Multistep recovery employing erasure coding in a geographically diverse data storage system

Abstract

Multistep recovery of chunk fragments of a peer group employing hierarchical erasure coding for geographically diverse data storage protection is disclosed. A peer group of chunks can employ zone-level erasure coding of chunks that can each employ chunk-level erasure coding. In a first iteration, fragment recovery can be performed across peer group chunks based on the zone-level erasure coding. Subsequently, the first iteration can perform recovery of other fragments within a chunk based on the chunk-level erasure coding. Where additional fragments are to be recovered, subsequent iterations can be performed. The disclosed multistep recovery can enable recovery of fragments that would typically have been considered unrecoverable via conventional techniques. Additionally, multistep recovery can enable recovery of fragments across a peer group of chunks that can be more computing resource efficient than recovery of chunks across the peer group of chunks.