Looking at the blog, I notice he disabled the write cache before the
tests: doing this on my m550 resulted in *improved* dsync results (300
IOPS -> 700 IOPS) still not great obviously, but ... interesting.
So do experiment with the settings to see if you can get the 840's
working better for you.
While you can't do much about the endurance lifetime being a bit low,
you could possibly improve performance using a journal *file* that is
located on the 840's (you'll need to symlink it - disclaimer - have not
tried this myself, but will experiment if you are interested). Slightly
different open() options are used in this case and these cheaper
consumer SSD seem to work better with them.
Regards
Mark
On 18/12/14 18:08, Alexandre DERUMIER wrote:
what to you mean by "not playing well with D_SYNC"?
Hi, check this blog:
http://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/
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