When we know we need to off a node, we weight it down over time. Depending on your cluster, you may need to do this over days or hours.
In theory, you could do the same when putting OSDs in, by setting noin, and then setting weight to something very low, and going up over time. I haven¹t tried this though. -- Warren Wang Comcast Cloud (OpenStack) On 8/31/15, 2:57 AM, "ceph-users on behalf of Udo Lembke" <ceph-users-boun...@lists.ceph.com on behalf of ulem...@polarzone.de> wrote: >Hi Christian, >for my setup "b" takes too long - too much data movement and stress to >all nodes. >I have simply (with replica 3) "set noout", reinstall one node (with new >filesystem on the OSDs, but leave them in the >crushmap) and start all OSDs (at friday night) - takes app. less than one >day for rebuild (11*4TB 1*8TB). >Do also stress the other nodes, but less than with weigting to zero. > >Udo > >On 31.08.2015 06:07, Christian Balzer wrote: >> >> Hello, >> >> I'm about to add another storage node to small firefly cluster here and >> refurbish 2 existing nodes (more RAM, different OSD disks). >> >> Insert rant about not going to start using ceph-deploy as I would have >>to >> set the cluster to no-in since "prepare" also activates things due to >>the >> udev magic... >> >> This cluster is quite at the limits of its IOPS capacity (the HW was >> requested ages ago, but the mills here grind slowly and not particular >> fine either), so the plan is to: >> >> a) phase in the new node (lets call it C), one OSD at a time (in the >>dead >> of night) >> b) empty out old node A (weight 0), one OSD at a time. When >> done, refurbish and bring it back in, like above. >> c) repeat with 2nd old node B. >> >> Looking at this it's obvious where the big optimization in this >>procedure >> would be, having the ability to "freeze" the OSDs on node B. >> That is making them ineligible for any new PGs while preserving their >> current status. >> So that data moves from A to C (which is significantly faster than A or >>B) >> and then back to A when it is refurbished, avoiding any heavy lifting >>by B. >> >> Does that sound like something other people might find useful as well >>and >> is it feasible w/o upsetting the CRUSH applecart? >> >> Christian >> > >_______________________________________________ >ceph-users mailing list >ceph-users@lists.ceph.com >http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
