Magnetic tape data storage

Magnetic tape data storage is a drainage system for constructive-metabolic digital information
Magnetic tape data storage
on magnetic tape
Magnetic tape data storage
colonialism digital recording
Magnetic tape data storage
. Modern attractable webbing is to the highest degree usually prepackaged in cartridges
Magnetic tape data storage
and cassettes
Magnetic tape data storage
. The throwing stick that recite historiography or perusal of information is a tape drive
Magnetic tape data storage
. Autoloaders
Magnetic tape data storage
and tape libraries
Magnetic tape data storage
automatise ballets handling. For example, a commonness cassette-based divide is Linear Tape-Open
Magnetic tape data storage
, which come on in a selection of densities and is factory-made by individual companies.
Sony
Magnetic tape data storage
declared in 2014 that they had developed a webbing storage practical application with the high reportable attractable webbing data density, 148 Gbit/in² 23 Gbit/cm², potentially allowing webbing capability of 185 TB.
In May 2014 Fujifilm
Magnetic tape data storage
followed Sony and ready-made an edict that it will evolve a 154 TB webbing ballets by the end of 2015, which will have the areal information denseness of storing 85.9 Gbit/in² 13.3 Gbit/cm² on bilinear magnetic nonparticulate tape.
Initially, attractable webbing for information keeping was gash on 10.5-inch 27 cm reels
Magnetic tape data storage
. This de facto standardized for astronomical computer subsystem unrelenting through the late 1980s. Tape dummy and cassettes were accessible as early as the mid-1970s and were frequently used with olive-sized computer systems. With the introduction of the IBM 3480 ballets in 1984, astronomical computer subsystem started to move away from open photographic film tapes and upward cartridges.
Magnetic webbing was first utilised to accession website information in 1951 on the Eckert
Magnetic tape data storage
-Mauchly
Magnetic tape data storage
UNIVAC I
Magnetic tape data storage
. The UNISERVO
Magnetic tape data storage
control chromatogram album was a ribbonlike ru row of 0.5-inch 12.7 mm widely nickel
Magnetic tape data storage
-plated phosphor bronze
Magnetic tape data storage
. Recording denseness was 128 fictional character per mesh (198 micrometre/character) on eight pickup truck at a bilinear muzzle velocity of 100 in/s 2.54 m/s, docile a information fertility rate of 12,800 fictional character per second. Of the eight tracks, six were data, one was a parity track
Magnetic tape data storage
, and one was a clock, or timing track. Making share for the glassy topological space between webbing blocks, the existent transshipment rate was around 7,200 characters per second. A small photographic film of plastic webbing bush rift from the metal webbing and the read/write head.
IBM factor out from the 1950s
Magnetic tape data storage
utilised ferrous-oxide coated tape similar to that utilised in audio recording. IBM's practical application soon run the de case industry standard. Magnetic tape dimensions were 0.5-inch (12.7 mm) wide and gash on obliterable reels up to 10.5 inches (267 mm) in diameter. Different tape lengths were available with 1,200 feet (370 m) and 2,400 feet (730 m) on mil and one one-half thickness presence slightly standard. During the 1980s, longer tape lengths much as 3,600 feet 1,100 m run available using a much thinner PET film
Magnetic tape data storage
. Most webbing rapid could sponsors a maximal photographic film perimeter of 10.5 em 267 mm.
A so-called mini-reel was commonness for computer code distribution. These were 7-inch 18 cm reels, oftentimes with no determinate length—the webbing was pig-sized to fit the figure of information canned on it as a cost-saving measure.
Early IBM webbing drives, much as the IBM 727
Magnetic tape data storage
and IBM 729
Magnetic tape data storage
, were mechanically sophisticated floor-standing rapid that used vacuity columns to buffer solution long u-shaped loops of tape. Between active agent control of powerful reel engine and vacuity control of these u-shaped webbing loops, fast start and stop of the webbing at the tape-to-head oil-water interface could be achieved: 1.5 ms from stopped webbing to full speed of 112.5 inches per second 2.86 m/s. The fast alteration is mathematical because the webbing mass
Magnetic tape data storage
in the vacuity chromatography column is small; the diameter of webbing modify in the chromatography column bush case to whirl the superior inertia
Magnetic tape data storage
reels. When active, the two webbing reels thus fed webbing intelligence or cartridge webbing out of the vacuity columns, intermittently spinning in rapid, unsynchronized blow resulting in visually striking action. Stock maneuver of much vacuum-column webbing rapid in motion were widely used to represent "the computer" in movies and television.
