Migrating from a single machine setup to another single machine setup

[Wouter Samaey]

We currently have a single machine Proxmox setup with 1 VM inside.
The hardware is getting old and needs to be replaced.

Typically, we would:
1) Prepare the new machine
2) Stop the VM on the old machine
3) Backup the VM
4) Transfer the VM
5) Start the VM on the new machine
6) Change all the IPs in all the DNS records (not all under my control)
7) Send out emails so everyone can change their DNS records
8) Change the original VM so it forwards web traffic to the new IP in case people do not change the DNS fast enough. These websites will be slower, but at least they will work.

I guess this is a pretty "normal" migration.

Now I was wondering if there isn't an easier route by connecting the 2 Proxmox servers together, migrate the VM and have Proxmox do the IP routing automatically? We currently do NOT have shared storage which is a requirement I guess, just the 2 machines.

We do have an external disk that both machines can access through SMB.

Having to deal with all these IP/DNS changes is making me nervous, expecially since I know a number of people will need hand-holding to make the DNS changes.

Are there any options here? Any ideas that can improve our process are very welcome.

PS: I should note that the Proxmox versions differ on the old and new servers.

Thanks!

 

[aaron]

I am a bit confused, which IP addresses are we talking about? The one of the VM or the one of the Proxmox host?
If you keep the old and new Proxmox hosts running at the same time they of course need to have two different IP addresses. If you transfer the VM to the new server and it is in the same network you should not have to change any IP of the VM.

 

[Wouter Samaey]

I'm sorry, the VM has an "additional IP" that we got from the datacenter. This IP cannot be kept / moved to the new machine because the IPs are linked to the rack. The new server will be in a different rack.

In other words, the publicly facing IP that the VM uses will change.
The hypervisors each have their own IPs, but that's okay.

 

[velocity08]

I'm sorry, the VM has an "additional IP" that we got from the datacenter. This IP cannot be kept / moved to the new machine because the IPs are linked to the rack. The new server will be in a different rack.

In other words, the publicly facing IP that the VM uses will change.
The hypervisors each have their own IPs, but that's okay.

Hi Wouter

Hope you don’t mind if i chime in with some questions.

• Are you keeping the physical host in the same DC?
• Are the VM’s on the host allocated an IPv4 public address?
• I’ve never seen a public address allocated to a rack they are normally allocated to a DataCentre location and are portable between hosts in different racks.
• Why cant the DC provide a cross connect to the other host even if its in another rack?
• Do you run your own DNS servers or use the DC’s public facing DNS servers?

I’m happy to provide some advise If you like but need to know more info on the setup.

To be straight up all that’s needed is another Nic or a spare Nic in each host that has its own internal IP address on a seperate subnet i.e.
host 1 - 10 0.2.2
host 2 - 10.0.2.3

Have the DC crossover connect the hosts between racks they should all be interconnected they can either use a cross over cable if the hosts are close or via the top of rack switch.

Both hosts should be able to talk on the same internal subnet range and with this you should be able to do an offline migration between the 2 hosts.

The above is just 1 example, other solutions are available just need more info.

Let me know if you would like more info.

“”Cheers
G

 

[aaron]

Okay, as far as I understand the situation, the problem is not the migration but that the VM has an additional IP assigned (let's call it public IP) which is most likely used to access it from the internet, hence many DNS records pointing to this IP address.
For some reason the datacenter cannot provide the same IP in another rack...

Now I was wondering if there isn't an easier route by connecting the 2 Proxmox servers together, migrate the VM and have Proxmox do the IP routing automatically?

Is this what you ask: Keep the old Proxmox host running and route the old public IP from the old Proxmox host to the VM running on the new Proxmox host?

Proxmox does not offer anything like that. VMs use the network interfaces of the host they are running on.

My advice if the datacenter really cannot let you use the same old public IP in the new rack is to change the way you manage your DNS is this: create one DNS A record that is pointing to your public IP address and all other records who need to point to that IP should be CNAME records.

This way you reduce the points where you have to change the DNS records. Domains themselves (domain.tld) cannot be CNAME records as far as I remember. So those you still need to change.