Raid 1 software failed

If you want to keep it simple, just drag and

If you want to keep it simple just drag and drop, given there's no corruption on the drive it should copy over fine. For something more robust, use the "rsync" command line command if you are comfortable working in Terminal. For a professional utility I always recommend Chronosync, very reliable and full featured back/restore/mirror software. And though it's not free but definitely worth the money, pay once and updates are free for life. I have it handy for just such jobs like you've encountered, when I need to copy large amounts of data across the network or between devices with confidence. Also a great alternative to Time Machine.