Try "ceph osd set noout" beforehand and then "ceph osd unset noout". That will prevent any OSDs from getting removed from the mapping, so no data will be rebalanced. I don't think there's a way to prevent OSDs from getting zapped on an individual basis, though. This is described briefly in the docs at http://ceph.com/docs/master/rados/operations/troubleshooting-osd/?highlight=noout, though it could probably be a bit more clear. -Greg On Thursday, January 31, 2013 at 11:40 PM, Alexis GÜNST HORN wrote: > Hello to all, > > Here is my setup : > > - 2 racks > - osd1 .. osd6 in rack1 > - osd7 .. osd12 in rack2 > - replica = 2 > - CRUSH map set to put replicas accross racks > > My question : > Let's imagine that one day, I need to unplug one of the racks (let's > say, rack1). No problem because an other copy of my objects will be in > the other rack. But, if i do it, Ceph will start to rebalance data > accross OSDs. > > So, is there a way to put nodes in "Maintenance mode", in order to put > Ceph in "degraded" mode, but avoiding any remaping. > > The idea is to have a command like : > > $ ceph osd set maintenance=on osd.1 > $ ceph osd set maintenance=on osd.2 > $ ceph osd set maintenance=on osd.3 > $ ceph osd set maintenance=on osd.4 > $ ceph osd set maintenance=on osd.5 > $ ceph osd set maintenance=on osd.6 > > So Ceph knows that 6 osds are down, goes into degraded mode, but > without remapping data. > Then, once maintenance finished, i'll only have to do the opposite : > > $ ceph osd set maintenance=off osd.1 > $ ceph osd set maintenance=off osd.2 > $ ceph osd set maintenance=off osd.3 > $ ceph osd set maintenance=off osd.4 > $ ceph osd set maintenance=off osd.5 > $ ceph osd set maintenance=off osd.6 > > What do you think ? > I know that there is a way in Ceph doc to do so with reweight, but > it's a little bit complex... > > What do you think ? > Thanks, > > Alexis > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx (mailto:majordomo@xxxxxxxxxxxxxxx) > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
