Can we change a Master server to another server?

We have a Master and a Slave Cloudmin server and would like to move the Master Role to another server and change the actual master server hardware.
Can it be done?

If we have the master server down, how can we manage the vm’s running on slave servers?

Paulo Cardoso

So if you want to move your Cloudmin master settings to another system, here’s what I would recommend :

  1. Install Cloudmin on the new system.

  2. Transfer the /etc/webmin/servers and /etc/webmin/server-manager directories from the old system to the new.

  3. Shut down the old system…

All VMs hosted on other systems will continue to run. However, if you have VMs hosted on the old master, they will need to be manually transferred across…

What if I install the server as slave, migrate the machines from master to that slave and them move that folders?
Will it work?

Could you explain what you mean by a slave exactly? Cloudmin doesn’t really have anything that is calls a slave …


I call slave to the additional servers for Cloudmin.
We have a 10 server license and installed it on one server (master). Then we installed a new server and added it to the Master configuration.
After that we can migrate VM’s from “Master” to “Slave” server.
We have some machines on the “Master” and others on “Slave”.
Now we would like to change the “Master Role” to the “Slave” server and shut down the actual “Master” server.
After that we would like to have only one server with all the VM’s and acting as “Master”.

Can it be done live?

Ok, I see what you mean now … Cloudmin uses the term “host” to refer to a system that can host virtual systems like Xen instances. The “master” can be a host, as can other physical systems.

So in your case, here’s what I would recommend if you want to move the master role :

  1. Install Cloudmin on the new master system.

  2. Copy the /etc/webmin/servers , /etc/webmin/server-manager and /var/webmin/server-manager directories from the old master to the new.

  3. Shut down the old master

All running virtual systems should continue to operate just fine.

I’ll also mention that we do have plans to provide for Cloudmin redundancy, and a notion of master and replicas. It’ll be a little while before that capability shows up, but reliability, redundancy and scalability are useful features of cloud computing services, so the tools that help build cloud computing services ought to also have those features.

Jamie and I hashed out how this might work on our drive up to Davis recently, and I think we have a pretty good plan for how to implement it.


Can you please tell me when this feature will be implemented? I’m looking for a solution where the CloudMin “Masters” could be replicated across two, or even three different “master servers” for redundancy. Ideally this should be able to be done across data centers as well for higher redundancy.

If the “master roles” could run on a host server which has XEN instances running as well that would be awesome :slight_smile:


Here’s some “Joe-ese” for you.

when Joe mentions “soon”, he often means a month or two. When he says “a little while”, it’s probably 6 months or more down the road.

I’ll pass along your request to Joe and Jamie, but since he said it’ll be a little while, I’d be surprised to see that feature before the summer this year.



Is it possible to stop & remove CloudMin from the old server, after I have moved everything across to a new master server, without shutting down the whole server, and disrupting the running VM’s on that server?

Yes, that will work fine … shutting down or removing Cloudmin won’t effect running VMs

ok, cool. But how to I actually uninstall CloudMin ?

On a CentOS / Redhat system, you could use the command :

rpm -e wbm-server-manager wbt-virtual-server-theme wbm-security-updates webmin