US Patent 11860746 Resilient data storage system with efficient space management

A storage system has a plurality of storage nodes having equal non-volatile storage capacity that is subdivided into equal size cells. Host application data that is stored in the cells is protected using RAID or EC protection groups each having members stored in ones of the cells and distributed across the storage nodes such that no more than one member of any single protection group is stored by any one of the storage nodes. Spare cells are maintained for rebuilding protection group members of a failed one of the storage nodes on remaining non-failed storage nodes so full data access is possible before replacement or repair of the failed storage node.