US Patent 11989097 Chunk and snapshot deletions

In some examples, a system maintains mapping metadata for data in storage, the data divided into chunks, the mapping metadata comprising chunk entries mapping chunk identifiers of the chunks to storage locations, wherein the chunk identifiers are monotonically increasing as chunks are created. The system updates an epoch in response to triggering a creation of a snapshot of the data. In response to a deletion of a first chunk, the system updates a first chunk entry for the first chunk to include a creation epoch identifier and a deletion epoch identifier for the first chunk. In response to a deletion of a first snapshot of the multiple snapshots, the system uses the creation epoch identifier and the deletion epoch identifier to determine whether to remove the first chunk entry from the mapping metadata.