I'm glad it worked for you. We used the 'swap-bucket' command when we
needed to replace an OSD node without waiting for the draining of the
old one to finish and then wait for the backfilling of the new one. I
created a temporary bucket where I moved the old host (ceph osd crush
move <host> <temp-bucket>), the data was still available, and then
issued 'swap-bucket' which started to drain the old host directly to
the new host. This saved a lot of time and network traffic.
Zitat von "Rice, Christian" <crice@xxxxxxxxxxx>:
Hi all, so I used the rename-bucket option this morning for OSD node
renames, and it was a success. Works great even on Luminous.
I looked at the swap-bucket command and I felt it was leaning toward
real data migration from old OSDs to new OSDs and I was a bit timid
because there wasn’t a second host, just a name change. So when I
looked at rename-bucket, it just seemed too simple not to try first.
And I did, and it was. I renamed two host buckets (they housed
discrete storage classes, so no dangerous loss of data redundancy),
and even some rack buckets.
sudo ceph osd crush rename-bucket <oldname> <newname>
and no data moved. I first thought I’d wait til the hosts were
shutdown, but after I stopped the OSDs on the nodes, it seemed safe
enough, and it was.
In my particular case, I was moving migrating nodes to a new
datacenter, just new names and IPs. I also moved a mon/mgr/rgw;
and I merely had to delete the mon first, then reprovision it later.
The rgw and mgr worked fine. I pre-edited ceph.conf to add the new
networks, remove the old mon name, add the new mon name, so on
startup it worked.
I’m not a ceph admin but I play one on the tele.
From: Eugen Block <eblock@xxxxxx>
Date: Wednesday, February 15, 2023 at 12:44 AM
To: ceph-users@xxxxxxx <ceph-users@xxxxxxx>
Subject: [EXTERNAL] Re: Renaming a ceph node
Hi,
I haven't done this in a production cluster yet, only in small test
clusters without data. But there's a rename-bucket command:
ceph osd crush rename-bucket <srcname> <dstname>
rename bucket <srcname> to <dstname>
It should do exactly that, just rename the bucket within the crushmap
without changing the ID. That command also exists in Luminous, I
believe. To have an impression of the impact I'd recommend to test in
a test cluster first.
Regards,
Eugen
Zitat von Manuel Lausch <manuel.lausch@xxxxxxxx>:
Hi,
yes you can rename a node without massive rebalancing.
The following I tested with pacific. But I think this should work with
older versions as well.
You need to rename the node in the crushmap between shutting down the
node with the old name and starting it with the new name.
You only must keep the ID from the node in the crushmap!
Regards
Manuel
On Mon, 13 Feb 2023 22:22:35 +0000
"Rice, Christian" <crice@xxxxxxxxxxx> wrote:
Can anyone please point me at a doc that explains the most
efficient procedure to rename a ceph node WITHOUT causing a massive
misplaced objects churn?
When my node came up with a new name, it properly joined the
cluster and owned the OSDs, but the original node with no devices
remained. I expect this affected the crush map such that a large
qty of objects got reshuffled. I want no object movement, if
possible.
BTW this old cluster is on luminous. ☹
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