The RAMAC 305 was the precursor to the IBM 1301 disk storage unit. When released in 1961, the 1301 was the first storage system that used "flying heads" on actuator arms to read and write data to its 50 24-inch magnetic platters. The 1301's head and actuator arm assembly looked something like a bread-slicing machine turned on its side because each drive platter had its own read/write head.
The 1301 had 13 times the capacity of the RAMAC, and its platters rotated at 1,800 rpm -- compared with a spindle speed of 100 rpm for the RAMAC -- allowing heads to access the data more quickly.
"The difference was that the flying heads were able to be closer than the air-bearing heads. You got more tracks and linear density with flying heads ... and the access time was about a tenth the time," Hoagland said. "It had the kind of performance that allowed hard disks to eventually percolate through the whole computer world."
The 1301 reduced the average read head-to-surface distance of from 1,000 micro inches in the RAMAC to 250 micro inches. A micro inch is one-millionth of an inch. To put that into perspective, a human hair is 2,000 micro inches thick. Today's hard drive heads fly about 10 nanometers off the platter, far narrower than line widths used in semiconductor technology.
The success of a disk drive "is derived from a mechanical feature," said Hoagland. "By reducing the [read/write head-to-platter] separation, you're constantly scaling the dimensions for higher densities."
Only two years after creating the 1301, IBM built the first removable hard drive, the 1311. The drive system, which shrunk storage technology from the size of a refrigerator to the size of a washing machine, had six 14-inch platters and contained a removable disk pack that had a maximum capacity of 2.6MB of data. The 1311 remained in use through the mid-1970s.
In 1979, Al Shugart, who had helped develop the RAMAC with IBM, launched Seagate Technology Corp., which became the largest disk drive manufacturer in the world.
Soon thereafter, the innovation floodgates opened. The "small form-factor" hard drive was invented in 1980 by Seagate. That 5-in. ST506 drive held the same capacity as the RAMAC (5MB) and could read or write more than 12 documents at a time in less than a second.
In 1983, the now-defunct company Rodime released the first 3.5-in. hard disk drive that held 10MB of data. Twenty years later, after buying IBM's disk drive division, Western Digital introduced its first 10,000-rpm Serial ATA (SATA) 3.5-in. drive, the Raptor. That drive, created for data center server use, had 37GB of capacity. The following year, in 2004, Toshiba came out with the first microdrive, a 0.85-in. square form factor that could store up to 2GB of data.
Microdrives spurred greater innovation in handheld devices, such as Apple's iconic iPod. When the iPod was first released in 2001, it had a 1.8-in. hard drive with 5GB of capacity. By 2006, the capacity of the iPod microdrive had grown to 160GB.
That was the year that Seagate and Western Digital introduced 2.5-in. hard drives for data center use with 10,000-rpm spindle speeds. Seagate's Savvio 10K.2 stored up to 146GB of data, or about 28,800 times that of the old RAMAC disk system, and was 8,500 times faster. Western Digital's Raptor X held 150GB. With the increased spindle speed, the drives could read or write the complete works of Shakespeare 15 times over in less than a second.
In 2006, Seagate also announced a 1-in. hard drive that held 12GB.
Enter perpendicular technology
More recent leaps in hard drive capacity evolved from the adoption of perpendicular recording methods, which stood the magnetic bits of data upright on a drive platter as opposed to longitudinal recording, which laid them down flat on the platter surface. By standing them up, more data could be crowded into the same space, increasing the areal density of hard drives.
As with all technology, evolution led not only to innovation, but to obsolescence. Remember the floppy disk? Nowadays, hard drives seem to be giving way to solid-state storage, or nonvolatile memory, which is quickly overtaking the market.
Even Hoagland, who has an affinity for hard drives, admits that the hard disk drive is nearing the end of its life for personal use. "The iPad is a good example. It offers [a solid-state drive with a storage capacity] that was adequate 10 years ago for a laptop. Now it's quite adequate because people can do a heck of a lot with that."
"If you want to store every movie ever made in your home, you may buy a hard drive. But typically, if you can get it off the cloud when you want to see it, why would you want it on your disk drive?" Hoagland said. "My next computer won't have a disk drive."
Whither the hard disk?
That doesn't mean disk drives are going away anytime soon. Corporations will continue to expand disk drive farms for years to come just to keep up with the avalanche of data being created every day.
"Every time people create data and put it on the Internet, that means there's a tremendous increase in ... disk farms," Hoagland said. "You can't beat the capacity you can get on a magnetic disk drive, cost wise or volume wise. They're going to be buying disk drives hand over fist indefinitely, because they'll be needed more and more as people find they like using flash memory, but they can't afford to buy a terabyte of flash memory."
Of course, in 50 years, a terabyte of flash memory won't likely be so pricey, if past is prologue.
Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at @lucasmearian, or subscribe to Lucas's RSS feed. His e-mail address is firstname.lastname@example.org.
This story, "Computer History Museum to Highlight Storage" was originally published by Computerworld.