On Mon, Mar 4, 2013 at 12:19 AM, Olivier Bonvalet <ceph.list@xxxxxxxxx> wrote: > Hello, > > I have a running cluster, which use the (previous) default CRUSH rule, > with : > step take default > step choose firstn 0 type osd > step emit > > Since I have multiple OSD in the same host, I need to change that to > have better redondancy. > My crush map use types datacenter → room → network → rack → host → osd. > > For now I would like to replicate per "network", I suppose I can simply > replace "step choose firstn 0 type osd" per "step choose firstn 0 type > network" ; but is it safe to do that on a running cluster ? Not quite — you'll want to do "step chooseleaf firstn 0 type network". See http://ceph.com/docs/master/rados/operations/crush-map for details on this stuff. Yes, it is safe to do on a running cluster. > And I suppose it will throw a lot of data move, is it possible to do > that «slowly», to avoid production slowdown ? Yeah, it's likely to move the entire contents. If you're on Argonaut you're kind of stuck; if Bobtail then you have some control through the "osd_max_backfills" option (defaults to 10) that specifies how many moves each OSD will let itself be involved in at once. You should practice on a non-production cluster first to make sure you don't run into issues with pgtemp or OSDMap generation, though. -Greg _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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