I have seen this and some of our big customers have also seen this. I was using 8TB HDDs and when running small tests using a fresh HDD setup, these tests resulted in very good performance. I then loaded the ceph cluster so each of the 8TB HDD used 4TB and reran the same tests. performance was cut in 1/2. This is using the default settings on how ceph creates the dirs and sub-directories on each OSD. You can flatten out this dir structure so the structure is more wide than deep and performance is improved. Check out the filestore_merge_threshold and filestore_split_multiple settings. Rick > On Jul 20, 2016, at 3:19 PM, Kane Kim <kane.ist...@gmail.com> wrote: > > Hello, > > I was running cosbench for some time and noticed sharp consistent performance > decrease at some point. > > Image is here: http://take.ms/rorPw <http://take.ms/rorPw> > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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