Information about Ibm 3850
The IBM 3850 Mass Storage System was an online tape library used to hold large amounts of infrequently accessed data.
The MSS (as it was known) consisted of a library of cylindrical plastic cartridges, two inches wide and four inches long, each holding a spool of tape 770 inches long storing 50MB. These cartridges were held in a hexagonal array of bins in the IBM 3851 Mass Storage Facility. New cartridges were rolled into the facility and were automatically stored in a vacant bin. The data was accessed via one or two IBM 3330 disk drives, the data being transferred automatically between cartridge and disk drive in processes called staging and destaging. These were all connected together with the IBM 3830 Storage Control (also used for disk storage alone), the entire system making up a 3850 unit.
The recording method was unusual for its time. The Tape was wound around a cylindrical mandrel in a helix and stopped. The drive head rotated once (on a rotating drum) to record a diagonal track. Then tape was wound a small step, so the head could iterate over next diagonal track. Depending on technical definitions this might be even considered a first example of a digital helical scan recording, long before Exabyte's helical drive (although analog video helical recording systems were developed earlier).
When free disk space was required a group of cylinders were selected to be destaged to tape, these were transferred with minimal or no change of format. Each tape could store 202 cylinder images each of 19 tracks which corresponded to half of a 3330 disk pack. Cylinder locations on the tape were fixed and identified by markers along the edge.
History
Starting in the late-1960s IBM's lab in Boulder, Colorado began development of a low-cost mass storage system based on magnetic tape cartridges. The tapes would be accessed automatically by a robot (known as an accessor) and fed into a reader/writer unit that could work on several tapes at the same time. Originally the system was going to be used as a directly attached memory device, but as the speed of computers grew in relation to the storage, the product was re-purposed as an automated system that would offload little-used data from hard disk systems. Known internally as Comanche while under development, IBM management found a number of niche uses for the concept, and announced it officially as the IBM 3850 on October 9th, 1974.Description
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Data cartridge
The recording method was unusual for its time. The Tape was wound around a cylindrical mandrel in a helix and stopped. The drive head rotated once (on a rotating drum) to record a diagonal track. Then tape was wound a small step, so the head could iterate over next diagonal track. Depending on technical definitions this might be even considered a first example of a digital helical scan recording, long before Exabyte's helical drive (although analog video helical recording systems were developed earlier).
When free disk space was required a group of cylinders were selected to be destaged to tape, these were transferred with minimal or no change of format. Each tape could store 202 cylinder images each of 19 tracks which corresponded to half of a 3330 disk pack. Cylinder locations on the tape were fixed and identified by markers along the edge.
Models
Several models of the 3851 were available. The smallest A1 holding 706 cartridges storing 35.3GB, while the largest A4 held 4,720 cartridges storing 236GB in a 20-foot long unit. All of the units were also available in the "B models" which added a second controller for on-line backups, as well as offline storage. A second series of 3581s was released on March 6th, 1980, but the entire series was discontinued on August 5, 1986.External links
- Columbia University's MSS
- IBM Archives
- IBM details of tape recording method
- IBM description and announcement
- Good photos of tape cartridge
on-line and off-line have specific meanings with respect to computer technology and telecommunication. The concepts have however been extended from their computing and telecommunication meanings into the area of human interaction and conversation.
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tape library, sometimes called a tape silo, or tape jukebox, is a storage device which contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges and an automated method for loading tapes (a robot).
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City of Boulder
Location in Boulder County and the state of Colorado
Coordinates:
Country
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Location in Boulder County and the state of Colorado
Coordinates:
Country
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Hard disk drive
An IBM hard disk drive with the metal cover removed. The platters are highly reflective.
Date Invented: September 13 1956
Invented By: An IBM team led by Reynold Johnson
Connects to:
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An IBM hard disk drive with the metal cover removed. The platters are highly reflective.
Date Invented: September 13 1956
Invented By: An IBM team led by Reynold Johnson
Connects to:
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A mandrel (pronounced IPA: /ˈmændrɨl/, and also spelled mandril; in American English also called an arbor
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should be added to this article, to conform with Wikipedia's Manual of Style.
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A helix (pl: helices), from the Greek word έλικας/έλιξ
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A helix (pl: helices), from the Greek word έλικας/έλιξ
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Happy", "Cupid" and "Hate You" and Ty Tabor brought "Ocean" to the Tapehead recording sessions. All other songs were band created during the recording session - a song a day for 14 days.
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Helical scan or striping is a method of recording higher bandwidth signals onto magnetic tape than would otherwise be possible at the same tape speed with fixed heads.
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The 8 mm Backup Format is a magnetic tape data storage format used in computer systems, pioneered by Exabyte Corporation. It is also known as Data8. Such systems can backup up to 40 GB of data depending on configuration.
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An analog or analogue signal is any time continuous signal where some time varying feature of the signal is a representation of some other time varying quantity. It differs from a digital signal in that small fluctuations in the signal are meaningful.
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Video (Latin for "I see", first person singular present, indicative of videre, "to see") is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
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U-matic is the name of a videocassette format first shown by Sony in prototype in October 1969, and introduced to the market in September 1971. It was among the first video formats to contain the videotape inside a cassette, as opposed to the various open-reel formats of the time.
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