I read somewhere that it's better to leave 1 of 4 bays empty. So instead of 4x2TB =6TB, I could do 3x 3TB=6TB. Then when I need more space it's faster to essentially copy one of the drives to say a 6 or 8TB down the line than it is to just swap and have the raid SHR rebuild the whole volume. Is that a load of bullocks? Does the Disk Station always rebuild the volume from scratch for a day or two? Or is it true it's a lot faster to leave one bay available? I may sell off my old 2TB drives on ebay and stat fresh with 2 or 3 new iron wolfs.