Just to piggyback on this, the below are the correct answers. However, how I do it, which is admittedly not the best way, but it is the easy way. I set the norecover, nobackfill flags I run my osd creation script against the first disk on the new host to make sure that everything is working correctly, and also so that I can then manually move my new host bucket where I need it in the crush map with Then I proceed with my script for the rest of the OSDs on that host and know that they will fall into the correct crush location. And then of course I unset the norecover, nobackfill flags so that data starts moving. I only mention this because it ensures that you don't fat finger the hostname on manual bucket creation, or the hostname syntax doesn't match as expected, and it allows you to course correct after a single OSD added, rather than all N OSDs. Hope thats also helpful. Reed > On Dec 2, 2020, at 4:38 PM, Dan van der Ster &lt;dan(a)vanderster.com&gt; wrote: > > Hi Francois! > > If I've understood your question, I think you have two options. > > 1. You should be able to create an empty host then move it into a room > before creating any osd: > > ceph osd crush add-bucket <hostname> host > ceph osd crush mv <hostname> room=<the room> > > 2. Add a custom crush location to ceph.conf on the new server so that > its osds are placed in the correct room/rack/host when they are first > created, e.g. > > [osd] > crush location = room=0513-S-0034 rack=SJ04 host=cephdata20b-b7e4a773b6 > > Does that help? > > Cheers, Dan > > > > On Wed, Dec 2, 2020 at 11:29 PM Francois Legrand > &lt;fleg(a)lpnhe.in2p3.fr&gt; wrote: >> >> Hello, >> >> I have a ceph nautilus cluster. The crushmap is organized with 2 rooms, >> servers in these rooms and osd in these servers, I have a crush rule to >> replicate data over the servers in different rooms. >> >> Now, I want to add a new server in one of the rooms. My point is that I >> would like to specify the room of this new server BEFORE creating osd in >> this server (so the data added to the osd will be directly at the right >> location). My problem is that it seems that servers appears in the >> crushmap only when they have osds... and when you create a first osd, >> the server is inserted in the crushmap under the default bucket (so not >> in a room and then the first data stored in this osd will not be at the >> correct location). I could move it after (if I do it rapidly, there will >> be no that much data to move after), but I was wondering if there is a >> way to either define the position of a server in the crushmap hierarchy >> before creating osd or eventually to specify the room when creating the >> first osd ? >> >> F. >> _______________________________________________ >> ceph-users mailing list -- ceph-users(a)ceph.io >> To unsubscribe send an email to ceph-users-leave(a)ceph.io > _______________________________________________ > ceph-users mailing list -- ceph-users(a)ceph.io > To unsubscribe send an email to ceph-users-leave(a)ceph.io

在 2020年12月4日，00:00，Francois Legrand &lt;fleg(a)lpnhe.in2p3.fr&gt; 写道： Thank for your advices. it was exactly what I needed. Indeed, I did a : ceph osd crush add-bucket <hostname> host ceph osd crush move <hostname> room=<the room> But also set the norecover, nobackfill and norebalance flags :-) It worked perfectly as expected. F. _______________________________________________ ceph-users mailing list -- ceph-users(a)ceph.io To unsubscribe send an email to ceph-users-leave(a)ceph.io

You can also just use a single command: ceph osd crush add-bucket <hostname> host room=<the room>