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Re: ext3 and chattr +S on postfix spools

Wietse Venema:
> maildir delivery requires that certain file system operations are
> atomic and synchronous.
> Translated into ext3 speak that means: the link and unlink operations
> are written to the log before the respective system call returns.

Stephen C. Tweedie:
> Synchronous IO is *always* guaranteed to be persistent on disk on
> return, and ext3 also makes firm atomicity guarantees about all
> deletes, renames etc.

Are the default mount options of ext3fs such that link() and rename()
are synchronous?

If not, what hoop jumping do you recommend?  Is fsync() on an open
file guaranteed to take care of all a file's directory entries or
is that only an accidental artefact of ext3 implementation that
might go away in a future version?

>  (Incidentally, ffs does not --- renames across
> directories are not atomic on ffs.)

ffs rename promises that the file won't end up in lost+found.
That is good enough for Postfix.

maildir users can chattr their personal maildir.


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