To phrase this another way: Do you have backups? That work? Are you sure?
Having proper backups is your insurance policy against theft, fire, accidental damage, etc. for all of your photos, code, blogs, letters to your parents, whatever. If your house burned down today, what would you lose?
Learn from the mistakes of others by observing the case study in abject backups FAIL that is journalspace. I hope they didn’t have investors, because that kind of completely boneheaded failure would have me looking up the words fiduciary duty.
For those who don’t understand RAID, I’ll explain it simply: RAID is not a backup. Ever. Anyone who tells you differently is a) lying, and b) probably selling something. All RAID does it keep your computer running if one of its disks dies. This doesn’t happen all that much when you only have a couple of disks. I’ve had 1 disk fail in my home servers in 15 years. Most of the time, you need backups to recover from humans doing stupid things. I do stupid things all the time. I’m special because I know that I do this, so I’ve set things up so that I can recover from doing stupid things occasionally.
Now is a good time to review Jamie Zawinski’s excellent advice. It’s really not that hard, or expensive, to have solid backups that work.
RAID can be even more complex than that, and, quite frankly, if you don’t understand it, don’t use it and blindly assume everything will be fine. Either learn what you’re doing, leave it to someone who does know (I am one of those people), or lose all of your data. Those are your only choices.