Le 13/08/2018 à 15:55, Jason Dillaman a écrit : > > > > so problem seems located on "rbd" side ... > > > That's a pretty big apples-to-oranges comparison (4KiB random IO to > 4MiB full-object IO). With your RBD workload, the OSDs will be seeking > after each 4KiB read but w/ your RADOS bench workload, it's reading a > full 4MiB object before seeking. >
yes you're right, but if we compare cluster to cluser, on new cluster, rados bench is faster (2 times) rbd fio is 7 times slower. that's why I suppose rbd is th problem here, but I really do not understand how to fix it. I looked at 3 old hammer cluster and two new luminous/buestore clusters and those results are constants. I do not think ceph decided to put bluestore as default luminous filestore if random reads are 7 time slower ;) (BTW: thanks for helping me Jason :) ).
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