Preclear failure on 4 TB Seagate DM - Is it the controller or the disk?

I just had a preclear fail on a 4 TB Seagate DM drive mid-way through the process. (Syslog attached along with the three reports generated by preclear for drive sdg and a SMART report. Another drive was also being precleared so it also appears in the log but can be ignored. The action happens between lines 1340 -1676 - from 09:36:43 to 9:52:00)

The drive was attached to a Supermicro SASLP-MV8 with .15 firmware, in a x16 slot on a GIGABYTE GA-MA785G-UD3H mother board, that has already shown some peculiarities regarding support for 4 TB drives and this card. (see http://lime-technology.com/forum/index.php?topic=26391.0 for details.)

This drive had already completed one preclear cycle in the same slot without problem. This time the preclear process encountered problems and seems to have aborted at around 18 hours in. The mymain addon no longer showed the drive as existing (there is no line entry for it as a drive not in the array).  There was an entry for it in the /dev directory.

I let the other drive complete its preclear successfully, and then rebooted. The drive now shows up again in mymain as a drive not included in the array, but with the following SMART data (full report in zip file.)

197 Current_Pending_Sector  0x0012  100  100  000    Old_age  Always      -      16

198 Offline_Uncorrectable  0x0010  100  100  000    Old_age  Offline      -      16

These bad sectors were not there after the first preclear on the drive, or at the beginning of this second preclear.

Is there anything in the attached log that provides a clue as to whether the Supermicro Card, the MB or the drive is the culprit. Is this at all typical of how a preclear fails  (in other words would preclear typically abort or just report the problem at the end) on a bad drive  or is this more likely something that was caused by the Supermicro card perhaps in conjunction with the MB. Given the peculiarities I've already encountered between this board and the Supermicro card when dealing with 4 TB drives, I'm unsure about how to evaluate these results.

Thanks for any help

Harry

syslog_plus.zip