Disclosed are a redundant data storage system (e.g., a RAID system) and a method of operating such a redundant data storage system that provides significant power savings with minimal reduction in reliability. The system and method allow up to half of the memory devices in any of the memory arrays in the system to be placed in standby without significantly impacting the read accesses. The system and method further designate reserved areas in the active memory devices as write-journals, which have at least the same level of protection as the main arrays. The write-journals allow data to be written without powering up a standby memory device. Thus, power consumption is minimized without impacting reliability.