Using Rsync to do local snapshotting/backups January 9, 2010Jeff Atwood's recent data-loss story is a good reminder of why you should do off-site backups. But what if you just accidentally rm'ed a file, or saved over it's contents with bad data? It's a lot of work to do a full backup recovery of your entire system just to get back one file. Isn't there an easier way?
Local Snapshotting: not perfect, but super usefullHere's what I do: run rsync with cron to copy all your important files to a local /backup directory.
First, create a new file called crontab.txt with contents like:
@hourly rsync -a --inplace --max-size=1MB /www /etc /backup/hourly/ @daily rsync -a --inplace --max-size=1MB /www /etc /backup/daily/ @weekly rsync -a --inplace --max-size=1MB /www /etc /backup/weekly/ @monthly rsync -a --inplace /www /etc /backup/monthly/
Let me explain:
- @hourly (and the others) is a special interval understood by cron
- /www and /etc are specific directories I want to keep snapshotted. You might want to include /home as well
- The -a option to rsync tells it to do "archive" mode (preserving permissions, etc...)
- The --inplace option is just an optimization so that files in /backup are overwritten inplace, as opposed to rsync creating an intermediate temp file.
- The --max-size=1MB tells rsync to ignore files greater than 1MB in size. I do this so that I don't bother making lots of copies of big log files and videos and other stuff that isn't that important and doesn't change that often.
Now you install this crontab by doing:
crontab crontab.txtI do this as the root user, but you can do this as any user that can read all the directories you need to backup, and can write to /backup. (Warning: the above command will overwrite any other crontabs you already have installed. Do a crontab -l first, to see what's installed.) Now you can just sit back and relax -- copies of your local files are being copied every hour, day, week, and month to the /backup directory. If you want to make sure you have a full (monthly) backup right away, then you should execute:
rsync -a --inplace /www /etc /backup/monthly/right now.
How does this help me?Let's say you just accidentally removed a local file
rm /etc/lighttpd/lighttpd.conf # Oh shit, I didn't mean to do that!Not to fear, you can recover it by doing
cp /backup/hourly/etc/lighttpd/lighttpd.conf /etc/lighttpd/lighttpd.conf