[gentoo-server] backups/mirroring with rsync

[Ben Munat]

Hello,

So, I decided to keep things "simple" and just use rsync for backing up 
my web server. But now I'm wondering if "simple" was the right word... 
my head is spinning with all the possible configuration and command-line 
argument permutations. Below is my plan... if there are any rsync 
experts out there, I'd love to hear thoughts, warnings, advice, etc.

I'm only using about 5 gigs on my server's drive. I have 50 gigs 
available on one partition alone on my home machine, so I'm planning on 
mirroring the server into a chroot on my home machine. My IP address has 
only changed once in the last four years, so that shouldn't be an issue.

The initial sync will suck, but after that it shouldn't be too bad... 
not that much activity on this server. I'm figuring on setting up an 
hourly cron job on the server to run rsync. I'll also set up a user on 
my local machine just for this and have rsync chroot into that user's 
home directory.

Then I'll just have the rsync start from "/" on the server. It doesn't 
seem like that much data to mess with picking and choosing. Plus, my 
hope is that if I should ever need this backup, I could just have the 
hosting company run my server from the gentoo cd and rsync the backup 
back onto the new drive.

One question I have, however, is whether I need to exclude the /proc 
filesystem from the backup? Would that cause problems if I restored from 
the backup and then tried to boot the restored system? Or, hmmm, 
actually the /proc files are recreated on boot, right?

Someone told me that having the rsync server running on both machines 
makes things go faster... though I'm not clear on how you do that. Is 
this as simple as adding the "--server" option to the command? I was 
also planning on doing this over ssh to get encryption and to get 
through my firewall.

So, here's what I think I need to do:  Make my new user on my local 
machine (say, "backup-user", for example), giving him a home dir (/home 
is on it's own partition with 50 gigs free). Then I set up the 
rsyncd.conf file on my local machine with a module called, for example, 
"server-backup", give it the path "/home/backup", and say, "use 
chroot=yes". I suppose I could also put in a "hosts allow" clause with 
my server's IP address.

Then, on the server, I put a script in the cron.hourly folder that just 
says something like:

rsync -az -e ssh --delete --server --password-file=~secret / 
backup-user@<my ip address>::server-backup

(but all on one line...)

If I've got this right, that would tell rsync to use "archive" mode 
(preserving permissions and ownership) and compression. It would then 
connect over ssh to my home machine as "backup-user", getting the 
password from a (chmod 600!) file called "~secret", and sync everything 
under "/" on the server into "/home/backup-user" (which is the path for 
the "server-backup" rsync module), chrooted in that directory.

Oh crap... I just noticed that the man page says, if I'm understanding 
it correctly, that chroot isn't available unless I connect as root. That 
seems dumb... rsyncd is running as root on my machine, it should be able 
to chroot. Not that I really need the chroot I guess... I'm allowing 
only my server to connect, so I suppose I'll just skip that.

Anyway, sorry this is so long... but I wanted to make sure I have this 
all correct before I go trying anything. Though, I suppose I'll use that 
"-n" dry-run option before actually doing this anyway.

Well, thoughts and observations much appreciated...

Ben