Hey Scott,
What needs to be backed up? The entire computer? Or just certain files like /etc/passwd and such?
I’d like very much to convince you to keep regular backups of the entire system. You’ll thank me one day. Really, you will.
Doing a entire system backup technically takes another computer to mirror it.
Not at all. Webmin includes a Filesystem Backup module which you can use to archive and compress the entire system into about half its normal size and store it on a remote host.
Here’s our virtualmin.com system partition showing 32GB of disk usage:
/dev/sda3 66G 32G 31G 52% /
And the remotely mounted network storage partition where we backup weekly (full system dump) and nightly (diffs since the previous full backup):
//70.85.125.7/c24907-1
40G 16G 25G 40% /mnt/backup
Note that even keeping a a full backup weekly plus a nightly diff backup only requires about half the space of the uncompressed system usage. The full system backup is a little smaller at 14G:
[[root@www /]]# ls -lh /mnt/backup/
total 16G
-rwxr–r-- 1 1827 1827 2.7G Jan 10 06:21 daily-increments
-rwxr–r-- 1 1827 1827 14G Jan 7 08:13 weekly-full
Most hosting providers will rent you enough space on a network storage device to use for backups for about $10-$30 per month. Ours is stored on the NAS at the host where we keep Virtualmin.com. (Though the new S3 backup feature in Virtualmin is pretty cool, and I suspect we’ll start keeping secondary backups of our most important domains and databases there, too.)
But, since you insist:
Maybe you should define what files should be backed up that might be modified by the installation.
Backup all of /etc in a manner that allows you to easily access anything in it. A tarball in /root is what I’d probably do:
tar czvf etc-backup.tar.gz /etc
Webmin has a backup configuration files feature that can probably substitute for this, though it is specific about what it backs up, and probably doesn’t cover everything we’ll poke at during install.
The config files found in /etc are quite small. A couple of MB, generally, though a Virtualmin system using bandwidth monitoring can push that up a little bit.
Backup your domains using the Virtualmin backup feature. We aren’t going to touch your domains during install, as far as I recall, but we’ll all feel better if you have that data backed up (again, I’d like to convince you to back it up regularly even when not planning an imminent upgrade). The Virtualmin metadata lives in /etc/webmin/virtual-server, so we’ve already got a backup of it…but it won’t hurt to have a fully restorable version of each of your domains.
If you have any packages installed from tarball installed into the normal system paths (/usr/bin, /usr/sbin, /bin, /sbin), then I’d suggest never doing that again. Also back them up, because we’ll probably overwrite them when our RPMs or debs install. This probably doesn’t apply to anyone here, but I’ve seen it done.
I think that’s all we mess with.