Hi, For reference, I ran in to the same thing recently, this is because the command cepg odd reweight only changes the weight of the osd. Ceph osd crush reweight also changes the weight of the bucket(s) the osd is in (host, rack, room etc)[1]. I expect the reason is for the scenario that the disk would be replaced with another disk of the same size, it would be easier to rebalance back with the new disk. I don't see that as a very common occurrence in my use cases, but maybe that is the more common use case still for others. Best! [1] https://ceph.io/en/news/blog/2014/difference-between-ceph-osd-reweight-and-ceph-osd-crush-reweight/ ________________________________ From: "Nico Schottelius 'nico.schottelius at ungleich.ch'" <7ba335c6-fb20-4041-8c18-1b00efb7824c+nico.schottelius=ungleich.ch@xxxxxxxxxxx> Sent: Sunday, May 29, 2022 09:11 To: 7ba335c6-fb20-4041-8c18-1b00efb7824c@xxxxxxxxxxx Subject: Re: Rebalance after draining - why? Thanks a lot everyone for your answers! That is very helpful. In the future, if anyone is looking at this thread: It's ceph osd crush reweight osd.XX 0 instead of ceph osd reweight osd.XX 0 for draining an OSD out of a cluster. Best regards and many greetings from the Swiss mountains, Nico Nico Schottelius <nico.schottelius@xxxxxxxxxxx> writes: > Good evening dear fellow Ceph'ers, > > when removing OSDs from a cluster, we sometimes use > > ceph osd reweight osd.XX 0 > > and wait until the OSD's content has been redistributed. However, when > then finally stopping and removing it, Ceph is again rebalancing. > > I assume this is due to a position that is removed in the CRUSH map and > thus the logical placement is "wrong". (Am I wrong about that?) > > I wonder, is there a way to tell ceph properly that a particular OSD is > planned to leave the cluster and to remove the data to the "correct new > position" instead of doing the rebalance dance twice? > > Best regards, > > Nico -- Sustainable and modern Infrastructures by ungleich.ch _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx ----- This email was sent to 7ba335c6-fb20-4041-8c18-1b00efb7824c@xxxxxxxxxxx (ceph-user) from nico.schottelius@xxxxxxxxxxx and has been forwarded by AnonAddy. To deactivate this alias copy and paste the url below into your web browser. https://app.anonaddy.com/deactivate/7ba335c6-fb20-4041-8c18-1b00efb7824c?signature=bac13a3b3016883e2bb0736418346fb1fed5f22615ec0c87dfe8d8f903e4eb3d _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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