Drivepool devices: Thank you! That'll be awesome.
/dev/sdb: After much testing, I realised that the correct SMART attributes show up about half of the time smartctl is run. Sometimes the result is normal, sometimes it all shows up as UNKNOWN with weird Raw Values. I'm stumped.
/dev/sdd: I've sort-of given up on /dev/sdd. Interesting thing was I got the following result after using the -d ata option.
I hadn't disabled SMART as it says, but I've tried enabling it again. BUT the same result is shown. Perhaps it's a limitation of the controller.
smartctl 6.3 2014-07-26 r3976 [i686-w64-mingw32-2012r2(64)] (sf-6.3-1)
Copyright (C) 2002-14, Bruce Allen, Christian Franke,
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Caviar Green (AF, SATA 6Gb/s)
Device Model: WDC WD40EZRX-00SPEB0
Serial Number: DCC4E0759680
Firmware Version: [No Information Found]
Device is: In smartctl database [for details use: -P show]
ATA Version is: [No Information Found]
Local Time is: Fri Nov 07 18:06:37 2014 CST
SMART support is: Available - device has SMART capability.
Enabled status cached by OS, trying SMART RETURN STATUS cmd.
SMART support is: Disabled
SMART Disabled. Use option -s with argument 'on' to enable it.
(override with '-T permissive' option)