Hi OKLY, some info for you regarding NAS. We do not recommend WD Green because it coz a lot of problem to the NAS. When the NAS not reading, the green will stop spining. But when we wake up the NAS, the green baby a bit lazy to wake up slowly and coz the NAS cannot find the green baby and indicated that this green baby is a bad boy and your NAS will be huha... . So, do your choice carefully.