Using backup software that may refuse to work for licensing resons when you need it is reckless.
mr. poopyhead wrote:
one of the drives in my mirror died
I don't understand your problem. If you have mirrors then you should have a way to copy your data properly!
Microsoft has a utility called robocopy which is designed to mirror files. It's supposed to preserve permissions but I don't remember if it can verify.
I've also used a third-party utility called XXCOPY. The xcopy utility included in Windows may do the job as well. And I've used rsync on Windows a lot(there's a package called cwrsync if you don't want to install cygwin). These utilities can verify but I don't recall if and how they handle permissions.
There's more than one way you can end up with corrupted files so I do recommend "hashing the entire drive" actually. That's what copy utilities will do if they have a proper verify function anyway.
If you create hashes at the file level or lower and keep them around, you'll be able to verify your copy with only the target drive connected. But the main point is that you'll be able to detect corruption regardless of what caused it in the future (bug, bad RAM, user error, malware and so on) as well as verify copies faster.