Patent ID: 7743276

Claim:
A method for restoring redundancy, lost due to a mass-storage-device failure or failures within a component data-storage system of a distributed data-storage system comprising a number of component data-storage systems, each component data-storage system containing a number of mass-storage devices, the method comprising: when sufficient free data-storage space is available within the component data-storage system in which the mass-storage-device failure or failures occurred, restoring data-storage units of segments and/or segment portions that were stored on the failed mass-storage device or devices; when sufficient free data-storage space can be made available within the component data-storage system in which the mass-storage-device failure or failures occurred by moving one or more numbers of segments and/or segment portions from the component data-storage system to other component data-storage systems of the distributed data-storage system, moving the one or small number of segments and/or segment portions from the component data-storage system to other component data-storage systems and then restoring data-storage units of remaining segments and/or segment portions that were stored on the failed mass-storage device or devices; and otherwise, moving segments and/or segment portions that were stored on the failed mass-storage device or devices to other component data-storage systems of the distributed data-storage system.