Last Sunday, I lost the hard drive that contained the upcomging book - everything - images, portraits, texts, even the list of photographers. Fortunately I use a combination of Time Machine and a redundant array Drobo 4X 1 terabyte backup system. Although it took 24 hours to restore all 500 gig. from the lost drive, it came through perfectly. This morning, my fourth drive on the Drobo gave up the ghost, but since the backup is redundant, I simply pulled out the drive and plugged in a spare one, which happened to be twice the size of the other three, no fuss, no muss, nothing lost. It will be a day or two before the new drive is loaded and the redundancy back in force but it doesn't get much more painless than this.
Three cheers for Time Machine and Drobo.