Bit of backgorund:
Having got webmin/virtualmin working on a new vps, and my website all up and running I now want to decide on a backup/migrate strategy. I reckon a full file / down backup will not be much use. I already have a vps image on my vps host. I could restore that if the vps dies. My websites already backup their databases and files. But what happens if the vps company goes out of business. The image I've taken is no use as that's gone too. I'd need to start from a new OS and rebuild so basically a migration.
So I tried the method on http://www.virtualmin.com/documentation/system/migrate and also took a webmin config backup for all modules.
I restored the webmin config. This did NOT change the theme but it did set up the virtual servers, but not the home folders (maybe I should have backed up every webmin module except virtualmin).
I restored virtualmin as it says in the page. The ftp restore failed which I ignored and went on to the second stage (2nd line of the 2 restore commands). This failed with
Restoring Apache virtual host configuration .. .. no Apache virtual host found!
Is this because I let it change the ip address at the webmin restore?
What is the correct procedure to do a full migrate, webmin and virtualmin and web sites?
What your VPS company provides is probably a snapshot and if that is the case be aware that is not a full backup and its useless if the node/hardware crashes.
What most VPS companies provide are just state snapshots, this allows you to recover the state of the VPS but you should be aware of the danger of relying on that as backup, because its not only if your VPS company goes out of business that you will lose it, if the node/hardware/server where your VPS is has a problem that snapshot is useless as well. This means that if they have to restore the node, server or it has a problem in their side, or just did some faulty upgrade on their side, your snapshot could be invalid as it needs the full state of your machine to work. This means that without your full VPS the snapshot is useless. Tons of people lose data like this in particular because some companies promote or sell that as a backup. The truth is that when they have a crash or problem with their hardware, your backup is trash, you cannot recover or use it on a new server either. Most of the cases it does not even work in the same machine if they had to do some recovery and of course not if they had to make a clean install.
This means, I would seriously ask or research if what your VPS company is providing is a full backup state of the VPS or image, then you should be able to download it, if its not, or they tell you you can't download the image then its the just a state snapshot and while that allows you to do a fast recovery PLEASE don't rely on that for your data protection. If its a full image, you can take it and use it in any provider and that is a full backup but don't just rely on one. It can be corrupted or faulty and you should test them from time to time.
To answer your question directly. I would do a full backup of the webmin modules, and virtualmin (note that webmin already does this). If you have all the files and important data, plus your files and database you should be good to go. Just make the backup to an external place always. Not in your same VPS and not in another VPS in the same company. Use another provider, this way your are going to be able to recover even if your provider has problems or there is a critical problem with the datacenter.
That was sort of my point. The snapshot of my vps is a quick re-install, but not regularly updated so I'd need to also restore my daily database backups and my weekly site file backups. But a snapshot is no good if my vps company has gone to the wall. So I need another method, more like a migrate.
So far I'm not having much success try to restore a clean OS with a new webmin/virtualmin install to be the same as my current set up by doing a backup on the current set up and then a restore of these files on the new setup.
See the latest in this thread https://www.virtualmin.com/node/34103
Since both these threads seem to have drift together, being a report of webmin/virtualmin migrate not working, I'll drop this one.