So! Since no one actually ever answered this question… For a second time it was asked.
Let me try to re-ignite this topic.
We have established you can upgrade the drives from 2x4TB to higher ones.
Now what? Specifically, once you have the two new higher capacity drives up and running in the device, how do you get all the data from the old drives to the new drives? The old drives are formatted in WD NAS format, so they can’t be read in windows to simply copy everything back over the network. I even tried plugging my old drive in to a USB caddy and using the USB ports in the back of the WD NAS. It recognized the drive, but can’t access the data on it.
Short of putting the old drives back in to the device, and copying everything over the network to another device (Which I don’t have, by the way. At least not with 4TB of free space to just sling around), then put the new drives back in. And copy everything back over to the new drives, SLOWLY over the network again.
Now that I have my new 8TB drives in the NAS working. I want to plug the old 4TB drive in to something, and just copy the data back over to the new 8TB drives in one single swoop, instead of swapping back and forth and copying over the network 4 times.