Quote:
but he would feel better if it were also backed up on an independent machine somewhere else in the building.

Raid is not a backup. Raid is for high availability. You have no backup at this point in time.

The best backup systems allow you to go back to when the computer was set up (with less and less granularity) and retreive a file that a user deleted. This makes the whole thing fully auditable. Want to see what the accounting files looked like at two months ago? two years ago? Just load up the right tape, and you're ready to go.

With the drop in hard drive prices, this kind of backup has become less and less prevalent. Instead, you'll usually have n full system backups, going back n times the backup interval. I've never heard of anyone doing a full weekly/monthy/yearly rotation of hard drive backups.

For this reason, if you want a real backup solution, spend the money and get a tape drive with a changer and everything. If you know the shortcomings of a hard drive based system, and feel that your data doesn't warrant a full backup solution, go for the hard drive based system.

Matthew