10 spring 2013 file is renamed to a hidden name done

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Unformatted text preview: there is no “directory” –  Read locks on /home and /home/user –  Write lock on /home/user/foo •  Read lock prevents a directory from being deleted 2/14/13 9 Colorado State University, Sangmi Pallickara CS480 Principles of Data Management Spring 2013 Garbage collection in GFS •  Ader a file is deleted, GFS does not reclaim space immediately November 8th, 2012 CS480 Principles of Data Management Master logs a file’s deletion immediately L24.10 Spring 2013 •  File is renamed to a hidden name •  Done lazily during garbage collec4on at –  Includes dele4on 4mestamp –  File and chunk levels •  Master scans the file system namespace –  Delete if hidden file existed for more than 3 days •  When file removed from namespace –  In memory metadata is also removed –  Severs links to all its chunks! November 8th, 2012 L24.11 November 8th, 2012 L24.12 2 2/15/13 CS480 Principles of Data Management Spring 2013 Garbage collection: When Master scans its chunk namespace CS480 Principles of Data Management Spring 2013 The role of heart-beats in garbage collection •  Chunk server reports subset of chunks it currently has •  Iden4fies orphaned chunks –  Not reachable from any file •  Master replies with...
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