Well, it just happened again, but at least I'm home this time.

I'm still puzzled as to what it is though. Rebooted and the drives again are just fine.

This is the log excerpt.

Code:
Jul 20 03:47:02 dbase kernel: imklog 4.6.2, log source = /proc/kmsg started.Jul 20 03:47:02 dbase rsyslogd: [origin software="rsyslogd" swVersion="4.6.2" x-pid="1380" x-info="http://www.rsyslog.com"] (re)start
Jul 21 15:21:54 dbase kernel: ata8.00: exception Emask 0x0 SAct 0x7fffffff SErr 0x0 action 0x6 frozen
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:00:87:03:53/00:00:0c:00:00/40 tag 0 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:04:3f:00:00/00:00:00:00:00/40 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:08:07:d5:52/00:00:0c:00:00/40 tag 1 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:10:4f:e5:52/00:00:0c:00:00/40 tag 2 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:18:9f:dc:52/00:00:0c:00:00/40 tag 3 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:20:f7:ec:52/00:00:0c:00:00/40 tag 4 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:28:a7:e4:52/00:00:0c:00:00/40 tag 5 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:30:1f:d9:52/00:00:0c:00:00/40 tag 6 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/10:38:bf:e4:52/00:00:0c:00:00/40 tag 7 ncq 8192 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:40:4f:d7:52/00:00:0c:00:00/40 tag 8 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 21 15:21:54 dbase kernel: ata8.00: status: { DRDY }
Jul 21 15:21:54 dbase kernel: ata8.00: failed command: WRITE FPDMA QUEUED
Jul 21 15:21:54 dbase kernel: ata8.00: cmd 61/08:48:67:da:52/00:00:0c:00:00/40 tag 9 ncq 4096 out
Jul 21 15:21:54 dbase kernel:         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
<snip>
Jul 21 15:22:41 dbase kernel: ata8.00: device reported invalid CHS sector 0
Jul 21 15:22:41 dbase kernel: ata8: hard resetting link
Jul 21 15:22:41 dbase kernel: ata8: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
Jul 21 15:22:41 dbase kernel: ata8: EH complete
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Unhandled error code
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] CDB: Write(10): 2a 00 0c 52 fd 8f 00 00 08 00
Jul 21 15:22:41 dbase kernel: end_request: I/O error, dev sdd, sector 206765455
Jul 21 15:22:41 dbase kernel: Buffer I/O error on device sdd1, logical block 25845674
Jul 21 15:22:41 dbase kernel: lost page write due to I/O error on sdd1
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Unhandled error code
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] CDB: Write(10): 2a 00 0c 52 db 6f 00 00 08 00
Jul 21 15:22:41 dbase kernel: end_request: I/O error, dev sdd, sector 206756719
Jul 21 15:22:41 dbase kernel: Buffer I/O error on device sdd1, logical block 25844582
Jul 21 15:22:41 dbase kernel: lost page write due to I/O error on sdd1
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Unhandled error code
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] CDB: Write(10): 2a 00 0c 52 b2 bf 00 00 08 00
Jul 21 15:22:41 dbase kernel: end_request: I/O error, dev sdd, sector 206746303
Jul 21 15:22:41 dbase kernel: Buffer I/O error on device sdd1, logical block 25843280
Jul 21 15:22:41 dbase kernel: lost page write due to I/O error on sdd1
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Unhandled error code
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 21 15:22:41 dbase kernel: sd 7:0:0:0: [sdd] CDB: Write(10): 2a 00 0c 52 da 57 00 00 08 00
Jul 21 15:22:41 dbase kernel: end_request: I/O error, dev sdd, sector 206756439
Jul 21 15:22:41 dbase kernel: Buffer I/O error on device sdd1, logical block 25844547
Lots of that then similar for sdc1

I'm going to at least put in the other 2 drives I have spare right now.