there is only one 3.5" hdd that has 1tb storage which is the hitachi^^^^^ there are only two companies that make hdd's larger then 500gb!!! What you have seen in an external solution is a 2x500gb in raid0 configuration this makes both drives work in unison with the data striped between them it is cheaper to buy 2x500gb then one hitachi and the performance is better. I have 1.32tb in my computer and 6.75tb in my server