Messages in this thread | | | Date | Mon, 21 Jul 97 20:14:11 MDT | From | (Colin Plumb) | Subject | Soft metadata updates paper w/code |
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Looking at reiserfs, I found a University of Michigan tech report on "soft updates" a technique to remove all synchronous writes from a file system yet maintain fsck-less crashes.
(By always marking data in use before it's used and ensuring that data is not used before it's marked free, a crash can leave some blocks or inodes missing from the free map, and inodes with reference counts too high, so fsck is a good idea for garbage collection in case of a crash, but it's very optional - you can bring up the system read/write and only suffer a little bit of "leaked" disk space.)
The code is heavily fuzzed where SYSV ufs internals are concerned to avoid trade secret problems, but it's just replaced by stubs with english descriptions of what they do.
I'm not saying that "somebody oughta", because if so, then *I* oughta, but in case this is of interest to anybody, the URL is http://www.pdos.lcs.mit.edu/~ganger/papers/CSE-TR-254-95/ -- -Colin
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