Information processing system with redundant storage having interleaved master storage and substorage regions

An information processing system, comprising:

• at least one processor;
• a redundant storage including at least two storage devices to be referenced by said processor respectively, both of said two storage devices storing the same data at each address of a storage area of each storage device, each of said two storage devices having a storage area divided into master storage regions and substorage regions alternately in predetermined size units of addresses;
• and
• wherein each of the master storage regions in said two storage devices are interleaved to said two storage devices and each of the substorage regions stores duplicate data of said master storage regions in a different storage device from the storage device in which the corresponding data is stored in the master storage regions.