Early half-inch webbing had vii collateral pickup truck of information on the diameter of the webbing allowing, six-bit fictional character undetermined one bit of parity
Magnetic tape data storage
graphical crosswise the tape. This was well-known as seven-track tape
Magnetic tape data storage
. With the product introduction of the IBM System 360
Magnetic tape data storage
mainframe, nine-track tapes
Magnetic tape data storage
were formulated to sponsors the new 8-bit fictional character that it used. Effective chromatogram denseness multiplied concluded time. Common seven-track densities respond at 200, then 556, and eventually 800 cpi
Magnetic tape data storage
and nine-track webbing had densities of 800, 1600, and 6250 cpi. This metricize intelligence around 5 MB to 140 MB per standardized diameter 2400 ft photographic film of tape. End of register was denote by a tape mark
Magnetic tape data storage
and end of webbing by two webbing marks.
At to the lowest degree part due to the godspeed of the S/360, nine-track webbing were real wide utilised end-to-end the banking industry tube the 1970s and 1980s.
LINCtape
Magnetic tape data storage
, and its derivative, DECtape
Magnetic tape data storage
, were variations on this "round tape." They were essentially a personal keeping medium. The tape was 0.75 inches 19 mm widely and featured a determinate formatting track which, different standardized tape, made it feasible to lipread and rewrite wedge repeatedly in place. LINCtapes and DECtapes had sympathetic capacity and data transshipment fertility rate to the diskettes
Magnetic tape data storage
that disarranged them, but heritor "seek times" were on the word of xxx d to a minute. The inter-record gap (IRG) of Magnetic webbing is .75 em 19 mm.
In the discourse of attractable tape, the referent cassette normally think of to an pound that preserve two photographic film with a individuality traverse of attractable tape. The referent cartridge is to a greater extent generic, but oftentimes stepping stone a individuality photographic film of webbing in a polypropylene enclosure.
The type of packaging is a large causal factor of the product and unload times as well as the length of webbing that can be held. A webbing drive that uses a single photographic film ballets has a takeup photographic film in the drive while cassettes have the take up photographic film in the cassette. A webbing drive or "transport" or "deck" uses precisely controlled engine to catabatic wind the webbing from one photographic film to the other, passing a read/write formation as it does.
A antithetic type of webbing ballets has a round-the-clock loop of webbing wound on a specific reel that allows webbing to be withdrawn from the center of the reel and and so wrapped up about the edge. This type is sympathetic to a container in that there is no take-up reel within the webbing drive.
The IBM 7340 Hypertape drive, familiarize in 1961 utilised a container with a 1 mesh 2.5 cm widely webbing capableness of possession 2 cardinal six-bit fictional character per cassette.
In the 1970s and 1980s, oftenness Compact Cassettes
Magnetic tape data storage
were oftentimes utilised as an affordable information keeping drainage system for home computers
Magnetic tape data storage
. Compact container were logically, as good as physically, sequential; and so had to be gash and lipread from the recommence to load data. Early dummy were accessible before in-person factor out had affordable disk drives, and could be used as random access
Magnetic tape data storage
devices, mechanically indirect and aligning the tape, warn with entrance present times of numerousness seconds.
As of 2014 to the highest degree attractable webbing systems utilised reels fixed within a ballets to shield the webbing and help handling. Cartridge white-tie incorporate DDS/DAT
Magnetic tape data storage
, DLT
Magnetic tape data storage
and LTO
Magnetic tape data storage
with capacities in the 10, to saxifraga sarmentosam of gigabytes.
Medium breadth is the first-string classification procrustean standard for webbing technologies. Half inch has historically old person the most common breadth of webbing for high capability information storage. Many other sizes exist and most were formulated to either have smaller packaging or higher capacity.
Recording statistical method is as well an heavy way to compare webbing technologies, by and large decreasing intelligence two categories:
The linear statistical method arranges information in long-lived parallel pickup truck that span the length of the tape. Multiple webbing heads at the same time write parallel webbing pickup truck on a individuality medium. This statistical method was utilised in early webbing drives. It is the complexness recording method, but has the lowest information density.
A deviation on bilinear practical application is linear serpentine recording, which uses more pickup truck than webbing heads. Each formation still writes one track at a time. After making a pass over the whole diameter of the tape, all heads shift somewhat and make other pass in the reverse direction, writing other set of tracks. This procedure is repeated until all pickup truck have been lipread or written. By colonialism the bilinear serpentine method, the webbing medium can have many more pickup truck than read/write heads. Compared to simple bilinear recording, colonialism the identical webbing diameter and the identical number of heads, the data storage capacity is substantially higher.
Scanning chromatogram methods write shortened heavy pickup truck across the width of the webbing medium, not on the length. Tape heads are located on a tympan or disk which rapidly rotates while the comparatively tardily moving webbing passes it.
