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Information About

Fossil (file System)





FEATURES

Important features include:
  • Snapshots are available to all users. No administrator intervention is needed to access old data. (This is possible because Fossil enforces file permissions; users can only access data which they would be allowed to access anyway; thus a user cannot snoop on another's old files or look at old passwords or such.)

  • Data in snapshots cannot be modified. Only the non-permanent snapshots (so called archives) can be removed.


To access a snapshot, one would connect to a running fossil instance (“mount” it) and change directory to the desired snapshot, e.g. ''/snapshot/yyyy/mmdd/hhmm'' (with ''yyyy'', ''mm'', ''dd'', ''hh'', ''mm'' meaning year, month, day, hour, minute). To access an archive (permanent snapshot), a Directory of the form ''/archive/yyyy/mmdds'' (with ''yyyy'', ''mm'', ''dd'', ''s'' meaning year, month, day, sequence number) would be used. Plan 9 allows modifying the Namespace in advanced ways, like ''redirecting'' one path to another path (e.g. ''/bin/ls'' to ''/archive/2005/1012/bin/ls''). This significantly eases working with old versions of files.


HISTORY

Fossil was designed and implemented by Sean Quinlan , Jim McKie and Russ Cox at Bell Labs and added to the Plan 9 distribution at the end of 2002. It became the default file system in 2003, replacing Kfs and the previous Plan 9 archival file system, dubbed ''The Plan 9 File Server'', or " Fs ". Fs is also an archival file system which originally was designed to store data on a WORM optical disc system. The permanent storage for fossil is provided by Venti, which typically stores data on hard drives, which have much lower access times than optical discs.


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