I have an external drive and a big NAS box which I back up to daily. The NAS holds 30 days of backups. About a year ago I went to add more photos I recently took to my photo albums, and while I was there I thought I'd check out some older photos while the data transferred across. All 30 days of my photos were corrupted. I lost about 10 years of photos. And to top it off, the backup on the external drive which only holds my photos and music was corrupted. Note, not the drive or the entire contents. Just the photos. My wife loves bringing it up to watch me fume.