Right now, there seems to be one canonical hard-drive tag, with 901 questions. There are also questions tagged disk and shudder hard disk. Yes, that's hard and disk. Should they all be retagged into hard-drive?
Yes, consistency is a good thing, and
hard-drive looks to be the standard form in this case. I've retagged questions under
hard-drive. There are a good number under
disk though, I wonder if a moderator can use their mass-retag powers on those questions.
disc seems to be used in the context of CD and DVD, not so much hard drives.