US Patent 11216199 Applying deduplication digests to avoid same-data writes

A technique for managing write requests in a data storage system checks whether newly-arriving data match previously-stored data that have been recorded in a deduplication database. If a match is found, the technique compares mapping metadata for the newly-arriving data with mapping metadata for the matching data. If both sets of metadata point to the same storage location, then the newly-arriving data is a same-data write and a new write to disk is avoided.