If the NAS uses linux RAID you just need drives that are AS LARGE or LARGER than the current drives. Precisely, not what's marked on the box. If you want to b

If the NAS uses linux RAID you just need drives that are AS LARGE or LARGER than the current drives. Precisely, not what's marked on the box. If you want to be on the super safe side and are uncertain, get somebody to help you DD(or dcfldd) each old drive onto a new drive and then just pop the whole new set into the NAS and let it rip. It would also be a good idea to check the NAS vendors forums.