I recently learned that 'MAX AVAIL' in the 'ceph df' output doesn't represent what I thought it did. It actually represents the amount of data that can be used before the first OSD becomes full, and not the sum of all free space across a set of OSDs. This means that balancing the data with 'ceph osd reweight' will actually increase the value of 'MAX AVAIL'. Knowing this I would like to graph both 'MAX AVAIL' and the total free space across two different sets of OSDs so I can get an idea how out of balance the cluster is. This is where I'm running into trouble. I have two different types of Ceph nodes in my cluster. One with all HDDs+SSD journals, and the other with all SSDs using co-located journals. There isn't any cache tiering going on, so a pool either uses the all-HDD root, or the all-SSD root, but not both. The only method I can think of to get this information is to walk the CRUSH tree to figure out which OSDs are under a given root, and then use the output of 'ceph osd df -f json' to sum up the free space of each OSD. Is there a better way? Thanks, Bryan _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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