Duo v2 - Can't add second disc

It seems the kernel is failing to access the device,

Jun  5 11:32:35 nas-A0-99-A9 kernel: In usiHDDpwrctrl_timer_func, power_ing.ID = 1.
Jun  5 11:33:53 nas-A0-99-A9 kernel: scsi 0:0:0:0: Direct-Access     WDC      WD20EARX-00PASB0 51.0 PQ: 0 ANSI: 5
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Sector size 0 reported, assuming 512.
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB)
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] 0-byte physical blocks
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: Attached scsi generic sg1 type 0
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Write Protect is off
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Mode Sense: 23 00 10 00
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Write cache: enabled, read cache: enabled, supports DPO and FUA
Jun  5 11:33:53 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Sector size 0 reported, assuming 512.
Jun  5 11:34:00 nas-A0-99-A9 kernel:  sdb: unknown partition table
Jun  5 11:34:00 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Sector size 0 reported, assuming 512.
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: Device offlined - not ready after error recovery
Jun  5 11:35:46 nas-A0-99-A9 last message repeated 2 times
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Unhandled error code
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Jun  5 11:35:46 nas-A0-99-A9 kernel: end_request: I/O error, dev sdb, sector 8
Jun  5 11:35:46 nas-A0-99-A9 kernel: Buffer I/O error on device sdb, logical block 1
Jun  5 11:35:46 nas-A0-99-A9 kernel: Buffer I/O error on device sdb, logical block 2
Jun  5 11:35:46 nas-A0-99-A9 kernel: Buffer I/O error on device sdb, logical block 3
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Unhandled error code
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Jun  5 11:35:46 nas-A0-99-A9 kernel: end_request: I/O error, dev sdb, sector 3907028992
Jun  5 11:35:46 nas-A0-99-A9 kernel: Buffer I/O error on device sdb, logical block 488378624
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: rejecting I/O to offline device
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Asking for cache data failed
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Assuming drive cache: write through
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: [sdb] Attached SCSI disk
Jun  5 11:35:46 nas-A0-99-A9 kernel: sd 0:0:0:0: rejecting I/O to offline device

If the kernel can't get at the disk, sgdisk won't find it either, sgdisk uses the Linux drivers in order to access the hard drive.
This is not likely to be a software problem, could you try another new disk?

[2012/06/05 11:36:01  2329] dump pt list to /dev/sdb root: 0 
[2012/06/05 11:36:01  2329] index: 1 start=64 end=8388671 last_end=0
[2012/06/05 11:36:01  2329] index: 2 start=8388672 end=9437247 last_end=8388671
[2012/06/05 11:36:01  2329] index: 3 start=9437248 end=3907025072 last_end=9437247
[2012/06/05 11:36:01  2329] LINE 9765: exec command: sgdisk -g -a 8   -n 1:64:8388671 -t 1:FD00 -n 2:8388672:9437247 -t 2:FD00 -n 3:9437248:3907025072 -t 3:FD00 /dev/sdb
Problem opening /dev/sdb for reading! Error is 6.
[2012/06/05 11:36:03  2329] partition copy error /dev/sdb rc = 200
[2012/06/05 11:36:03  2329] sgdisk partition err, verify the disk /dev/sdb again
[2012/06/05 11:36:03  2329] LINE 9648: exec command: sgdisk -p /dev/sdb | grep ' [12] ' > /var/log/frontview/.V_E.source_pt1.sav
Problem opening /dev/sdb for reading! Error is 6.
[2012/06/05 11:36:04  2329]  Sgdisk /dev/sdb partition to file Error. rc = 256
[2012/06/05 11:36:04  2329] Copy partition table FAIL rc=1!!
[2012/06/05 11:36:04  2329] Failed to add disk to md