I am dealing with Mongoid, carrierwave and gridFS to store my uploads. For example, I have a model Article, containing a file upload(a picture). class Article include Mongoid::Document field :title, :type => String field :content, :type => String mount_uploader :asset, AssetUploader end But I would like to only store the file once, in the case where I'll upload many times the same file for differents articles. I saw GridFS has a MD5 checksum. What would be the best way to prevent duplication of identicals files ? Thanks