Union mount: Difference between revisions
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Union mounts are implemented by a union filesystem such as [[UnionFS]] and [[AUFS]]. They originated with [[Plan 9 from Bell Labs#Union directories|Plan 9]] and its concept of ''union directories''.<ref name="lwn4"/> |
Union mounts are implemented by a union filesystem such as [[UnionFS]] and [[AUFS]]. They originated with [[Plan 9 from Bell Labs#Union directories|Plan 9]] and its concept of ''union directories''.<ref name="lwn4"/> |
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<ref name="usenix">{{Cite journal|title=Union Mounts in 4.4BSD-Lite|journal=Proceedings of the USENIX Technical Conference on UNIX and Advanced Computing Systems|date=December 1995|first=Jan-Simon|last=[[Pendry]]|coauthors=[[Marshall Kirk McKusick]]|volume=|issue=|pages=25–33|id= |url=http://www.usenix.org/publications/library/proceedings/neworl/full_papers/mckusick.a|format=|accessdate=25 November 2007 }}</ref> |
<ref name="usenix">{{Cite journal|title=Union Mounts in 4.4BSD-Lite|journal=Proceedings of the USENIX Technical Conference on UNIX and Advanced Computing Systems|date=December 1995|first=Jan-Simon|last=[[Pendry]]|coauthors=[[Marshall Kirk McKusick]]|volume=|issue=|pages=25–33|id= |url=http://www.usenix.org/publications/library/proceedings/neworl/full_papers/mckusick.a|format=|accessdate=25 November 2007 }}</ref> |
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Revision as of 18:23, 8 March 2012
A union mount is a mount that allows several filesystems to be mounted at one time, appearing to be one filesystem.[1]
Rather than mounting each filesystem at a different place in the directory hierarchy, a union mount overlays the filesystems, creating a unified hierarchy. Thus, any given directory (or "folder") in the resulting filesystem may contain files and subdirectories from any or all of the underlying filesystems.[2][3][4][5]
Generally one of the filesystems will be mounted read-write, while other filesystems are mounted read-only. Union mounts are implemented by a union filesystem such as UnionFS and AUFS. They originated with Plan 9 and its concept of union directories.[6]
References
- ^ Pendry, Jan-Simon (December 1995). "Union Mounts in 4.4BSD-Lite". Proceedings of the USENIX Technical Conference on UNIX and Advanced Computing Systems: 25–33. Retrieved 25 November 2007.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Wright, Charles P. "Versatility and Unix Semantics in a Fan-Out Unification File System". Stony Brook University Technical Report FSL-04-01b. Retrieved 25 November 2007.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Aurora, Valerie (March 2009). "Unioning file systems: Architecture, features, and design choices". lwn.net. Retrieved 21 December 2009.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Aurora, Valerie (March 2009). "Union file systems: Implementations, part I". lwn.net. Retrieved 21 December 2009.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Aurora, Valerie (April 2009). "Unioning file systems: Implementations, part 2". lwn.net. Retrieved 21 December 2009.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Blunck, Jan (May 2009). "VFS based Union Mount (V3)". lwn.net. Retrieved 21 December 2009.
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