The W icon in the drive activity icon is not related to drive failure.

Not directly, but he did say that his W would appear and then stay up for several minutes at a time, which is not normal. I suppose if communication with the drive failed at just the right moment, it could stay up like he said.

I don't think this is mntioned in the FAQ.

You're right, it's not. I don't think anyone's ever asked a question on that one.