On 5/14/14 06:36 , Dinu Vlad wrote:
Hi Dinu,
On Wed, 14 May 2014, Dinu Vlad wrote:
I'm running a ceph cluster with 3 mon and 4 osd nodes (32 disks total) and I've been
looking at the possibility to "migrate" the data to 2 new nodes. The operation
should happen by relocating the disks - I'm not getting any new hard-drives. The cluster
is used as a backend for an openstack cloud, so downtime should be as short as possible -
preferably not more than 24 h during the week-end.
I'd like a second opinion on the process - since I do not have the resources to
test the move scenario. I'm running emperor (0.72.1) at the moment. All pools
in the cluster have size 2. Each existing OSD nodes have each an SSD for
journals; /dev/disk/by-id paths were used.
Here's what I think would work:
1 - stop ceph on the existing OSD nodes (all of them) and shutdown the node 1 &
2;
2 - take drives 1-16/ssds 1-2 out and put them in the new node #1; start it up
with ceph's upstart script set on manual and check/correct journal paths
3 - edit the CRUSH map on the monitors to reflect the new situation
4 - start ceph on the new node #1 and old nodes 3 & 4; wait for the rebuild to
happen
5 - repeat steps 1-4 for the rest of the nodes/drives;
If you used ceph-deploy and/or ceph-disk to set up these OSDs (that is, if
they are stored on labeled GPT partitions such that upstart is
automagically starting up the ceph-osd daemons for you without you putting
anythign in /etc/fstab to manually mount the volumes) then all of this
should be plug and play for you--including step #3. By default, the
startup process will 'fix' the CRUSH hierarchy position based on the
hostname and (if present) other positional data configured for 'crush
location' in ceph.conf. The only real requirement is that both the osd
data and journal volumes get moved so that the daemon has everything it
needs to start up.
sage
If you used disk encryption (ceph-deploy --dmcrypt), you'll also need to
copy the keys from /etc/ceph/dmcrypt-keys/.
--
*Craig Lewis*
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