I can't find explanation on how Windows uses columns in Storage Spaces. I have originally thought it works like this:
I create pool with parity virtual-disk with 3 columns, 3 drives, giving it capacity of 2 drives or 66 percent efficiency.
I add 3 more drives of the same capacity into the pool and extend the virtual-disk, which will again allow me to use additional capacity of the 2 drives I added.
Now I'm getting lost. When I start writing data to this expanded virtual-disk, does it split every write into 2 rows, and every row into 2 columns and then calculates parity for each row? That's what I originally thought, but then Windows asked me to add 2 drives into 3-column parity Storage Space, for a total of 7 drives, which makes no sense to me. What am I missing? How does Storage Spaces write data?