> It appears the current best practice is to weight each OSD according to it?s size (3.64 for 4TB drive, 7.45 for 8TB drive, etc). OSD’s are created with those sorts of CRUSH weights by default, yes. Which is convenient, but it’s import to know that those weights are arbitrary, and what really matters is how the weights of each OSD / host / rack compares to its siblings. They are relative weights, not absolute capacities. > As it turns out, it was not configured this way at all; all of the OSDs are weighted at 1. Are you perhaps confusing CRUSH weights with override weights? In the below example each OSD has a CRUSH weight of 3.48169, but the override reweight is 1.000. The override ranges from 0 to 1. It is admittedly confusing to have two different things called weight. Ceph’s reweight-by-utilization eg. acts by adjusting the override reweight and not touching the CRUSH weights. ID WEIGHT TYPE NAME UP/DOWN REWEIGHT PRIMARY-AFFINITY -44 83.56055 host somehostname 936 3.48169 osd.936 up 1.00000 1.00000 937 3.48169 osd.937 up 1.00000 1.00000 938 3.48169 osd.938 up 1.00000 1.00000 939 3.48169 osd.939 up 1.00000 1.00000 940 3.48169 osd.940 up 1.00000 1.00000 941 3.48169 osd.941 up 1.00000 1.00000 If you see something similar, from “ceph osd tree”, then chances are that there’s no point in changing anything since with CRUSH weights, all that matters is how they compare across OSD’s/racks/hosts/etc.. So you could double all of them just for grins, and nothing in how the cluster operates would change. — Anthony _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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