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IBM 3380 direct access storage device

IBM 3380 Direct Access Storage Device

IBM 3380 Direct Access Storage Device
IBM 3380 Direct Access Storage Device

When the IBM 3380 Direct Access Storage Device (DASD) was rolled out in June 1980, it gave customers the ability to store up to 2.52 billion characters of information, almost four times the amount of previous IBM storage devices. For users that needed rapid access to large amounts of stored information, the 3380 transferred data at three million characters a second, more than twice the rate of the IBM 3350. Design innovations improved the average time to locate information from 25 to 16 thousandths of a second. New film head technology allowed data to be read and written at three million characters a second -- two and a half times the previous rate.

New Technology

The new film head technology combined with a more compact design enabled IBM engineers to reduce power consumption on the 3380 by up to 70 percent, floor space by up to 65 percent and heat generation by up to 75 percent when compared to equivalent storage in IBM 3350 DASDs. Read and write heads, disks and two actuators were integrated into two head/disk assemblies to improve reliability and efficiency.

Dynamic path selection, an optional internal architectural function of the 3380, provided a second data path for attachment of the 3380 to a second storage director which controlled the transfer of data. This alternate path provided concurrent access to data and could improve availability if access was lost through malfunction of a channel, storage director or controller.


The 3380 used "count-key-data" architecture to facilitate migration from IBM 3350 and 3340 DASDs. The 3380 could attach to IBM 3031, 3032 and 3033 processors and 3042 Model 2 attached processors through a Data Streaming feature to permit the use of a data rate of three million characters per second. With an optional Speed Matching Buffer feature, the 3380 devices could be used at the 1.5 million characters per second data rate of the IBM 3031, 3032 and 3033 processors, 3042 Model 2 attached processors and the IBM System/370 Models 158 , 158-3, 168 and 168-3.

To meet the need for growth, a "string" or group of four 3380s could store more than 10 billion characters of information, and each storage director could control up to two strings of four 3380s.

The IBM 3380 was initially available in six models, four of which included control functions, and three of which included fixed head technology.

Depending on the features selected, purchase prices at announcement for the 3380 Model A DASDs ranged from $97,650 to $142,200. Lease charges ranged from $2,170 to $3,713 a month. Model B devices could be purchased for $81,000 or $111,600, or leased for $1,800 or $2,480 a month.

First customer shipments for all 3380 models were initially scheduled to begin in the first quarter of 1981. In March of that year, however, IBM reported that initial deliveries would be delayed because of a technical problem identified during product testing prior to customer shipment. Six months later, the problem was corrected and the 3380 was operating in IBM laboratories and customer test locations with outstanding performance and excellent overall reliability. The first customer shipment of a 3380 from the IBM General Products Division plant in San Jose, Calif., took place on October 16, 1981.

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