My question is, what NAS USB adapter that one can connect to an external SATA hard drive allows one to view files on the NAS in the local network as well as from outside through the internet?
It needs to allow the hard drive to be mounted on computers such that the drive will transfer files at a faster rate when the computers are in the local network and possibly at a slower rate when they're outside and accessing through the internet. Also cost should be as minimal as possible.
I'm a little confused by this 'NAS USB adapter' you mention, I totally understand why you may be interested in either a SATA-to-USB adapter or a SATA-to-Ethernet/NAS-protocols adapter but I don't know how a USB adapter would form part of a NAS, it's a point-to-point interface not a shared one.
Either way if your question really relates to if there's a difference between a NAS box of any kind that works internally versus one that works externally then I can answer that - there really is no difference. If a device presents itself using NAS protocols (say NFS or CIFS/SMB) then where the client is is irrelevant, it's IP-based so the client could be right next to the device on the same network or across the other side of the planet. What you would care about is what's doing the firewalling and access control, that would be of much more significant concern to me.
For what it's worth, This monolith from LaCie appears to have both USB connectivity AND Ethernet.. So it might do what I want, but possibly not what you want.. Or it might. It's not entirely clear from their website whether it does NAS and DAS type access at the same time.
