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aufs (short for advanced multi layered unification filesystem) implements a union mount for Linux file systems.

Developed by Junjiro Okajima in 2006,[1] aufs is a complete rewrite of the earlier UnionFS. It aimed to improve reliability and performance, but also introduced some new concepts, like writable branch balancing,[2] and other improvements – some of which are now implemented in the UnionFS 2.x branch.

The name is acronym which originally stood for AnotherUnionFS, but since version 2 it stands for "advanced multi layered unification filesystem".


Several Linux distributions have chosen aufs as a replacement for UnionFS, including:

Known problems[edit]

aufs seems to have problems with some underlying file systems, notably Btrfs.[8]

See also[edit]


  1. ^ History of the Aufs project maintained by Junjiro Okajima
  2. ^ Goals and new features of aufs in the project's homepage
  3. ^ Knoppix release note explaining the switch from Unionfs to aufs.
  4. ^ Linux Live scripts use AUFS for better stability
  5. ^ "Gentoo Linux - Gentoo Linux - LiveDVD 11.0". 2011-03-08. Retrieved 2012-04-19. 
  6. ^ "Gentoo Linux - Gentoo Linux releases 11.2 LiveDVD". 2011-08-07. Retrieved 2012-04-19. 
  7. ^ "Gentoo Linux - Gentoo Linux releases 12.0 LiveDVD". 2012-01-02. Retrieved 2012-04-19. 
  8. ^ "Btrfs rm issue · Issue #2961 · dotcloud/docker · GitHub". Retrieved 2014-05-04. 
  9. ^ RAMboot using syslinux

External links[edit]