The filemd5 command returns the md5 hash for a single file stored using the GridFS specification. Client libraries use this command to verify that files are correctly written to MongoDB. The command takes the files_id of the file in question and the name of the GridFS root collection as arguments.

Drivers MUST NOT run the 'filemd5' database command to confirm that all chunks were successfully uploaded. We assume that if none of the inserts failed then the chunks must have been successfully inserted, and running the 'filemd5' command would just be unnecessary overhead and doesn't work for sharded chunk keys anyway.