Disk usage on fresh install

Ok, I shut down my NVX and removed the 4 disk volume and installed a spare 1TB drive. The volume as reported in volume settings is 913GB (about right) and the usage is 46GB (also about right). In the listing it shows the drive as 931GB and 927GB allocated. There is about 24GB used for the overhead to get to 913GB in the volume. This is also what is reported on the front panel. (One reason my OS is taking a little less than yours is that I am on 4.2.20 on this backup unit but my primary is on 4.2.21).

However, RAIDar shows 200MB 0% of 913GB used. Interesting.

However, with the correct volume returned and rebooted, it shows 2537GB of 4620GB used in RAIDar and the volume setting page shows the same. Opening Windows Explorer and pointing to the primary NAS1 I get roughly the same (2.5TB used, 2.0TB available).

I would not worry about it. RAIDar may not account for the OS and only shows the structure. With an empty volume it looks strange, but when you put terabytes of data in the volume, the difference between 204MB and 47GB gets lost in the rounding.