Hi Ceph users, I have a Ceph 16.2.7 cluster that so far has been replicated over the `host` failure domain. All `hosts` have been chosen to be in different `datacenter`s, so that was sufficient. Now I wish to add more hosts, including some in already-used data centers, so I'm planning to use CRUSH's `datacenter` failure domain instead. My problem is that when I add the `datacenter`s into the CRUSH tree, Ceph decides that it should now rebalance the entire cluster. This seems unnecessary, and wrong. Before, `ceph osd tree` (some OSDs omitted for legibility): ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF -1 440.73514 root default -3 146.43625 host node-4 2 hdd 14.61089 osd.2 up 1.00000 1.00000 3 hdd 14.61089 osd.3 up 1.00000 1.00000 -7 146.43625 host node-5 14 hdd 14.61089 osd.14 up 1.00000 1.00000 15 hdd 14.61089 osd.15 up 1.00000 1.00000 -10 146.43625 host node-6 26 hdd 14.61089 osd.26 up 1.00000 1.00000 27 hdd 14.61089 osd.27 up 1.00000 1.00000 After assigning of `datacenter` crush buckets: ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF -1 440.73514 root default -18 146.43625 datacenter FSN-DC16 -7 146.43625 host node-5 14 hdd 14.61089 osd.14 up 1.00000 1.00000 15 hdd 14.61089 osd.15 up 1.00000 1.00000 -17 146.43625 datacenter FSN-DC18 -10 146.43625 host node-6 26 hdd 14.61089 osd.26 up 1.00000 1.00000 27 hdd 14.61089 osd.27 up 1.00000 1.00000 -16 146.43625 datacenter FSN-DC4 -3 146.43625 host node-4 2 hdd 14.61089 osd.2 up 1.00000 1.00000 3 hdd 14.61089 osd.3 up 1.00000 1.00000 This shows that the tree is essentially unchanged, it just "gained a level". In `ceph status` I now get: pgs: 1167541260/1595506041 objects misplaced (73.177%) If I remove the `datacenter` level again, then the misplacement disappears. On a minimal testing cluster, this misplacement issue did not appear. Why does Ceph think that these objects are misplaced when I add the datacenter level? Is there a more correct way to do this? Thanks!