aufs
{{Short description|Linux filesystem}}
{{lowercase}}
{{distinguish|AUFS}}
{{Infobox filesystem
| name = aufs
| full_name = Advanced multi layered unification filesystem
| developer = Junjiro Okajima
| introduction_os =
| introduction_date = 2006
| partition_id =
| directory_struct =
| file_struct =
| bad_blocks_struct =
| max_filename_size =
| max_files_no =
| max_volume_size =
| max_file_size =
| filename_character_set =
| dates_recorded =
| date_range =
| date_resolution =
| forks_streams =
| attributes =
| file_system_permissions = POSIX
| compression =
| encryption =
| OS = Linux via third-party kernel module
| website = [https://aufs.sourceforge.net/ aufs.sourceforge.net]
}}
aufs (short for advanced multi-layered unification filesystem) implements a union mount for Linux file systems. The name originally stood for AnotherUnionFS until version 2.
Developed by Junjiro Okajima in 2006,{{cite web|title=History of aufs|url=http://aufs.sourceforge.net/History|access-date=2015-11-08}} 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,[http://aufs.sourceforge.net/ Goals and new features of aufs in the project's homepage] 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, [and] uncommented".{{cite web|last1=Aurora|first1=Valerie|title=Unioning file systems: Implementations, part 2|url=https://lwn.net/Articles/327738/|website=LWN.net|access-date=2015-11-08|date=2009-04-07}} Instead, OverlayFS was merged in the Linux kernel.{{cite web|url=https://github.com/torvalds/linux/commit/e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c|title=overlay filesystem · torvalds/linux@e9be9d5|website=GitHub |access-date=12 July 2016}}{{cite web|last1=Hellwig|first1=Christoph|title=Re: [RFC Aufs2 #5 28/29] export lookup functions|url=http://marc.info/?l=linux-kernel&m=123938533724484&w=2|access-date=2015-11-08|date=2009-04-10}} After several attempts to merge aufs into mainline kernel, the author has given up.{{cite web|last1=Okajima|first1=Junjiro|title=Re: [RFC Aufs2 #5 28/29] export lookup functions|url=https://marc.info/?l=linux-kernel&m=123938442923108|access-date=2018-10-01|date=2009-04-10}}
Use
Aufs is included in Debian "Jessie" (v8) and Ubuntu 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'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 {{mono|overlay2}} backend which uses OverlayFS.{{cite web|title=Deprecated Engine Features|website=GitHub |url=https://github.com/docker/cli/blob/master/docs/deprecated.md|access-date=2020-10-26}}
Several Linux distributions have chosen aufs as a replacement for UnionFS, including:
- Knoppix live CD Linux distribution – since the end of 2006, "for better stability and performance"{{cite web|title=KNOPPIX 5.1 - Live Linux Filesystem On CD|url=http://www.knopper.net/knoppix/knoppix51-en.html|publisher=knopper.net|access-date=2015-11-08|date=2013-01-05}}
- NimbleX since version 2008. Switched simultaneously with Linux-Live
- Porteus LiveCD, run fully in RAM
- Slax (and Linux-Live scripts in general) since version 6[http://www.linux-live.org/?changes Linux Live scripts] {{Webarchive|url=https://web.archive.org/web/20090322090540/http://www.linux-live.org/?changes |date=2009-03-22 }} use AUFS for better stability
- Xandros Linux distribution, available in the ASUS Eee PC model 901
- Ubuntu 10.04 LTS Live CD
- Debian 6.0 Live media
- Gentoo Linux LiveDVD 11.0{{cite web|url=http://www.gentoo.org/news/20110308-livedvd.xml |title=Gentoo Linux - Gentoo Linux - LiveDVD 11.0 |publisher=Gentoo.org |date=2011-03-08 |access-date=2012-04-19 |url-status=dead |archive-url=https://web.archive.org/web/20120413110015/http://www.gentoo.org/news/20110308-livedvd.xml |archive-date=2012-04-13 }}
- Gentoo Linux LiveDVD 11.2{{cite web|url=http://www.gentoo.org/news/20110807-livedvd.xml |title=Gentoo Linux - Gentoo Linux releases 11.2 LiveDVD |publisher=Gentoo.org |date=2011-08-07 |access-date=2012-04-19 |url-status=dead |archive-url=https://web.archive.org/web/20120417064501/http://www.gentoo.org/news/20110807-livedvd.xml |archive-date=2012-04-17 }}
- Gentoo Linux LiveDVD 12.0{{cite web|url=http://www.gentoo.org/news/20120102-livedvd.xml |title=Gentoo Linux - Gentoo Linux releases 12.0 LiveDVD |publisher=Gentoo.org |date=2012-01-02 |access-date=2012-04-19 |url-status=dead |archive-url=https://web.archive.org/web/20120421204113/http://www.gentoo.org/news/20120102-livedvd.xml |archive-date=2012-04-21 }}
- Salix Live via Linux-Live scripts until version 13.1.1 and via SaLT from version 13.37
- Puppy Linux 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 via their patched official kernels {{cite web|url=https://gitlab.manjaro.org/packages/core/linux54/blob/master/PKGBUILD |title=Manjaro linux54 kernel PKGBUILD|date=2020-01-19 |access-date=2020-01-19}}
See also
{{Portal|Free and open-source software}}
- OverlayFS, the competing project that was chosen for merger to the Linux core
- File system
- Union mount, describing the concept of merging file system branches
- UnionFS, an older union mount project
- Syslinux
References
{{Reflist}}
External links
- [http://aufs.sourceforge.net/ AuFS project homepage]
- [http://bbs.archlinux.org/viewtopic.php?pid=314698 A simple example]
{{File systems}}
Category:Free special-purpose file systems