Without a pre-reboot syslog we can't see what happened, but the disk looks healthy so you'll need to rebuild, either using a new disk or the old disk, since you have dual parity it's not so risky to use the old one, just make sure that the contents of the emulated disk look correct, since whatever's there is what's going to be on the rebuilt disk, also I would recommend swapping/replacing cables/backplane slot just to rule that out in case the same disk fails again.