Magnetic tape

A magnetic tape is a data storage medium. It is usually made of a long, narrow sheet of plastic that is coated with a magnetizable material. The tape is wound on winding cores ( Bobby ) or coils are frequently used in cassettes.

3.1 tape
3.2 videotape
3.3 disk in Information Technology 3.3.1 List of disk types in Information Technology
3.3.2 benefits
3.3.3 disadvantages

History

The granddaddy of the magnetic tape technology is the 1898 invented magnetic recording on wire. In this invention, sound recordings were stored on a thin steel wire. The recording and playback speed was 610 millimeters per second. For the usual capacity of one hour, the wire was 2195 feet long and was due to its small thickness on spools of a few centimeters in diameter space. This technology has been superseded with the appearance of commercial magnetic tape recorders quickly. However, found wire recording devices until well into the 1970s in satellites and other unmanned spacecraft use.

First magnetic tapes have already been introduced in the 1930s in the United States. In Germany, AEG developed and I.G. Colors of the necessary technology from 1935, which was then used in the 1940s to record analog audio signals. First they were made of coated paper or of homogeneous magnetizable material. The present magnetic tape is a development of AEG and IG Colors ( BASF) in 1935 to 1940. Later they were also the basis of magnetic video recordings ( Mavicord, MAZ - band). Then served as media of electronic data processing in addition to drum store in the mainframe computers of the 1950s and 1960s. Magnetic tapes are available in many formats and they still serve the preservation of digital video, audio and digital information generally for electronic data processing. The precursor of magnetic tapes were in the analog sound the record and the Edison roller in data technology punched tape and punched cards. In addition to mechanical and magnetic plates ferromagnetic wires were used in the data processing technology. Digital Magnetic Wire devices ran up to the 1960s, plates even longer. Magnetic tapes offered due to the large available for storing surface but much higher data densities and write and read speeds than the older technologies. Due to the disadvantages that arise from the only sequential access to the data on a magnetic tape, they were nevertheless initially by drum storage or magnetic disks and now also propagated by hard drives, enable random access to data, at least partially detached.

Currently the use of magnetic tapes is declining, in audio CDs and semiconductor-based MP3 players dominate the scene. In video and multimedia especially optical data storage and semiconductor-based to a lesser extent the media are used. In the data processing technology, especially in the private sector, dominated by a combination of the above-cited media, additionally semiconductor -based USB flash drives and external hard drives (USB, FireWire, eSATA) displace the tape technology. Currently, magnetic tapes are also now widely used for professional backup and archiving especially large data archives. However, disk-based systems capture now in this area in the form of virtual tape libraries their market shares.

View

Originally, magnetic tapes an enormous advantage: they could accommodate many square centimeters data storage in the smallest volume. This advantage was purchased by the sequential access method impractical. This advantage today attacks barely, because current hard drives today use far more sophisticated recording techniques (eg perpendicular recording ) as bands and achieve extremely high densities writing. Consequently disks can already today, even without the drawbacks of the sequential access method, a higher storage capacity (per volume) achieve as magnetic tapes. The same applies also for current semiconductor-based and optical storage. If magnetic tapes can not follow suit here, it is expected that they will lose market share.

In the area of large data archives magnetic tape systems today have two advantages over disk systems: With modern robots and magnetic tapes succeeds in significantly larger amounts of data to be accommodated in a server cabinet than disk storage, so that less space is required. In addition to magnetic tapes - as opposed to hard drives - are not permanently kept in motion; they are therefore more energy efficient, generate less heat and are less sensitive to vibration and other mechanical influences. In this respect have magnetic tapes - especially for long-term storage of infrequently used data - continues to be a privilege and market relevance.

Technology

The resolution of the magnetic ribbons is dependent on the sensitivity of the magnetic layer, the width of the strip and its playback speed. Accordingly, over time, very different formats and steel grades were developed. In the 1980s complicated coatings were possible. Instead oxides höchstkoerzitive pure metal layers were applied. Modern video recording tapes in Betacam SP to HD SR tape are highly sensitive media for the modern high-resolution HD TV Television:

35 mm, 17.5 mm, 16 mm, 8 mm perforated magnetic film strip ( two lane film SEPMAG )
Magnetic edge track on film strips ( so-called einstreifiger film COMMAG )

Almost all formats have been used for the digital recording of computer data (from the 2-inch coil to Datasette ).

