Testimonial (part 6: conclusion):

This experience taught me several things about using external hard drives to preserve valuable data. First, drives can fail in several "invisible" ways that don't come to light until you need them to work and they don't. Second, twelve copies was just barely enough to preserve my archive. Third, IdeaFarm (tm) Archive Healer is good for revealing early transient failures to identify devices that are likely to fail catastrophically soon.