On Wed, Mar 9, 2016 at 1:57 PM, Александр Шишенко <gamepad64@xxxxxxxxx> wrote: > Well, my aim is to make replicas request chunks of data from each > other during the recovery process, but not from primary. So, let's > consider the three-osd cluster with a PG residing on it: > node1(primary), node2(replica), node3(replica), 3in/3up active+clean > > Now, let's shutdown node3. > node1(primary), node2(replica), node3(replica), 3in/2up > active+undersized+degraded > > After node3 comes back online, the recovery is started and node1 sends > chunks of data node3. Is there a way to make node2 send these chunks > instead of node1 without making node2 a primary? Oh, I see. I think you're missing that there are many PGs on each OSD, and you will generally be recovering more than one PG at a time. So rather than doing the (extreme and difficult) bookkeeping to allow recovery directly via replicas, we count on having PGs whose primary is different to distribute that work. :) -Greg > > 2016-03-10 0:42 GMT+03:00 Gregory Farnum <gfarnum@xxxxxxxxxx>: >> On Wed, Mar 9, 2016 at 2:21 AM, Александр Шишенко <gamepad64@xxxxxxxxx> wrote: >>> Hello, >>> >>> I have a development cluster of three OSD's. My aim is to make a >>> secondary replica recover from another secondary replica (not >>> primary). Is it possible to do so with minor changes to ceph-osd >>> source code? Are ceph algorithms compatible with these changes? >> >> I'm not sure what you mean by these statements. While we have a >> primary and replicas in Ceph, that status is ephemeral — if the >> primary disappears, one of the replicas will become primary. Recovery >> is orchestrated and largely involves whichever node is currently the >> primary, but if the primary is unsuitable for that it maps one of the >> secondary replicas to be primary for the duration of the recovery... >> -Greg > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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