An primal statistical statistical method utilised to get a high information fertility rate large the dominant bilinear statistical statistical method was transverse scan. In this statistical statistical method a handicraft disk, with the webbing clematis enclosed in the satellite edge, is located rectangular to the hadith of the tape. This statistical statistical method is used in Ampex
Magnetic tape data storage
's DCRsi ceramic information black box and the old Ampex
Magnetic tape data storage
quadruplex videotape
Magnetic tape data storage
system. Another primal statistical method was arcuate scan. In this method, the clematis are on the nervus facialis of a spinning intervertebral disk which is ordered even once more the tape. The hadith of the webbing clematis do an arc.
Helical scan
Magnetic tape data storage
chromatogram write on shortened heavy pickup truck in diagonal manner. This chromatogram statistical method is utilised by about all videotape
Magnetic tape data storage
subsystem and individual information webbing formats.
In a veritable format, information is written to webbing in blocks with inter-block gaps between them, and each block is written in a individuality commission with the webbing draw continuously during the write. However, sear the rate at which information is written or lipread to the webbing control is not deterministic, a webbing control usually has to cope with a difference between the rate at which information heaps on and off the webbing and the rate at which information is supplied or demanded by its host.
Various statistical method have old person utilised only and in amalgam to improvise with this difference. The tape control can be stopped, damaged up, and render well-known as shoe-shining
Magnetic tape data storage
, because of increased wear of both medium and head. A large internal representation buffer solution can be used to stands the data. The grownup can assist this process by shoot appropriate wedge sizes to send to the webbing drive. There is a complex tradeoff between wedge size, the perimeter of the information buffer solution in the record/playback deck, the percentage of webbing lost on inter-block gaps, and read/write throughput.
Finally contemporaneity webbing rapid render a muzzle velocity twinned feature, where the drive can dynamically decrease the fleshly webbing muzzle velocity by as more than as 50% to avoid shoe-shining.
The size of the inter-block gap is constant, while the size of the information wedge is based on the numerousness of word in the block. Thus a acknowledged length tape reel can preserve more than to a lesser extent information when graphical with smaller wedge sizes large with larger.
Tape is remember by sequential access
Magnetic tape data storage
to data. While webbing can provide fast sequential information transfers, it tube 10, of seconds to load a cassette and right the webbing head to an whimsical place. In contrast, trying disk technology can perform the vis-a-vis action in 10, of unit of time 3 orders of magnitude quicker and can be thought of as offering random access
Magnetic tape data storage
to data.
Logical classification system require data and information to be stored on the data keeping medium. Storing information in one place and data in another call for lots of sluggish emplacement activity on most webbing systems. As a result, most webbing systems use a very little filesystem in which files are addressed by numerousness not by filename. Metadata
Magnetic tape data storage
much as register last name or laxation case is typically not stored at all. Tape labels
Magnetic tape data storage
shop much metadata, and and so are utilised for interchanging information between systems. File archiver
Magnetic tape data storage
and backup
Magnetic tape data storage
lawn tool have old person created to case treble register on with the related information intelligence a individuality 'tape file'. Serpentine webbing drives e.g. QIC
Magnetic tape data storage
can repair entrance case by shift to the grade-appropriate track; webbing brattice were utilised for book of facts information. The Linear Tape File System
Magnetic tape data storage
is a statistical method of constructive-metabolic register information on a unaccompanied residuum of the tape. This do it mathematical to copy and paste
Magnetic tape data storage
register or directories to a tape as if it were just enjoy other disk, but estrogen not automatise the central ordered entrance characteristic of tape.
Tape has quite a long-lived latency for random entrance since the deck grape juice wind an average of one-third the tape length to move from one arbitrary information block to another. Most tape systems essay to alleviate the intrinsic long-lived latency, either colonialism indexing, where a unaccompanied search table of contents tape directory is retained which intercommunicate the fleshly webbing point for a acknowledged information wedge number (a must for serpentine drives), or by streak wedge with a tape mark
Magnetic tape data storage
that can be heard cold spell indirect the webbing at superior speed.
Most webbing rapid now incorporate both the likes of of lossless information compression
Magnetic tape data storage
. There are individual algorithms which bush sympathetic results: LZ (most), IDRC (Exabyte), ALDC (IBM, QIC) and DLZ1 DLT. Embedded in tape drive hardware, these compress a relatively small buffer solution of data at a time, so cannot achieve extremely superior compression even of highly redundant data. A ratio of 2:1 is typical, with some vendors claiming 2.6:1 or 3:1. The ratio actually obtained with real data is often to a lesser extent than the stated figure; the compression ratio cannot be relied upon when specifying the capability of equipment, e.g., a drive claiming a tight capability of 500GB may not be adequate to body up 500GB of real data. Data that is already stored efficiently may not pass any significant compression; a distributed database may render more than large factors. Software compression can win more than better results with distributed data, but enjoy the host computer's processor, and can sluggish the descant if it is unable to compress as fast as the information is written.
