On Fri, Oct 7, 2016 at 1:21 PM, Jeff Applewhite <japplewh@xxxxxxxxxx> wrote: > Hi All > > I have a few questions pertaining to management of MONs and OSDs. This is in > a Ceph 2.x context only. You mean Jewel? ;) > ----------------------------------------------- > 1) Can MONs be placed in something resembling maintenance mode (for firmware > updates, patch reboots, etc.). If so how? If not how addressed? > > 2) Can OSDs be placed in something resembling maintenance mode (for firmware > updates, patch reboots, etc.). If so how? If not how addressed? In both of these cases, you just turn it off. Preferably politely (ie, software shutdown) so that the node can report to the cluster it won't be available. But it's the same as any other failure case from Ceph's perspective: the node is unavailable for service. See http://docs.ceph.com/docs/master/install/upgrading-ceph, which is a little old now but illustrates the basic ideas. > > 3) Can MONs be "replaced/migrated" efficiently in a hardware upgrade > scenario? If so how? If not how addressed? Monitors can be moved if they can keep the same IP; otherwise you need to go through some shenanigans: http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/#changing-a-monitor-s-ip-address Or you can add the new location and remove the old location (hopefully in that order, to maintain your durability, but you could do it the other way around if reeeeally necessary): http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ > > 4) Can OSDs be "replaced/migrated" efficiently in a hardware upgrade > scenario? If so how? If not how addressed? You can move an OSD around as long as you either flush its journal or the journal device is colocated or moved with it. But by default it will then update to a new CRUSH location and all the data will reshuffle anyway. You can also mark an OSD out while keeping it up and the cluster will then backfill all its data the correct new locations without ever reducing redundancy. (http://docs.ceph.com/docs/master/rados/operations/add-or-rm-osds/) This gets into the typical concerns about changing CRUSH weights and migrating data unnecessarily if you aren't removing the whole host/rack/whatever, but it sounds like are only interested in wholesale replacement. It's also possible to clone the drive or whatever and just stick it in place, in which case Ceph doesn't really notice (maybe modulo some of the install or admin stuff on the local node, but the cluster doesn't care). I've included some links directly relevant throughout but there's plenty of other info in the docs and you probably want to spend some time reading them carefully if you're planning to build a management tool. :) -Greg _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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