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application level write ordering guarantees?



Hi, can someone tell me whether applications can expect the write
requests they make to be executed in order?  For instance, suppose an
application requests that a file be deleted, and then that another
file be moved to an unrelated place.  Will these events always happen
in that order?  Or to put it another way, if something unexpected
happens in the meantime (say the computer crashes), is it guaranteed
that just the second action won't have been performed (i.e. that the
second action was done first and the crash happened just after that)?

    How about if a file is written (and closed) and then a different
file is moved?  Is it possible that the second file gets moved before
all the data is written?

    Does this depend on the file system or do all/most filesystems
behave the same way?  Sorry if this is common knowledge, but I googled
for a while and couldn't find anything.  If it matters, I am trying to
make sure a backup program (see http://rdiff-backup.stanford.edu)
doesn't lose data.  Thanks for any information.


-- 
Ben Escoto





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