US Patent 9442850 Efficient directory refresh operations in wide area file systems

Methods, apparatuses, and systems directed to reducing network traffic and processing overhead associated with directory refresh operations in wide area network file systems. In a particular implementation, the frequency of synchronization of certain directory contents information, such as security attribute information, that changes less frequently is reduced relative to other types of directory contents information that changes more frequently, such as file and folder names, last modified times, and the like. Other implementations reduce garbage collection overhead for a cached file system by deferring deletion of invalidated objects in a directory until a client application specifically identified the directory.