A method is used in managing truncation of files of file systems. A request is received to delete a portion of a file of a file system. A replica of the file is created. The replica represents a state of the file at a particular prior point in time. The replica shares a set of file system blocks of the file with the file. The portion of the file is deleted by updating metadata of the file. The replica of the file is asynchronously deleted in background by de-allocating the set of file system blocks.