Changing SUBNET on running cluster

[Justy]

(I have changed from Untangle to Ubiquity - and as part of that, I want to be more VLAN-aware, etc. but I haven't got that far yet.)
(PVE newbie but I have been running 1+ year successfully - but without the need for this deeper knowledge)

My problem is essentially based in the change of DHCP address scope
- old DHCP range: 10.100.100.100.222 ---- 10.100.100.225
- new DHCP range: 10.10.10.10 ---- 10.10.10.15
I cannot get rid the old 10.100.100.### IPs --> i.e., change to 10.10.10.###

I have changed the proxmox IP so I have access to the proxmox GUI and I can observe that Quorum is not working!


It tries the old hardwired 10.100.100.### range - that's the core problem: I cannot change it - or find the right method to do it :-(

I have tried via GUI - no chance; all fields are greyed out and I can only get the Join text for 10.100.100.### - i.e., I cannot change anything (like to 10.10.10.###)

Then I looked through proxmox, Google, etc. - and found great pages showing how to change corosync.cfg (two files, etc. - with all kind of awareness) - BUT...
I cannot change the files in PVE - and even not the file directory permissions (via root chmod...)

I tried (just to try) to edit the /etc/hosts file to include the new host IPS - but after a reboot, the files is back to 10.100.100.### (likely by PVE sanity!)



So there are some basic security/terms that I am not aware of - and cannot find resources on how to do it - besides this great knowledgeable forum
I am deeply worried that my Home Assistant (that is running on one of the hosts with no Quorum) will reboot - and not restart due to this trouble



And status corosync - if that info can contribute?



TIA!!!

 

[cheiss]

Hi,

Proxmox VE does not use DHCP by default for the host, nor is it really supported. (Since, as you discovered, changing the IP address(es) of a node is not trivial).

What does your /etc/network/interfaces and /etc/pve/corosync.conf look like? Did you properly adjust the IP addresses there?

I'd recommend also reading the Separate Cluster Network article, which should provide all the steps you need to take.

 

[Justy]

Thanks for your quick reply!

You are quite right; I should have used the term SUBNET (AFAIK) but it is derived from the DHCP Server serves another subnet IP range. So I took the opportunity to "clean up" (in preparation for later work) using the 10.10.10 subnet…
And… it is indeed the separation of networks that I am aiming for (later) together with Ceph but that is on the learning curve ahead...

For now, I just want to get my proxmox cluster back up and running with Quorum in the new subnet 10.10.10 (instead of 10.100.100) IP address space.

I am indeed using fixed/reserved DHCP IP address on the DHCP Service so I have adjusted interfaces to accommodate this:



BUT as I tried to pinpoint/describe in my first post: The KEY problem is that I cannot edit/change the corosync.conf file (as root.)



THAT is the problem; the corosync.conf is ReadOnly as listed by the file directory (incl. the directory permissions so I cannot even make a copy of it before editing (as usually recommended)!)

 

[Justy]

Updated the Thread name from DHCP to subnet as that is more appropriate - AFAIK...