Spring 2012 Module 19 File System Summary Ed Lazowska lazowskacswashingtonedu Allen Center 570 2012 Gribble Lazowska Levy Zahorjan 2 UFS Hardware Device inodes ID: 616500
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CSE 451: Operating SystemsSpring 2012Module 19File System Summary
Ed Lazowska
lazowska@cs.washington.edu
Allen Center 570Slide2
© 2012 Gribble, Lazowska, Levy, Zahorjan2UFS
Hardware Device
inodes
data blocksSlide3
© 2012 Gribble, Lazowska, Levy, Zahorjan3FFS
Low throughput addressed by:
larger blocks
cylinder groups
aggressive caching
hardware awarenessSlide4
© 2012 Gribble, Lazowska, Levy, Zahorjan4JFS
Journal
+
some
file system
…
Start t
Alloc inode 1067
Write inode 1067 w/
[data]
Write block 22731 w/
[data]
Commit t
….
Example: file creation
Main
memory
cache
App
requests
If data block updates are not
journaled, after a crash files may
have garbage blocks
Long post-crash boot times addressed by:
transactional journal of changes
propagated back to “real” file system asynchronously
(To be clear: FS and FFS have a cache too – I just didn’t draw it.)Slide5
© 2012 Gribble, Lazowska, Levy, Zahorjan5LFS
file1
Segments
file1
file 2
inode maps
Main
memory
cache
Write throughput addressed by:
the file system is a logSlide6
© 2012 Gribble, Lazowska, Levy, Zahorjan6Supporting Multiple File Systems: vfs