What would cause "Device not ready (errno=-16), forcing hardreset?
It seems that your hard disk had a hiccup and didn't respond in the time that the kernel wanted. If this is a one time event, I wouldn't worry too much, as it appears that after a reset, the operation completed. If it happens often, I would consider replacing your hard disk. Investigate the smartctl tool to check the health of your hard disk. I hope you are using RAID on this server, so your disk is not a single point of failure.