Patent ID: 7702853

Claim:
A method of managing a data storage system, said method comprising: providing said data storage system, said data storage system comprising multiple memory devices in multiple storage units such that each storage unit comprises n memory devices and each memory device in each storage unit belongs to a different one of n memory arrays and comprises one of a hard disk drive, a random access memory device, an optical storage device and a magnetic tape storage device, wherein said n memory arrays comprise symmetric redundant arrays and wherein n is a number greater than 1; selectively controlling powering up and powering down of said multiple memory devices, wherein said selectively controlling comprises: at any given time powering down up to half of said multiple memory devices so as to form standby memory devices and activate memory devices; and applying a symmetric code over said multiple memory devices so that all data redundantly stored in said multiple memory devices may be recovered from said active memory devices without accessing said standby memory devices; reserving storage space for write-journals in said multiple memory devices; associating said standby memory devices with corresponding write-journals on said active memory devices; providing said corresponding write-journals with a same level of protection as said standby memory devices; receiving new data; determining a target storage location for said new data; if said target location is one of said standby memory devices, writing said new data to a corresponding write-journal for said standby memory devices; and, powering back on said one of said standby memory devices and transferring said new data out of said corresponding write-journal and into said target storage location, said powering back on is performed one of on-demand, conditionally, and periodically, wherein said associating comprises one of the following: associating said standby memory devices with said corresponding write-journals such that each particular write-journal is associated with only one particular standby memory device and further such that an active memory device containing said particular write-journal is in a different storage unit as said particular standby memory device and is controlled by a different controllers than said particular standby memory, and associating said standby memory devices with said corresponding write-journals such that each particular write-journal is associated with only one particular standby memory device, such that as active memory device containing said particular write-journal is in a same storage unit as said particular standby memory device and such that each of said n memory arrays contains no more than one write-journal from any others of said n memory arrays.