Are USB hard disks less reliable for backups?

Solution 1:

I suppose this could happen, but then again your RAID controller within your server could fail, or the Fiber Channel card that runs to your tape drive, or your tape drive itself could go bad. A consumer USB drive obviously isn't going to be as technically robust as enterprise level hardware, but if your short on funds it's better than nothing. I'd be more worried about the drive itself failing before I'd ever worry about the USB controller going out.

While I wouldn't recommend using USB disks permanently, for a short term backup solution they're fine and the price is right. The biggest downside is their speed, large files take forever.

USB disks + robocopy = low cost backups for many small businesses

I should also state, robocopy verifies the files it copies via checksum on the fly, so if things were to get scrambled on the way to the external drive, it would alert you

And to clarify, I am not saying anyone should avoid USB backups. They are a easy and cheap solution for backups as long as the data stays under 2TB. Go beyond that and backups take too long, and you'll hit your next backup cycle before the last one has a chance to finish.