Readynas NV+ v2 XRAID2 does not utilise extra capacity on 4TB disks

Hi there,

 

I recently had 2 failed drives in my trusty Readynas NV+ v2 - 5.3.12 firmware - so decided to try my hand with 4tb drives, the only ones supported for the NV+ v2 were the WD Reds (can't remember hardware number off the top of my head, but I got the exact one listed in the compatibility chart.

 

since I had an external backup of the content - I figured I'd factory reset the box and let it recreate the volume again from scratch... this went as planned and I let it create the volume as X-Raid 2, now I had previously used 2 different x-raid calculators and they'd both told me that it would give me approx 7.2tb of storage... however, once completed, I only got 5.4tb (which was basically the same as what I had with the 4x 2tb drives... figuring I had done something wrong, or the previous configuration was still in effect, I took all the drives out, ran a diskpart - clean - on all 4 drives and tried again, with configuration being 2x 4tb drives in channel 1 & 2, with 2x 2tb drives in channel 3 & 4. however, the same outcome resulted from this step as well... a 5.4tb volume clearly showing x-raid.

 

so - are the calculators wrong? or is something else a-foot?

 

what am I missing?

 

Cheers,

Matt