OK, I remember now, if I don't remove the OSD from the CRUSH, ceph-disk will get a new OSD ID and the old one will hang around as a zombie. This will change the host/rack/etc weights causing cluster wide rebalance.
On Tue, Apr 14, 2015 at 9:31 AM, Robert LeBlanc <robert@xxxxxxxxxxxxx> wrote:
Hmmm....I've been deleting the OSD (ceph osd rm X; ceph osd crush rm osd.X) along with removing the auth key. This has caused data movement, but reading your reply and thinking about it made me think it should be done differently. I should just remove the auth key and leave the OSD in the CRUSH map. That should work, I'll test it on my cluster.I'd still like to know the difference between norecover and nobackfill if anyone knows.On Mon, Apr 13, 2015 at 7:40 PM, Francois Lafont <flafdivers@xxxxxxx> wrote:Hi,
Robert LeBlanc wrote:
> What I'm trying to achieve is minimal data movement when I have to service
> a node to replace a failed drive. [...]
I will perhaps say something stupid but it seems to me that it's the
goal of the "noout" flag, isn't it?
1. ceph osd set noout
2. an old OSD disk failed, no rebalancing of data because noout is set, the cluster is just degraded.
3. You remove of the cluster the OSD daemon which used the old disk.
4. You power off the host and replace the old disk by a new disk and you restart the host.
5. You create a new OSD on the new disk.
With these steps, there will be no movement of data. Only during the step 5
where the data will be recreated in the new disk (but it's normal and desired).
Sorry in advance if there is something I'm missing in your problem.
Regards.
--
François Lafont
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