If your seeing funny blinking lights on the drive, and you are not the only person having problems with this particular drive model, I would be very suspicious that a drive firmware bug is being tickled. The best solution in this case would be to obtain a better version of the firmware from the vendor, but lacking that you might try turning off tagged command queueing or just reducing the number of tagged openings. I've noticed interactions between tagged command queueing and write caching on Seagate drives, so you might try turning off write caching and leaving the number of tagged openings alone. You can do all this with camcontrol.