Hardware failure
When my two external Time Machine hard drives gave out a month ago one after the other within weeks, both only 2 years old, I thought this was bad luck. I bought two new WD drives, and now, one has the same hardware failure! Disk Utilty can't repair it, DiskWarrior says "Directory cannot be rebuilt due to a hardware failure (-36, 2747)".
Is my MBP killing these drives? I can't believe this is happening just by accident!