I bought a wdmycloudex4 that came with 4x2tb drives. I made it raid 5 and typically shows 5 tb total. A year or so later, I started getting read/write failures so I figured it was time to swap out the drives. I bought 4x4tb drives and replaced one each week until the all drives were replaced.
However, my NAS still shows 5 tb total. What did I do wrong?