In this article, we will explain why the full capacity of a hard drive on a Zyxel NAS can't indicate the full capacity.
The hard drive capacity appears smaller than claimed by the HDD manufacturer because file systems adopt the binary definition of storage units while HDD manufacturers adopt the decimal definition.
Example: In a 10 TB HDD, one decimal terabyte equals 0.909 binary gigabytes. This is the way the capacity is being used by your operating system.
So, 10 TB X 0.909 = 9.10 TB, this is the disk capacity the NAS system indicates.