A good external hard drive 6 Tera! .... The capacity is huge and you will be hard pressed to fill the hard drive in a very short time! ... Also know that it is not advisable to perform a hard drive to 100 percent of such capacity under penalty of blocking the playhead. for a 6 TB HDD for example fill the 90% is enough.
there 'ability to plug in USB 3.0 and 2.0 (assai fast transfer capability in 3.0)