Hi Carsten,
On 11/30/2015 10:08 AM, Carsten Schmitt wrote:
Hi all,
I'm running ceph version 0.94.5 and I need to downsize my servers
because of insufficient RAM.
So I want to remove OSDs from the cluster and according to the manual
it's a pretty straightforward process:
I'm beginning with "ceph osd out {osd-num}" and the cluster starts
rebalancing immediately as expected. After the process is finished,
the rest should be quick:
Stop the daemon "/etc/init.d/ceph stop osd.{osd-num}" and remove the
OSD from the crush map: "ceph osd crush remove {name}"
But after entering the last command, the cluster starts rebalancing
again.
And that I don't understand: Shouldn't be one rebalancing process
enough or am I missing something?
Removing the OSD changes the weight for the host, thus a second
rebalance is necessary.
The best practice to remove an OSD involves changing the crush weight to
0.0 as first step.
- ceph osd crush reweight osd.X 0.0
... wait for rebalance to finish....
- ceph osd out X
... stop OSD daemon ....
- ceph osd crush remove osd.X
- ceph auth del osd.X
- ceph osd rm X
Regards,
Burkhard
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