Comment 0 for bug 1836092

Sandor Zeestraten (szeestraten) wrote :

The default crush algorithm used by the charms is `straw`, while `straw2` was the new default in the Hammer release (http://docs.ceph.com/docs/mimic/rados/operations/crush-map/#hammer-crush-v4).

Deployments with `straw` will need to migrate to `straw2` in order to utilise newer features in Luminous such as the mgr balance plugin (https://ceph-users.ceph.narkive.com/fFMZOiMg/error-creating-compat-weight-set-with-mgr-balancer-plugin).

> Migration impact:
> Changing a bucket type from straw to straw2 will result in a reasonably small amount of data movement, depending on how much the bucket item weights vary from each other. When the weights are all the same no data will move, and when item weights vary significantly there will be more movement.

Offending line: https://github.com/openstack/charm-ceph-mon/blob/master/lib/ceph/crush_utils.py#L27