US Patent 7516286 Conversion between full-data and space-saving snapshots

A method, system, computer system, and computer-readable medium that enable a copy of data to be converted from a full-data snapshot to a space-saving snapshot, or vice versa, while retaining all the contents of the snapshot. Full-data snapshots can be used for efficient read operations and off-host processing operations. Space-saving snapshots can be used to store multiple copies of primary data in a minimum amount of storage space without consuming unnecessary storage space to store duplicate copies of data that are not changing. The ability to convert between full-data and space-saving snapshots enables organizational storage, backup, and recovery needs to be met using the best type of snapshot for a given operation.