My disk4 and parity drives are 6TB. I did a parity check, and this 2 drives are giving me lots of this

Jun 25 21:54:01 Tower kernel: ata8: SATA max UDMA/133 abar m2048@0xf0410000 port 0xf0410180 irq 29

Jun 25 21:54:01 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 25 21:54:01 Tower kernel: ata8.00: ATA-9: WDC WD60EFRX-68MYMN1, WD-WX21D9421P3U, 82.00A82, max UDMA/133

Jun 25 21:54:01 Tower kernel: ata8.00: 11721045168 sectors, multi 0: LBA48 NCQ (depth 31/32), AA

Jun 25 21:54:01 Tower kernel: ata8.00: configured for UDMA/133

Jun 25 21:54:01 Tower kernel: sd 8:0:0:0: [sdh] 11721045168 512-byte logical blocks: (6.00 TB/5.46 TiB)

Jun 25 21:54:01 Tower kernel: sd 8:0:0:0: [sdh] 4096-byte physical blocks

Jun 25 21:54:01 Tower kernel: sd 8:0:0:0: [sdh] Write Protect is off

Jun 25 21:54:01 Tower kernel: sd 8:0:0:0: [sdh] Mode Sense: 00 3a 00 00

Jun 25 21:54:01 Tower kernel: sd 8:0:0:0: [sdh] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA

Jun 25 21:54:01 Tower kernel: sdh: sdh1

Jun 25 21:54:01 Tower kernel: sd 8:0:0:0: [sdh] Attached SCSI disk

Jun 25 21:54:42 Tower emhttp: WDC_WD60EFRX-68MYMN1_WD-WX21D9421P3U (sdh) 5860522584

Jun 25 21:54:42 Tower kernel: md: import disk0: [8,112] (sdh) WDC_WD60EFRX-68MYMN1_WD-WX21D9421P3U size: 5860522532

 

Jun 25 21:54:43 Tower emhttp: shcmd (7): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

Jun 26 00:28:21 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 00:28:21 Tower kernel: ata8.00: failed command: SMART

 

Jun 26 00:28:21 Tower kernel: ata8.00: cmd b0/d0:01:00:4f:c2/00:00:00:00:00/00 tag 14 pio 512 in

Jun 26 00:28:21 Tower kernel: ata8.00: status: { DRDY }

Jun 26 00:28:21 Tower kernel: ata8: hard resetting link

 

Jun 26 00:28:21 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 00:28:21 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 00:28:21 Tower kernel: ata8: EH complete

Jun 26 00:58:59 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 00:58:59 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 00:58:59 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 26 pio 512 in

Jun 26 00:58:59 Tower kernel: ata8.00: status: { DRDY }

Jun 26 00:58:59 Tower kernel: ata8: hard resetting link

 

Jun 26 00:58:59 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 00:58:59 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 00:58:59 Tower kernel: ata8: EH complete

Jun 26 00:59:20 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 00:59:20 Tower kernel: ata8.00: failed command: SMART

 

Jun 26 00:59:20 Tower kernel: ata8.00: cmd b0/d0:01:00:4f:c2/00:00:00:00:00/00 tag 16 pio 512 in

Jun 26 00:59:20 Tower kernel: ata8.00: status: { DRDY }

Jun 26 00:59:20 Tower kernel: ata8: hard resetting link

 

Jun 26 00:59:20 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 00:59:20 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 00:59:20 Tower kernel: ata8: EH complete

Jun 26 01:58:47 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 01:58:47 Tower kernel: ata8.00: failed command: SMART

 

Jun 26 01:58:47 Tower kernel: ata8.00: cmd b0/d1:01:01:4f:c2/00:00:00:00:00/00 tag 30 pio 512 in

Jun 26 01:58:47 Tower kernel: ata8.00: status: { DRDY }

Jun 26 01:58:47 Tower kernel: ata8: hard resetting link

 

Jun 26 01:58:47 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 01:58:47 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 01:58:47 Tower kernel: ata8: EH complete

Jun 26 05:29:40 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 05:29:40 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 05:29:40 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 22 pio 512 in

Jun 26 05:29:40 Tower kernel: ata8.00: status: { DRDY }

Jun 26 05:29:40 Tower kernel: ata8: hard resetting link

 

Jun 26 05:29:40 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 05:29:40 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 05:29:40 Tower kernel: ata8: EH complete

Jun 26 06:00:02 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 06:00:02 Tower kernel: ata8.00: failed command: SMART

 

Jun 26 06:00:02 Tower kernel: ata8.00: cmd b0/d0:01:00:4f:c2/00:00:00:00:00/00 tag 7 pio 512 in

Jun 26 06:00:02 Tower kernel: ata8.00: status: { DRDY }

Jun 26 06:00:02 Tower kernel: ata8: hard resetting link

 

Jun 26 06:00:02 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 06:00:02 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 06:00:02 Tower kernel: ata8: EH complete

Jun 26 11:00:40 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 11:00:40 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 11:00:40 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 24 pio 512 in

