On 2019-07-08T12:25:30, Dan van der Ster <dan@xxxxxxxxxxxxxx> wrote:
> Is there a specific bench result you're concerned about?
We're seeing ~5800 IOPS, ~23 MiB/s on 4 KiB IO (stripe_width 8192) on a
pool that could do 3 GiB/s with 4M blocksize. So, yeah, well, that is
rather harsh, even for EC.
> I would think that small write perf could be kept reasonable thanks to
> bluestore's deferred writes.
I believe we're being hit by the EC read-modify-write cycle on
overwrites.
> FWIW, our bench results (all flash cluster) didn't show a massive
> performance difference between 3 replica and 4+2 EC.
I'm guessing that this was not 4 KiB but a more reasonable blocksize
that was a multiple of stripe_width?
Regards,
Lars
--
SUSE Linux GmbH, GF: Felix Imendörffer, Mary Higgins, Sri Rasiah, HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde
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