RN516000 does not recognize newly added WD Black 4TB WD4003FZEX

Hi,

NAS: ReadyNAS 516

Firmware version: 6.4.2

I am having issues with my new RN516000 where it does not increase volume space after addition of a 4th disk. All my disks are 4TB size and in the RN516 compatibility list. I added each disk one at a time and waited in between for several hours until NAS reported free disk space.

I first had two 4TB disks (Seagate) installed. They are as follows:

slot-6: ST4000DM000-1F2168

slot-5: ST4000DM000-1F2168

At this time, I copied about 146 GB of data on to certain shares in the disk and later installed 3rd drive (WD Black) as

slot-4: WDC WD4003FZEX-00Z4S

For the first 3 drives the NAS took a long time for each drive to prepare the system. It kept displaying resyncing on the display for several hours after 3rd drive was installed. Finally, it came back with 7.26 GB of free space. This sounds reasonable as with raidx one disk is used up for redundancy and the remaining two 4TB drives would give me approx. 7.26 GB. 

After this, I installed a fourth 4TB drive (WD Black) as

slot-3: WDC WD4003FZEX-00Z4S

At this time, the NAS simply did not expand the total disk space. It kept is at 7.26 GB. It should have increased the disk space by an additional 3.6 TB. There was no resyncing or did not report any activity. Heard occasional clicks by the drives.

I rebooted several times and let the NAS run overnight. I even moved the newly added 4TB HDD into slot-2 thinking that it would recognize the additional drive. Raidar lists all the 4 disks are "on line" and in good state. The only think I notice is that when I look through the "smart_history" file in the diagnostics log, I see two entries listed as -1. They are for iodec and  cmd_timeouts for the newly added WD Black drives. All other entries are listed as pass or with 0 errors.

Can someone please help me understand the issue and guide me to a fix?

I am thinking of shuffling the drives around. I think that may cause problems from what I read on-line.