I've been reading about backup solutions and have come across a number of people saying they use a USB external hard drive as part or all of their backup solution.
Are USB hard drives really sufficiently reliable to use for backups? From what I read in the past (e.g., http://blogs.computerworld.com/why_im_done_with_portable_hard_drives) they are rather failure-prone, especially apparently USB-only ones where the USB controller electronics have a high failure rate. Personally, I've only ever had one, a mid-price Western Digital, which has had some issues and I stopped using.
I understand there are some factors that substantially affect reliability, which AFAIK are whether the drive is moved much, whether it has its own power supply, and whether it has adequate cooling. Perhaps the drives are more reliable now than they used to be? Perhaps if they last through an break-in initial period they then tend to be reliable?