If you've worked hard to configure your Linux machine and can't afford to lose it due to drive failure, try creating an image of it using dd periodically.
It wouldn't make much sense to store the image of the drive on the drive itself, but luckily dd is smart and you can combine it with ssh and gzip to store your stuff off-site.
# dd if=/dev/sda | ssh firstname.lastname@example.org dd of=/backup/drive.img.gz
At this point the drive.img.gz file is quite large. If you're going over the internet this will take a really long time and kill your bandwidth.
# dd if=/dev/sda | gzip | ssh email@example.com dd of=/backup/drive.img.gz
Notice the gzip pipe right before the ssh command compressing the stream before it gets sent to backup.remotehost.com. You can also tell dd to create an image of a specific partition only (specify /dev/sda2 as the input stream)
To restore a drive image, log into backup.remotehost.com and type:
# dd if=/backup/drive.img.gz | gzip -d | ssh firstname.lastname@example.org dd of=/dev/sda
You should only restore to a drive that is not in use (possibly an OS running off of a Live CD?).
Warning: These commands are not idiot-proof and it's all too easy to wipe the wrong drive!
I was able to reduce my drive.img.gz by almost 75% using gzip! You may find other compression tools to be better or worse depending on the data you are imaging.
Recently I was working on a project where we configured secure MySQL replication between Fedora host A and Fedora host B. There was no RAID or any kind of redundancy and me being paranoid I quickly imaged drive B to drive A and vice-versa.