Class action lawsuits are being filed against Seagate over the high rate of failure on their hard drives. The suit specifically claims the 3tb sized drives.
http://www.techspot.com/news/63672-s...tive-hard.html
per the article there is hard data that supports lawsuit's claim: Cloud company BackBlaze published failure rate of close to 50 thousand hard drives they used in the past 3 years. It looks like the 1.5tb also have a high failure rate.