mmcgrath: there it is.
jsoft: please attempt to follow the rules outlined in the channel topic.
jsoft: that shows that a drive has been removed from your array for being faulty
jsoft: smartctl will confirm if the drive sucks, at which point you can replace it, or enable it and rebuild the array
note that this is not an IO error message, simply a drive failure message from your raid manager.
you'll probably have other IO error messages in /var/log/messages