I've had this My Book Mirror Edition 2 TB for about 6 months. So I decided to Upgrade the 2 1TB Hard drives that where in them. So I went for the Western Digital WD20EARS 2TB Hard Drive SATAII 64MB Cache - OEM Caviar Green. But Every Time I Use Western Digitals WD Drive Manager. It only recognize 1678.03 GB . Then when I change it to Raid 1 it half's it 839.02GB But when i go back to the program it states that I can put it back to Raid 0 at The full 4 TB i Want ....but when I do that it just goes back to 1678.03. Can Any Body Help me with this problem ?