In 1979, IBM introduced the IBM 3370 Direct Access Storage Facility, which was the first hard disk drive available for use with IBM mainframe computers. The 3370 marked a major advancement in data storage technology, offering vastly higher capacity than previous IBM disk drives as well as improved performance.
Background on IBM Hard Disk Drives Prior to 1979
IBM had been manufacturing hard disk drives for use with its mainframe computers since the 1950s. The first disk drive introduced by IBM was the IBM 350 in 1956. The IBM 350 stored 5 million characters (around 5MB) on fifty 24-inch platters. It was the size of two refrigerators and weighed over a ton.
Over the next two decades, IBM continued to enhance its disk drive technology, increasing capacity and performance. Notable IBM hard drives prior to 1979 include:
- IBM 1301 – Introduced in 1961, with over 2 times the capacity of the IBM 350.
- IBM 2321 – Introduced in 1964, the first IBM hard drive with removable data modules.
- IBM 3330 – Introduced in 1970, with a capacity of 100MB.
By the late 1970s, there was increasing demand from IBM mainframe users for higher disk capacity. The IBM 3330, with a maximum capacity of 200MB, was struggling to meet storage needs in many data centers. It was against this background that IBM developed and released the 3370 Direct Access Storage Facility.
Overview of the IBM 3370 Hard Disk
The IBM 3370 Direct Access Storage Facility was first announced on December 3, 1979. Key features and specs of this revolutionary new disk drive included:
- Capacity – The 3370 offered up to 871.1MB of formatted storage, over 4 times more than the previous IBM 3330 drive. It achieved this via a new technology called “thin film heads”.
- Physical Size – Despite offering massively greater capacity, the 3370 had a smaller physical footprint than earlier drives like the 3330. The drive enclosure measured 3.5 feet wide, 2 feet deep and 6 feet high.
- Performance – IBM touted up to a 3-4x improvement in data transfer rates compared to prior drives.
- New Technologies – The 3370 introduced several innovations including servo surface recording, thin film heads, and the use of a dedicated landing zone.
The 3370 was available in two models – the 3370-A and the higher performance 3370-B. The maximum capacity of 871.1MB required the use of twelve 3370-B modules in a single cabinet. Most installations utilized anywhere from 1 to 8 modules.
Initial Reaction to the IBM 3370 Drive
The IBM 3370 generated significant excitement when it was first unveiled to the public. At the time, Computerworld magazine described it as “the most publicized product announcement in IBM’s history” and noted that initial demand was extremely high.
Customers were eager to upgrade from lower capacity IBM drives like the 3330. The improved storage density offered major potential cost savings, since fewer physical drives were needed to house large databases. Users with rapidly growing storage needs finally had a solution.
There were some concerns about the higher cost of the new 3370 technology, which initially carried about a 70% premium over the older 3330 drives. However, most analysts expected rapid adoption based on the obvious benefits.
“It appears this product will be red hot when it hits the streets later this year,” wrote Mitch Kapor, president of a Boston computer consulting company, in 1979.
IBM 3370 Technical Details and Specifications
The IBM 3370 utilized innovative new technologies to achieve dramatic gains in hard disk capacity and performance. Some key technical details and specifications include:
- Recording Method – The 3370 was the first IBM drive to use thin-film head technology. This allowed more tracks to be written in the same disk space.
- Number of Platters – The 3370-A used 8 data platters. The 3370-B used 12 data platters plus 2 dedicated servo platters.
- Data Tracks per Inch – The 3370 increased track density to 1200 tracks per radial inch, up from 800 on the 3330-11 drive.
- Access Time – The average access time was 15 milliseconds on the 3370-A and 12 milliseconds on the 3370-B.
- Data Transfer Rate – The drive had a transfer rate of 1 million bytes per second.
The use of servo tracks and thin-film heads allowed much more precise control of the disk head positioning. This enabled higher track densities without errors. The thin-film heads were produced using advanced semiconductor manufacturing techniques.
The dedicated landing zone helped avoid damage to data tracks during head landing. Previously, the read/write heads would land directly onto the data tracks.
Market Adoption of the IBM 3370 Drive
After its launch, the IBM 3370 quickly gained traction in the market. Initial sales were constrained only by manufacturing capacity, as demand vastly exceeded supply. By the end of 1980, IBM reported that it had shipped over 4,000 drives to customers.
Many organizations were eager to upgrade from the IBM 3330 to gain more disk capacity. The auto industry was an early adopter – Ford Motor Company purchased 3370 drives for database storage in 1980. Insurance companies, banks, and government agencies also rapidly adopted the new drives.
By 1982, IBM had shipped a cumulative total of nearly 15,000 3370 drives. InfoWorld estimated that it accounted for over half of IBM’s multi-billion dollar disk drive business during this period.
The 3370 remained an integral part of IBM’s mainframe storage offering for the next decade. It was eventually replaced by the IBM 3380 Direct Access Storage Device in 1985, which marked another major leap forward in capacity.
Significance and Impact of the IBM 3370
The introduction of the IBM 3370 hard disk drive marked a major milestone in data storage technology. It had a hugely significant impact on IBM mainframe computing in the 1980s.
Some of the key ways the 3370 affected the computer industry include:
- Enabled new applications – The 3370’s vastly larger capacity enabled mainframes to take on data-intensive jobs like transaction processing that were previously not feasible.
- Improved price-performance – Organizations could store far more data at a lower cost per megabyte compared to prior IBM drives.
- Extended mainframe viability – By giving mainframes 10x more storage, the 3370 helped maintain their dominance before the client-server era.
- Set new expectations – Users now expected regular major leaps in hard disk capacity thanks to the precedent set by the 3370.
The 3370 helped ensure IBM’s control over the mainframe storage market in the 1980s and bought time before minicomputers and servers started becoming more viable alternatives. This remarkably successful drive paved the way for even higher capacity with the 3380 just a few years later.
Conclusion
The IBM 3370 Direct Access Storage Facility was a major technological achievement that transformed data storage capabilities for mainframes. Introduced in 1979, it offered up to 871MB of capacity – over 4 times more than prior IBM drives. New technologies like thin-film heads enabled the major increase in storage density.
The 3370 was met with huge enthusiasm and rapidly adopted by organizations that badly needed more disk capacity. It enabled new applications with massive data storage needs, while also extending the viability of mainframes into the 1980s. This pioneering hard disk drive set a new bar for the speed of advancement in data storage, and helped shape expectations that were met by later drives like the IBM 3380.