Jun 26 11:00:40 Tower kernel: ata8.00: status: { DRDY }

Jun 26 11:00:40 Tower kernel: ata8: hard resetting link

 

Jun 26 11:00:40 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 11:00:40 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 11:00:40 Tower kernel: ata8: EH complete

Jun 26 12:01:04 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 12:01:04 Tower kernel: ata8.00: failed command: SMART

 

Jun 26 12:01:04 Tower kernel: ata8.00: cmd b0/d0:01:00:4f:c2/00:00:00:00:00/00 tag 18 pio 512 in

Jun 26 12:01:04 Tower kernel: ata8.00: status: { DRDY }

Jun 26 12:01:04 Tower kernel: ata8: hard resetting link

 

Jun 26 12:01:04 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 12:01:04 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 12:01:04 Tower kernel: ata8: EH complete

Jun 26 12:31:26 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 12:31:26 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 12:31:26 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 7 pio 512 in

Jun 26 12:31:26 Tower kernel: ata8.00: status: { DRDY }

Jun 26 12:31:26 Tower kernel: ata8: hard resetting link

 

Jun 26 12:31:26 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 12:31:26 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 12:31:26 Tower kernel: ata8: EH complete

Jun 26 15:02:16 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 15:02:16 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 15:02:16 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 3 pio 512 in

Jun 26 15:02:16 Tower kernel: ata8.00: status: { DRDY }

Jun 26 15:02:16 Tower kernel: ata8: hard resetting link

 

Jun 26 15:02:16 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 15:02:16 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 15:02:16 Tower kernel: ata8: EH complete

Jun 26 18:33:50 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 18:33:50 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 18:33:50 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 5 pio 512 in

Jun 26 18:33:50 Tower kernel: ata8.00: status: { DRDY }

Jun 26 18:33:50 Tower kernel: ata8: hard resetting link

 

Jun 26 18:33:50 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 18:33:50 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 18:33:50 Tower kernel: ata8: EH complete

Jun 26 20:04:36 Tower kernel: ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen

 

Jun 26 20:04:36 Tower kernel: ata8.00: failed command: IDENTIFY DEVICE

 

Jun 26 20:04:36 Tower kernel: ata8.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 22 pio 512 in

Jun 26 20:04:36 Tower kernel: ata8.00: status: { DRDY }

Jun 26 20:04:36 Tower kernel: ata8: hard resetting link

 

Jun 26 20:04:36 Tower kernel: ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

Jun 26 20:04:36 Tower kernel: ata8.00: configured for UDMA/133

Jun 26 20:04:36 Tower kernel: ata8: EH complete

Jun 26 20:48:31 Tower emhttp: shcmd (47): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

Jun 26 20:50:31 Tower emhttp: shcmd (53): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

Jun 26 21:14:09 Tower emhttp: shcmd (59): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

Jun 26 21:16:10 Tower emhttp: shcmd (65): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

Jun 26 21:19:11 Tower emhttp: shcmd (71): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

Jun 26 21:19:17 Tower emhttp: shcmd (77): /usr/local/sbin/set_ncq sdh 1 &> /dev/null

 

I did a search and it appears to be some loose cable or spoilt cable but I've already double checked. The only possible reason is that this two are running on a sata card instead of the ones from the motherboard but it can't be that of a coincidence. I'm thinking that half the command errors appears mostly when I access the main page and the drive info page (which loads smart information) while the parity is going on, so is it possible that the drives are busy that's causing these errors or there's something different with the 6TB drives? After the parity check was done, I no longer see such errors appearing on the two drives. I'm running a extended test of both drives now just in case. Both are WD Red. The closest I could find is http://askubuntu.com/questions/24325/is-a-disk-ata-timeout-exception-dangerous

Swap one of the two 6TB drives off of that SATA card.  (unRAID identifies drives by their serial numbers, not where they are connected to.  So you can just swap two of the SATA data leads.) 

 

Setup the same test conditions and see if you get the same errors.

 

If this does not answer your questions, post up the card info and a Diagnostics file. 

Are you obsessively neat with your cable layout? It could be crosstalk between SATA cables. Try making their layout more random. What is your SATA card? Have you tried reseating it? Post diagnostics. What is your power supply and power distribution? Beware faulty power splitters. Many otherwise unexplained oddities can be cleared up by fitting a better power supply.

 

You didn't provide much info, just an excerpt that's well after the initial errors, which are ALWAYS the most important and useful.  It's always best to provide the complete diagnostics (which has the complete syslog).

 

What I can see above is communications are down between the kernel and the driver.  Lack of response to Identity or SMART inquiries means the drive isn't responding.  If they were there, they would answer, identify themselves and provide requested SMART info.  But without the earlier part of the syslog, can't tell how they quit or why they were dropped by the system.

 

I can't tell without more info whether the drives were lost simultaneously.  2 drives are essentially never lost simultaneously, so when it happens, it is almost always not their fault, but the fault of the controller or a power issue or something else common to both.  The most likely is that the controller faulted.