Largest hard-disk platter

The largest platters used in a hard drive were the 48-inch (121-cm) disks mounted in the Librascope Disk File. Only two of these hard drives were ever produced. One was installed at the Stanford University AI Lab in 1967, the other at the University of California's Lawrence Livermore National Laboratory. Each drive included six of these platters, weighed an astonishing 5,200 lbs (2,358 kg) and held 48 MB of data.

Usually such a large disk would create unacceptably slow access times, because of the distance the read-write arm would have to travel. But the Librascope mounted a read/write head on each track. That overcame the problem but made the drive very expensive – $300,000 (around $2.3 million in 2020 dollars). It was also unreliable – after one year a “catastrophic malfunction” eliminated half of its usable capacity. Stanford successfully sued Librascope. This is probably why the product was abandoned by Librascope.

Stanford scrapped the drive in 1975. It donated the controller part to Utah State, which had taken over the Livermore drive, but auctioned the six gigantic platters to staff members as mementos. Four are known to survive. One is on display at Stanford, another is at the Computer History Museum, and a third was made into a coffee table by computer scientist Lester Earnest.