The IBM RAMAC 350, which was part of the IBM 305 vacuum tube computer publicly announced on September 14, 1956.

The IBM 305 RAMAC computer was the first computer to include a disk drive named the IBM 350 Disk File. The 350 Disk File consisted of a stack of fifty 24" discs. The capacity of the entire disk file was 5 million 7-bit characters, which works out to about 4.4 MB in modern parlance.

1956 for the IBM RAMAC computer.

I think about 57 or 58 by IBM in their 305 RAMAC computer. Its 350 disk drive had a capacity of about 5 million characters on a stack of 50 platters 24 inches in diameter it was about 4 feet tall. Worst case track to track access time was 0.8 seconds.

an imb RAMAC weighed 2000 pounds