On 07/06/2014 11:29 PM, Erik Logtenberg wrote: > Hi, > > I have some osd's on hdd's and some on ssd's, just like the example in > these docs: > > http://ceph.com/docs/firefly/rados/operations/crush-map/ > > Now I'd like to place an erasure encoded pool on the hdd's and a > replicated (cache) pool on the ssd's. In order to do that, I have to > split the crush maps into two roots, according to the docs. > Correct, you'll have a root 'ssd' and 'default' or 'hdd'. > The way the docs describe it, I have to create two roots, and then > separate "server"-nodes for ssd's and hdd's, then the osd's under the > right server node. > My hdd's and ssd's are mixed within hosts though: I have four physical > hosts each with a couple of hdd's and an ssd. So there is not a > hdd-server and a ssd-server, like in the docs. Or do I have to create > two server-nodes per host? It appears to me that not all rules will > still work the same way in that case. You have to create these hosts indeed. A 'Host' in a crushmap is nothing more then a bucket to crush. In the end the CRUSH result is a OSD device and through the OSDMap the cluster knows on which IP/port that specific OSD lives. It's just for us that we make the crushmap easy by naming the 'Host' the same in the crushmap as it is in real life. So you create these two hosts in the crushmap and place the correct OSDs under these hosts. You have to modify all your rules as well. I recommend you test the crushmap prior before injecting it into the cluster: $ crushtool -i mymap --test --rule X --num-rep 3 --show-statistics That will give you a quick overview of how the map works. Don't forget this part however: http://eu.ceph.com/docs/firefly/rados/operations/crush-map/#crush-location Otherwise the auto updating of the crushmap on OSD boot will modify your crushmap again. Wido > > Regards, > > Erik. > _______________________________________________ > ceph-users mailing list > ceph-users at lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Wido den Hollander 42on B.V. Ceph trainer and consultant Phone: +31 (0)20 700 9902 Skype: contact42on
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