Patent ID: 7188118

Claim:
A system, comprising: a storage device configured to store a plurality of files; and a file system configured to manage access to said storage device, wherein said file system is configured to: compute a compressed size of at least a portion of a given one of said plurality of files, wherein said given file includes a plurality of ordered portions; and store an indication of said compressed size in data storage corresponding to said given file, wherein said data storage comprises a named stream; wherein said file system is further configured to: store a respective plurality of compression dictionaries in said named stream, wherein each said respective compression dictionary corresponds to one of said ordered portions; detect a write operation to a given one of said ordered portions of said given file; in response to detecting said write operation, invalidate the respective compression dictionaries corresponding to said given ordered portion and any higher-ordered portions than said given ordered portion of said given file; and subsequent to said invalidating, recompute a respective compressed size of only said given ordered portion and any higher-ordered portions than said given ordered portion of said given file.