aufs (short for advanced multi-layered unification filesystem) implements a

union mount In computer operating systems, union mounting is a way of combining multiple directories into one that appears to contain their combined contents. Union mounting is supported in Linux, Berkeley Software Distribution, BSD and several of its successo ...

for

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...

file system In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

s. The name originally stood for AnotherUnionFS until version 2. Developed by Junjiro Okajima in 2006, aufs is a complete rewrite of the earlier

UnionFS Unionfs is a filesystem service for Linux, FreeBSD and NetBSD which implements a union mount for other file systems. It allows files and directories of separate file systems, known as branches, to be transparently overlaid, forming a single coher ...

. It aimed to improve reliability and performance, but also introduced some new concepts, like writable branch balancing, and other improvements – some of which are now implemented in the UnionFS 2.x branch. aufs was rejected for merging into mainline Linux. Its code was criticized for being "dense, unreadable, nduncommented". Instead,

OverlayFS In computing, OverlayFS is a union mount filesystem implementation for Linux. It combines multiple different underlying mount points into one, resulting in single directory structure that contains underlying files and sub-directories from all sou ...

was merged in the Linux kernel. After several attempts to merge aufs into mainline kernel, the author has given up.

Use

Aufs is included in

Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of D ...

"Jessie" (v8) and

Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: ''Desktop'', ''Server'', and ''Core'' for Internet of things devices and robots. All the ...

16.04 out of the box. Debian "Stretch" (v9) does not include aufs anymore, but provides a package aufs-dkms, which auto-compiles the aufs kernel module using

Dell Dell is an American based technology company. It develops, sells, repairs, and supports computers and related products and services. Dell is owned by its parent company, Dell Technologies. Dell sells personal computers (PCs), servers, data ...

's dkms. Docker originally used aufs for container filesystem layers. It is still available as one of the storage backends but is deprecated in favour of the backend which uses

. Several

Linux distribution A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading one ...

s have chosen aufs as a replacement for UnionFS, including: * Knoppix

live CD A live CD (also live DVD, live disc, or live operating system) is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading fro ...

– since the end of 2006, "for better stability and performance" *

NimbleX NimbleX is a small Slackware-based Linux distribution optimized to run from a CD, USB drive or a network environment. NimbleX has been praised for how fast it boots, as well as for its small disk footprint, which is considered surprising for ...

since version 2008. Switched simultaneously with Linux-Live * Porteus LiveCD, run fully in RAM *

Slax Slax is a LiveCD Linux distribution developed by Tomáš Matějíček and based on upstream customizable Linux distributions. Packages can be added by apt package manager or can be prepared as modules. The tagline for Slax refers to itself as " ...

(and Linux-Live scripts in general) since version 6 *

Xandros Xandros, Inc. was a software company which sold Xandros Desktop, a Linux distribution. The name Xandros was derived from the X Window System and the Greek island of Andros. Xandros was founded in May 2001 by Linux Global Partners (Will Roseman a ...

Linux distribution, available in the ASUS

Eee PC The ASUS Eee PC is a netbook computer line from Asus, and a part of the ASUS Eee product family. At the time of its introduction in late 2007, it was noted for its combination of a lightweight, Linux-based operating system, solid-state drive (S ...

model 901 *

10.04 LTS Live CD *

6.0 Live media *

Gentoo Linux Gentoo Linux (pronounced ) is a Linux distribution built using the Portage package management system. Unlike a binary software distribution, the source code is compiled locally according to the user's preferences and is often optimized for the ...

LiveDVD 11.0 *

LiveDVD 11.2 *

LiveDVD 12.0 * Salix Live via Linux-Live scripts until version 13.1.1 and via SaLT from version 13.37 *

Puppy Linux Puppy Linux is an operating system and family of light-weight Linux distributions that focus on ease of use and minimal memory footprint. The entire system can be run from random-access memory (RAM) with current versions generally taking up abou ...

versions can run fully in RAM with changes saved to disk on shutdown. For example, Slacko 5.3.3 running as a LiveCD. *

Manjaro Linux Manjaro ( ) is a free and open-source Linux distribution based on the Arch Linux operating system that has a focus on user-friendliness and accessibility. It uses a rolling release update model and Pacman as its package manager. It is develope ...

via their patched official kernels

References

External links

AuFS project homepage

A simple example
{{File systems Free special-purpose file systems File systems supported by the Linux kernel Union file systems

Use

See also

References

External links