For this guide: https://docs.redhat.com/en/documentation/red_hat_openstack_platform/17.1/html/installing_and_managing_red_hat_openstack_platform_with_director/assembly_replacing-controller-nodes#proc_removing-a-ceph-monitor-daemon_replacing-controller-nodes

Section 11.2 is specific to removing Ceph Mon for controller replacement, There should be guidance/warning about handling Mon IP changes.

The Ceph Mon IPs are hard-coded into running VM instances[1] and do not get dynamically updated.

In a situation where all controllers are replaced with new IPs an outage would occur for all VMs in the environment. Each VM would need to be shelved/unshelved to resolve the Mon IP change.

We should guide users to re-use Mon IPs here and clarify the impact of this IP change.

[1] example showing hard coded Mon IPs
[root@compute18-node2 ~]# virsh domblklist 1
Target Source
----------------------------------------------------------------
vda vms/7bd75b76-cec1-4d4e-8f4c-97a5b84e09f8_disk
sda vms/7bd75b76-cec1-4d4e-8f4c-97a5b84e09f8_disk.config

[root@compute18-node2 ~]# virsh dumpxml 1|grep -A4 rbd
<source protocol='rbd' name='vms/7bd75b76-cec1-4d4e-8f4c-97a5b84e09f8_disk' index='2'>
<host name='172.16.21.10' port='6789'/>
<host name='172.16.21.4' port='6789'/>
<host name='172.16.21.26' port='6789'/>
</source>
–
<source protocol='rbd' name='vms/7bd75b76-cec1-4d4e-8f4c-97a5b84e09f8_disk.config' index='1'>
<host name='172.16.21.10' port='6789'/>
<host name='172.16.21.4' port='6789'/>
<host name='172.16.21.26' port='6789'/>
</source>