More fun. Finally cleaned off enough space on several other hard drives to copy everything off the 1T Toshiba drive. Then removed and recreated the partition and formatted the drive for NTSF Windows 7 (Computer Management app). The My Cloud now appears mount the drive in read/write mode just like it should. Yay. 
Now the bad is copying everything back to the drive. Boo. 
Still non clue why the drive, in its out of the box formatting, would not mount properly with the OS3 firmware. If reformatting is the solution to the 0K and not being mounted properly, others may not want to take the time to backup existing content on their drives to reformat.
Some more data.
First a mount -l from earlier in the day when the drive was being mounted in read only mode.
WDMyCloud:~# mount -l
/dev/sdb1 on /var/media/Toshiba1T type ufsd (ro,relatime,nls=utf8,uid=65534,gid=1000,fmask=0,dmask=0,force,user_xattr) [Toshiba1T]
/dev/sdb1 on /nfs/Toshiba1T type ufsd (ro,relatime,nls=utf8,uid=65534,gid=1000,fmask=0,dmask=0,force,user_xattr) [Toshiba1T]
And now the latest when the drive was mounted in read/write mode.
WDMyCloud:~# mount -l
/dev/sdb1 on /var/media/Toshiba type ufsd (rw,relatime,nls=utf8,uid=65534,gid=1000,fmask=0,dmask=0,force,user_xattr) [Toshiba]
/dev/sdb1 on /nfs/Toshiba type ufsd (rw,relatime,nls=utf8,uid=65534,gid=1000,fmask=0,dmask=0,force,user_xattr) [Toshiba]
WDMyCloud:~# fdisk -l /dev/sdb
Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x1eaa4a81
Device Boot Start End Blocks Id System
/dev/sdb1 2048 1953521663 976759808 7 HPFS/NTFS/exFAT
WDMyCloud:~# dmesg | tail
[17999.461547] /files/sq_kernel/linux/drivers/usb/core/inode.c: creating file '004'
[18004.962892] scsi 4:0:0:0: Direct-Access TOSHIBA External USB 3.0 0001 PQ: 0 ANSI: 6
[18004.971846] sd 4:0:0:0: Attached scsi generic sg1 type 0
[18004.978601] sd 4:0:0:0: [sdb] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
[18004.989987] sd 4:0:0:0: [sdb] Write Protect is off
[18004.994834] sd 4:0:0:0: [sdb] Mode Sense: 33 00 00 08
[18005.000853] sd 4:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[18005.036832] sdb: sdb1
[18005.046685] sd 4:0:0:0: [sdb] Attached SCSI disk
[18008.072828] ufsd: "mount" (sdb1): is mounted as NTFS (without journal)
From the kern.log (system report dump):
2016-02-06T18:19:50.987287-05:00 di=NqJQ6FTJD8 debug kernel:[17999.067106] hub 2-0:1.0: state 7 ports 1 chg 0000 evt 0002
2016-02-06T18:19:50.987347-05:00 di=NqJQ6FTJD8 debug kernel:[17999.072665] hub 2-0:1.0: port 1, status 0203, change 0001, 5.0 Gb/s
2016-02-06T18:19:51.057303-05:00 di=NqJQ6FTJD8 debug kernel:[17999.235754] hub 2-0:1.0: debounce: port 1: total 100ms stable 100ms status 0x203
2016-02-06T18:19:51.177294-05:00 di=NqJQ6FTJD8 info kernel:[17999.355784] usb 2-1: new SuperSpeed USB device number 4 using xhci-hcd
2016-02-06T18:19:51.198754-05:00 di=NqJQ6FTJD8 debug kernel:[17999.376414] usb 2-1: skipped 1 descriptor after endpoint
2016-02-06T18:19:51.198823-05:00 di=NqJQ6FTJD8 debug kernel:[17999.381764] usb 2-1: skipped 1 descriptor after endpoint
2016-02-06T18:19:51.217354-05:00 di=NqJQ6FTJD8 debug kernel:[17999.387575] usb 2-1: default language 0x0409
2016-02-06T18:19:51.217396-05:00 di=NqJQ6FTJD8 debug kernel:[17999.392228] usb 2-1: udev 4, busnum 2, minor = 131
2016-02-06T18:19:51.217413-05:00 di=NqJQ6FTJD8 info kernel:[17999.397080] usb 2-1: New USB device found, idVendor=0480, idProduct=a006
