the biggest hard drive in the world ...

 

5MB. (yes, that's MegaByte)

in 1956.
In September 1956 IBM launched the 305 RAMAC, the first computer with a hard disk drive (HDD). The HDD weighed over a ton and stored 5MB of data.

Appreciating your USB memory stick a little more now? ;)

thanks Noorie for the heads up.

ps.  People look at me strangely when I tell them that the first PC I used (a Wang) had RAM made up of an array of magnetic cores with fine wires running though them to polarise them and took up more space than most tower casings these days.

I also used punched cards on the UCT mainframe to learn FORTRAN.  Never had to be subjected to COBOL thankfully! ;)