets of data become equal to the size of the first set of data, calculates (n1) parities based on the first set of data and the other sets of data, and when reading the n sets of data from the first storage device, concurrently performs a processing of reading a second set of data having a smallest size among the n sets of data from the first storage device and a processing of restoring each of two or more sets of data in the n sets of data except for the second set of data, by using the (n1) parities and the dummy data.