Storage systems with reduced energy consumption, methods of operating thereof, corresponding computer program products and corresponding program storage devices. Some non-limiting examples of a write method include: configuring a plurality of storage disk units such that at any given point in time there are at least two storage disk drives operating in active state in any storage disk unit; caching in a cache memory one or more write requests and generating a consolidated write request corresponding to a stripe in a RAID group; destaging the consolidated write request; and writing the destaged consolidated write request in a write out of place manner to one or more storage disk drives operating at the destage point of time in active state. Some non-limiting examples of a read method include: configuring local storage disk drives so that at any given point in time, a part of the local storage disk drives operates in low power state, wherein the local storage disk drives are operable to switch between low power state and active state; and responsive to a read request for a portion on a local storage disk drive, reading from the local storage disk drive, if active; and if the local storage disk drive is not active, enquiring if a remote mirror storage disk drive storing a copy of the portion is active, and if yes, reading from the remote mirror storage disk drive.