Storage system with rebuild operations

A storage system comprising a plurality of storage devices and a processor,

• wherein each of a plurality of stripe rows comprises a predetermined number of data elements including a plurality of data and at least two redundant data for the plurality of data,
• wherein the processor is configured to:
• store each of the predetermined number of data elements in different storage devices of the plurality of storage devices, and
• dispersively store, in the plurality of storage devices, a plurality of data elements included in the plurality of stripe rows, wherein the number of the plurality of storage devices is greater than the predetermined number, such that stripes rows are composed of unique combinations of physical storage devices, and
• wherein when at least one storage device in the plurality of storage devices fails, the processor is configured to rebuild a data element, which is stored in the failed storage device, in a stripe row with a low redundancy level prior to rebuilding a data element in a stripe row with a redundancy level higher than the low redundancy level, on the basis of data elements in storage devices other than the failed storage device among data elements in the stripe row with the low redundancy level.