(My question here is specifically about Ubuntu, but I'm posting it on Unix & Linux because I think the answer will apply to Linux in general. I'm more than happy to reformat the question or move it altogether to Ask Ubuntu if necessary.)
I'm running a VPS (Ubuntu Server 15.04) and I need to remove/recreate it for housekeeping purposes. I've started looking over this guide for creating a complete tar backup. Before I start, however, I have several questions.
First, running the backup itself. I started the backup using the command
sudo tar -cvpzf backup.tar.gz --exclude=/backup.tar.gz --one-file-system /. It errored out while running, however, with the error
tar: /: file changed as we read it. How do I avoid this problem? I'm not running anything critical, so anything that changes can be ignored--using either the old or the new version is fine. Is there a way to make tar just try again to read the specific file that changed?
Next, that guide assumes that the device can be booted from live media, which I cannot do with my VPS provider. I will actually have to reimage the system with Ubuntu Server 14.04. Will I be able to simply put the full backup tar at the root, then run
sudo tar -xvpzf /backup.tar.gz --numeric-owner? I feel like this wouldn't work since I'd be overwriting OS files, but I'm not sure.
My final question involves the fact that I'll be reimaging with Server 14.04. Both will be x64, so that's not an issue, but, assuming the second question above is answered and works, is it okay to completely overwrite 14.04 with my full 15.04 backup? It doesn't matter to my VPS provider, I know that, I just don't know if 15.04 over 14.04 would create an issue.
If taking a tar backup wouldn't be the best method in this scenario, is there a better alternative?