Ceph

On a smaller Ceph cluster we had a disk fail.

That probably happened in the middle of the night and nobody noticed.

So the disk had the 'out' state.

During the day, the there was no data-migration active at the time.

Now when you read the documentation:

http://ceph.com/docs/master/rados/operations/add-or-rm-osds/

It clearly says in this order:
- ceph osd out

- Observe the Data Migration

- ceph osd crush remove {name}

So you would get the impression if that happens that there would be no data migration when you remove from the crushmap.

This seems to be not the case.

After you remove a disk from the crush map, there will be a data migration.

Which makes sense if you think about what 'remove from the crushmap' means.

As you can imagine, it's not so much fun on a small cluster to have an unplanned data migration.

Could you please change the documentation to fit the what really happends.

Thank you.