Cloud capacity scaling with high readable capacity in metadata space constrained deduplication systems

Abstract

Cloud units in cloud storage include containers including data containers storing file segments, segment tree containers storing upper-level segments of segment trees representing the files, and cloud containers storing headers from the data and segment tree containers. A header for a data container includes fingerprints identifying the file segments. A header for a segment tree container includes fingerprints identifying the upper-level segments. A storage appliance stores a first level of metadata for each cloud unit in a read-write state, a second level of metadata for each cloud unit in a read-only state, and a third level of metadata for each cloud unit in an offline state. The third level requires less storage than the first and second levels. The second level requires less storage than the first level. The limited metadata space of the appliance is managed by maintaining at least a subset of cloud units in the read-only state.