After looking into different technologies including wire matrices and rod arrays, IBM invented the hard disk drive at its San Jose California lab in 1953 and initially referred to the technology as a "Random Access File," which proved to be less expensive and slower than drum memory, but faster and more expensive than tape drives.
The first commercial hard disk drive was shipped in 1956 as the IBM Model 350 disk storage (US Patent 3,503,060) inside the IBM 305 RAMAC system, which offered 5MB of storage at $10,000 per MB. At the time, customers would pay over $3,200 per month for accessing and storing that information as IBM leased its systems. That’s equivalent to over $31,000 per month in 2021. Three generations of RAMAC drives were developed with capacity doubling in each generation.
The IBM 305 RAMAC was comprised of 50 24-inch disk platters contained inside a large boxy cabinet that resembled washing machines -- a far cry from today's 3.5" or 2.5" disk drives, let alone solid state drives which are coming in the even smaller M.2 form factor.