Summary: Powerful FUSE UNION filesystem which gives fine control over how reads/writes are distributed, and allows underlying mounts/settings to be changed at runtime without remounting (using "magic" xattrs)
Summary: mergerfs is a union filesystem for FUSE. It allows to join multiple source directories, declare priority mappings for file operations, to provide a joined view to the underlying files. It's similar to mhddfs, unionfs, and aufs; but allows for accessing standard and extended attributes.