[ceph-users] precise/best way to check ssd usage

Currently I am checking usage on ssd drives with ceph osd df| egrep 'CLASS|ssd' I have a use % between 48% and 57%, and assume that with a node failure 1/3 (only using 3x repl.) of this 57% needs to be able to migrate and added to a different node. Is there a better way of checking this (on old Nautilus)?