On Fri, Jan 15, 2010 at 6:12 PM, nixlists <nixmlists@gmail.com> wrote:
quoted text
> qmail's author says "Queue reliability demands that single-byte writes
> be atomic. This is true for a fixed-block filesystem such as UFS, and
> for a logging
> filesystem such as LFS."

I hope that doesn't mean what I interpret it to mean, because if you
write one byte to the beginning of a file and one byte to the end of a
file, there's no guarantee which byte hits the disk first.  The other
interpretation of it, meaning that you won't ever write half a byte,
is true, but strikes me as exceptionally obvious and true of every
filesystem.

So what does it mean for a single byte write to be atomic?