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Re: fsync, ext3, raid (md) 1, write barriers and PATA caching

Bruno Wolff III wrote:
On Mon, Dec 11, 2006 at 11:14:52 -0500,
  Ric Wheeler <ric emc com> wrote:
You can always do a sanity test on the barrier by timing how many synchronous files/sec you can create (i.e., create/write/fsync/close). Speeds vary depending on what kind of drive you have, journal mode, etc, but you will always see much faster times with the barrier off than on while writing small files (say 10K).

That's probably a good idea in any case. Down the road I will be interested
in whether barriers work through encrypted file systems and this will be a good
test to have available.

I should get at most 120 commits per second if write barriers are working;
so I think that should be easy to detect.

Is there already a tool out there that does this? It shouldn't be hard to
write something simple, but maybe someone has written something fancy

I will send you the test code that I use & some test runs,


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