I've noticed this in my syslog recently.  It seems this drive is having a hard time waking up.  Is this something I should be concerned about?

 

Nov 27 15:26:09 Tower kernel: ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen (Errors)
Nov 27 15:26:09 Tower kernel: ata5.00: failed command: READ DMA EXT (Minor Issues)
Nov 27 15:26:09 Tower kernel: ata5.00: cmd 25/00:08:b7:3b:37/00:00:cd:00:00/e0 tag 0 dma 4096 in (Drive related)
Nov 27 15:26:09 Tower kernel:          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) (Errors)
Nov 27 15:26:09 Tower kernel: ata5.00: status: { DRDY } (Drive related)
Nov 27 15:26:09 Tower kernel: ata5: hard resetting link (Minor Issues)
Nov 27 15:26:09 Tower kernel: ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) (Drive related)
Nov 27 15:26:09 Tower kernel: ata5.00: configured for UDMA/133 (Drive related)
Nov 27 15:26:09 Tower kernel: ata5.00: device reported invalid CHS sector 0 (Drive related)
Nov 27 15:26:09 Tower kernel: ata5: EH complete (Drive related)
Nov 27 15:28:05 Tower kernel: mdcmd (53): spinup 2 (Routine)
Nov 27 15:28:05 Tower kernel:  (Routine)
Nov 27 15:28:20 Tower kernel: mdcmd (54): spinup 1 (Routine)
Nov 27 15:28:20 Tower kernel:  (Routine)
Nov 27 15:34:11 Tower kernel: mdcmd (55): spindown 0 (Routine)
Nov 27 15:34:11 Tower kernel: mdcmd (56): spindown 6 (Routine)
Nov 27 15:34:12 Tower kernel: mdcmd (57): spindown 8 (Routine)
Nov 27 16:25:33 Tower kernel: mdcmd (58): spindown 3 (Routine)
Nov 27 16:25:43 Tower kernel: mdcmd (59): spindown 4 (Routine)
Nov 27 16:26:14 Tower kernel: mdcmd (60): spindown 5 (Routine)
Nov 27 16:26:14 Tower kernel: mdcmd (61): spindown 7 (Routine)
Nov 27 16:28:15 Tower kernel: mdcmd (62): spindown 2 (Routine)
Nov 27 16:28:25 Tower kernel: mdcmd (63): spindown 1 (Routine)
Nov 27 18:21:57 Tower kernel: mdcmd (64): spindown 0 (Routine)
Nov 27 18:21:57 Tower kernel: mdcmd (65): spindown 6 (Routine)
Nov 27 18:21:58 Tower kernel: mdcmd (66): spindown 8 (Routine)
Nov 28 08:13:34 Tower kernel: ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen (Errors)
Nov 28 08:13:34 Tower kernel: ata5.00: failed command: IDLE (Minor Issues)
Nov 28 08:13:34 Tower kernel: ata5.00: cmd e3/00:00:00:00:00/00:00:00:00:00/40 tag 0 (Drive related)
Nov 28 08:13:34 Tower kernel:          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) (Errors)
Nov 28 08:13:34 Tower kernel: ata5.00: status: { DRDY } (Drive related)
Nov 28 08:13:34 Tower kernel: ata5: hard resetting link (Minor Issues)
Nov 28 08:13:34 Tower kernel: ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) (Drive related)
Nov 28 08:13:34 Tower kernel: ata5.00: configured for UDMA/133 (Drive related)
Nov 28 08:13:34 Tower kernel: ata5: EH complete (Drive related)

Attach the entire syslog.

Here you go!

syslog-2013-11-28.txt

Try a new SATA cable on disk7.

Thanks.  I opened the case and I think the disk 7 sata cable on the MB was not fully seated.  It's an ASUS motherboard and I'm using one of the raid slots to get 8 ports on the MB.  The problem is that I have backplanes which require right angle cables and all of my SATA cables have the locking feature.  These two ports are not really designed for the locking feature so the plastic housing the cable fits into is stressed and I think it may have caused the cable to works it way out.  I'll keep monitoring it but thanks for the suggestion.