2016-02-06T18:19:51.217427-05:00 di=NqJQ6FTJD8 info kernel:[17999.403821] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
2016-02-06T18:19:51.231217-05:00 di=NqJQ6FTJD8 info kernel:[17999.411021] usb 2-1: Product: External USB 3.0
2016-02-06T18:19:51.231252-05:00 di=NqJQ6FTJD8 info kernel:[17999.415493] usb 2-1: Manufacturer: Toshiba
2016-02-06T18:19:51.231265-05:00 di=NqJQ6FTJD8 info kernel:[17999.419626] usb 2-1: SerialNumber: 2011111316674
2016-02-06T18:19:51.239884-05:00 di=NqJQ6FTJD8 debug kernel:[17999.424575] usb 2-1: usb_probe_device
2016-02-06T18:19:51.239929-05:00 di=NqJQ6FTJD8 debug kernel:[17999.428294] usb 2-1: configuration #1 chosen from 1 choice
2016-02-06T18:19:51.251068-05:00 di=NqJQ6FTJD8 debug kernel:[17999.433947] usb 2-1: Successful Endpoint Configure command
2016-02-06T18:19:51.258192-05:00 di=NqJQ6FTJD8 debug kernel:[17999.439685] usb 2-1: adding 2-1:1.0 (config #1, interface 0)
2016-02-06T18:19:51.258241-05:00 di=NqJQ6FTJD8 debug kernel:[17999.445772] usb-storage 2-1:1.0: usb_probe_interface
2016-02-06T18:19:51.268193-05:00 di=NqJQ6FTJD8 debug kernel:[17999.450810] usb-storage 2-1:1.0: usb_probe_interface - got id
2016-02-06T18:19:51.280608-05:00 di=NqJQ6FTJD8 info kernel:[17999.457244] scsi4 : usb-storage 2-1:1.0
2016-02-06T18:19:51.280672-05:00 di=NqJQ6FTJD8 debug kernel:[17999.461547] /files/sq_kernel/linux/drivers/usb/core/inode.c: creating file '004'
2016-02-06T18:19:56.782701-05:00 di=NqJQ6FTJD8 notice kernel:[18004.962892] scsi 4:0:0:0: Direct-Access TOSHIBA External USB 3.0 0001 PQ: 0 ANSI: 6
2016-02-06T18:19:56.789256-05:00 di=NqJQ6FTJD8 notice kernel:[18004.971846] sd 4:0:0:0: Attached scsi generic sg1 type 0
2016-02-06T18:19:56.798133-05:00 di=NqJQ6FTJD8 notice kernel:[18004.978601] sd 4:0:0:0: [sdb] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
2016-02-06T18:19:56.811614-05:00 di=NqJQ6FTJD8 notice kernel:[18004.989987] sd 4:0:0:0: [sdb] Write Protect is off
2016-02-06T18:19:56.811669-05:00 di=NqJQ6FTJD8 debug kernel:[18004.994834] sd 4:0:0:0: [sdb] Mode Sense: 33 00 00 08
2016-02-06T18:19:56.822090-05:00 di=NqJQ6FTJD8 notice kernel:[18005.000853] sd 4:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
2016-02-06T18:19:56.857440-05:00 di=NqJQ6FTJD8 info kernel:[18005.036832] sdb: sdb1
2016-02-06T18:19:56.867311-05:00 di=NqJQ6FTJD8 notice kernel:[18005.046685] sd 4:0:0:0: [sdb] Attached SCSI disk
2016-02-06T18:19:59.974505-05:00 di=NqJQ6FTJD8 crit kernel:[18008.072828] ufsd: "mount" (sdb1): is mounted as NTFS (without journal)
From the wdnas.log:
2016-02-06T16:42:50.849510-05:00 di=NqJQ6FTJD8 info logger: INFO: Device ejected: device=3, vendor=Toshiba, model=External USB 3.0, serial_number=2011111316674, revision=0.01
2016-02-06T18:19:52.470809-05:00 di=NqJQ6FTJD8 info logger: INFO: Device added: device=3, vendor=Toshiba, model=External USB 3.0, serial_number=2011111316674, revision=0.01
2016-02-06T18:19:58.892504-05:00 di=NqJQ6FTJD8 info logger: INFO: attached USB partition, reduce inotify limit to: 20000
2016-02-06T18:20:06.355411-05:00 di=NqJQ6FTJD8 info logger: updateShareBindMntDir.sh:--add Toshiba
2016-02-06T18:20:08.528586-05:00 di=NqJQ6FTJD8 info logger: INFO: Partition added: device=3, partition=1, share_name=Toshiba, label=Toshiba, type=ntfs, uuid=5434A73234A71650