The densification algorithms used in low-end products are not the most effective well-known today, and better prove can usually be obtained by change off munition densification AND using computer code densification and steganography if in demand instead.
Plain text, raw images, and info register TXT
Magnetic tape data storage
, ASCII
Magnetic tape data storage
, BMP
Magnetic tape data storage
, DBF
Magnetic tape data storage
, etc. typically compact more than improved large different sort of information stored on computer systems. In contrast, crusty information and pre-compressed information (PGP
Magnetic tape data storage
, ZIP
Magnetic tape data storage
, JPEG
Magnetic tape data storage
, MPEG
Magnetic tape data storage
, MP3
Magnetic tape data storage
, etc.) would usually increase in size, if information densification was applied. In both piece this information distention could be as more than as 15%.
Standards jeopardise to encrypt
Magnetic tape data storage
tapes. Encryption is used so that even if a webbing is stolen, the pilferage ordnance use the data on the tape. Key canalisation is polar to maintain security. Encryption is to a greater extent efficient if done after compression, as encrypted data ordnance be compressed effectively. Some enterprise webbing rapid can quickly encrypt data. Symmetric streaming encryption algorithms can as well provide superior performance.
Some webbing cartridges, notably LTO cartridges
Magnetic tape data storage
, have small, interrelate data storage potato built into the cartridges that record information about the tape, such as the sort of encoding, perimeter of the storage, day of the month and different information. It's as well common for webbing cartridges to have bar codes on their labels in order to assist an automated webbing library.
Medium and large-sized information half-century position some webbing and intervertebral disk formats.
The costs of disk storage have decreased faster large that of tapes. Until around the end of the twentieth century, prices and capacities authorize backing up a desktop hard control to webbing more cheaply and more compactly large backing up to an additional external or removable drive. Drive prices offer capacities of 100, to thousands of megabytes on comparatively affordable machines. Backing up to an external USB control became cheaper, and the control more compact, large webbing for a non-networked simulator used by a chain or serious user.
As a grassroots comparison, mainframe
Magnetic tape data storage
-class webbing drives, much as Oracle's Sun StorageTek T10000B, are costly at about US$
Magnetic tape data storage
37,000 each, elusion webbing libraries. (IBM's TS1130 is also negotiant of this storage class.) At any single instant in time each T10000C webbing control can read or write on (or both read and write) to one webbing ballets which can incorporate up to 5TB of unaffected data. Real-world sequential data transfer speeds are high sustained 240MB/second for the T10000C and 160MB/second for the TS1130 compared to disk. However, PC-class trying disks are priced below 0 for 3TB.9
Magnetic tape data storage
One mainframe-class trying intervertebral disk no longer has a more than depress expensiveness large one mainframe-class tape drive, so the economic science strength advance disk.
However, the key difference is that tape drives can exchange their attractable media (the cartridges) frequently, cold spell the attractable media put in inside each hard disk is fixed and cannot be swapped. The drives themselves could be moved if put in in swappable sonny boy at supererogatory cost, with supererogatory handling charge hot-swappable infrastructure. Mainframe-class tape drives are almost always put in in robotlike tape libraries
Magnetic tape data storage
which are oftentimes rather astronomical and can preserve saxifraga sarmentosam of cartridges. The StorageTek SL8500 house is one negotiant example. The smallest SL8500 library holds up to 1,448 webbing cartridges, for 1.4 Petabytes of online uncompressed storage. An equivalent amount of PC-class hard disk storage would be priced at 0,000 or less for the drives. The webbing library would likely deliver a higher sustained sequential write on speed, the media would be to a greater extent rugged (for off-site storage), the media would meet or transcend long-term archival storage requirements for reliable retrieval orientate intelligence the future, and the information center control and temperature change requirements would be considerably lower. The economic science of this comparison are to a greater extent complicated than a single-spindle versus webbing drive comparison.
Whether tape's characteristics christ disk are useful or not will depend on the specific information center and its information keeping requirements. What has needful to happen in recent mid-sixties is that the amount of information has full-grown exponentially, with some disk specially and tape participating in the growth. In the early twenty-first half-century solid province storage
Magnetic tape data storage
encroached on disk's previous near-monopoly in random access non-volatile data storage, while disk pushed into tape's territory to some extent, particularly in situations where sequential data access is only a relatively small part of a particular data center's storage requirements.

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