Ceph – another mystery error

Cannot place on myhost: Unknown hosts

Ran into this when attempting to use ceph orch to manage mgr’s.

It’s actually quite simple and has nothing (directly) to do with /etc/hosts or DNS. Only with the list of hosts that ceph knows internally.

And the problem — yet again — is that Ceph doesn’t manage multiple hostnames!!!

The hostname was registered as “myhost.mousetech.com”, but I had requested like this:

ceph orch apply mgr --placement="ceph01 myhost"

“ceph01” was OK, since that’s how Ceph had been set up. But when I added “myhost”, I did so with the fully-qualifed domain name. The bloody names must match what Ceph has on file exactly. Grrr!

So the proper command was:

ceph orch apply mgr --placement="ceph01 myhost.mousetech.com"

Author: Tim

Evil Genius specializing in OS's, special hardware and other digital esoterica with a bent for Java.