I would still always recommend having at least having n+1 failure domain in any production cluster where n is your replica size.
On Tue, Jul 18, 2017, 11:20 PM David Turner <[email protected]> wrote: > You do not need to empty the host before moving it in the crush map. It > will just cause data movement because you are removing an item under root > and changing the crush weight of the rack. There is no way I am aware of > to really ease into this data movement other than to stare it head on and > utilize osd_max_backfills to control disk io in your cluster. > > Are you changing you're failure domain to rack from host after this is > done? Changing that in the crush map will cause everything to peer at once > and then instigate a lot of data movement. You can do both moving the hosts > into their racks and change the failure domain in the same update to only > move data once. You would do that by downloading the crush map, modifying > it, and then uploading it back into the cluster. It would be smart to test > this on a test cluster. You could even do it on a 3 node cluster by > changing each node to its own rack and setting the failure domain to rack. > > On Tue, Jul 18, 2017, 7:06 PM Mike Cave <[email protected]> wrote: > >> Greetings, >> >> >> >> I’m trying to figure out the best way to move our hosts from the >> root=default bucket into their rack buckets. >> >> >> >> Our crush map has the notion of three racks which will hold all of our >> osd nodes. >> >> >> >> As we have added new nodes, we have assigned them to their correct rack >> location in the map. However, when the cluster was first conceived, the >> majority of the nodes were left in the default bucket. >> >> >> >> Now I would like to move them into their correct rack buckets. >> >> >> >> I have a feeling I know the answer to this question, but I thought I’d >> ask and hopefully be pleasantly surprised. >> >> >> >> Can I move a host from the root bucket into the correct rack without >> draining it and then refilling it or do I need to reweight the host to 0, >> move the host to the correct bucket, and then reweight it back to it’s >> correct value? >> >> >> >> Any insights here will be appreciated. >> >> >> >> Thank you for your time, >> >> Mike Cave >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >
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