On Mon, Jul 8, 2019 at 1:02 PM Lars Marowsky-Bree <lmb@xxxxxxxx> wrote: > > 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. How does that pool manage with the same client pattern but 3x replication? The difference between 4kB and 4MB writes could be many things. -- dan > > > 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 > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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