File system unification using LatticeFS

Abstract

LatticeFS is a namespace unification system designed to merge multiple source file systems into a single working file system. atticeFS can be used to merge multiple software package directories, work with multiple file systems as if they are one, and share a single storage medium among multiple machines. On a high level, LatticeFS takes as input an arbitrary number of file system paths, and mounts a new virtual drive that will appear to the user as a union of the input file systems. Of course, attempting to combine multiple file systems will inevitably be met with conflicts. Situations in which multiple input file systems contain files/directories with the same name will be common in large systems; which file/directory should the user be exposed to in this case? Previous work such as UnionFS solved the problem by giving each input file system a strict priority value, and when a conflict occurred, the file/directory with the highest priority was the one shown to the user. In LatticeFS, we have introduced a plug-in system in which different strategies for resolving conflicts can be easily swapped in and out; additionally, handlers for special file types can also be "plugged" into the system. This paper describes and evaluates all aspects of LatticeFS in detail.