To make unsupported tape winding operation safer, the back of the tape may be coated. Already a thin Rückseitenmattierung improved winding performance.

Meanwhile, the magnetic tapes have largely been replaced for many applications by other data store. Direct successors were hard drives and optical data storage, such as compact discs.

Applications

Tape

For analog recording and reproduction of audio signals with audio recorders were widely used earlier ( pre-1970 ) tapes with coils and later (after 1970) cassette recorder with compact cassettes. For professional users, such as radio transmitters, cantilevered ribbon winding on Bobby's were common. In the office everyday, primarily in dictation, but also in answering machines microcassette were used. Magnetic tape -based equipment for digital audio recording or playback, however, never had a large spread, they could not prevail against CDs and especially against rewritable CDs. With the proliferation of formats and MP3 players can also be found in the audio field semiconductor-based memory becoming increasingly widespread.

Analogue magnetic tape formats for audio recording:

Tape (from 1935) ( reel tape recorder )
Fidelipac cassette ( 1956 )
4-track cassette stereo (from 1962)
Compact Cassette ( 1963, stereo from 1967) ( cassette recorder, Walkman )
DC International ( from 1965)
8-track cassette stereo (from 1965)
Mini Cassette ( Dictaphone)
Micro-cassette (from 1969) ( answering machine, voice recorder )

Digital tape formats for audio recording

Digital Audio Tape ( 1983 ) ( DAT drive )
DCC ( from 1992)
DTRS (from 1993)
ADAT (from 1993)

Cantilever tape winding on a Bobby

Audio cassettes

Digital Audio Tape

Videotape

Record and play back video recordings or films ( picture and sound recording ) to tape cassettes come almost exclusively used. The magnetic recording can be done (short deck ) either classic analog or digital. There are different standards, data formats and cassette sizes that have been optimized for use in various devices. For example, were very often used VCR on VHS base in the private sector for analog recording and playback of movies. For professional use high-quality systems such as Betacam were developed. More modern systems use digital video cassette, for example, by DV and miniDV standard, both are very compact formats and are optimized for recording using the camcorder. Due to the advent of DVD - Video, rewritable DVDs and hard disk recorders and digital storage and the importance of video cassettes has declined drastically - many video stores have now converted from VHS tapes to DVDs.

U-matic cassette

VHS

Digital video tapes: DVCAM -L, DVCPRO -M, MiniDV

Analogue magnetic tape formats for video recording:

Quadruplex: 2 -inch MAZ quad format on coil ( 1956 ) from 1958 in color
1 inch C 1 -inch VTR EV format on coil ( 1964)
U-matic (1968 )
VCR system (1971)
Betamax (1976 )
VHS (1976 )
Video 2000 (1979)
Betacam (1982)
VHS-C (1983)
Video 8 (1985)
Super Beta ( 1985)
S-VHS ( 1987)
Hi8 (1989 )

Digital tape formats for video recording:

D1 ( 1986)
D2
Digital Betacam (1993 )
DV ( 1994)
MiniDV (1995 )
D -VHS (1998)
Digital8 ( 1999) ( DV Hi8 tapes )
HDCAM (1999)
M2

1/2 " magnetic tape technology from the 1950s and 1960s

Computer magnetic tape 6250 CPI ( around 1985 )

QIC - DC600A - magnetic tape cassette technology from the 1970s and 1980s

DDS-2 tape cartridge technology developed in the late 1980s

LTO Ultrium tape cartridge technology developed in the late 1990s

Disk in Information Technology

Magnetic tapes were formerly a general technique widely used for data storage. For various reasons (cost, cumbersome handling, lack of robustness - especially with cheap systems ) they are today, and if at all only used in private and SoHo area only rarely for data backup and archiving. Instead, there are now mainly recordable CDs and DVDs, and various USB devices or external hard disks are used.

In the professional environment, magnetic tapes are often due to their generally high reliability and long term stability even today to (batch) data processing and data storage and archiving as before, mostly in tape libraries ( with some thousands of bands ), are used. Professional hard disk subsystems (SAN, SAS) offer no better cost factor and will therefore only be used as a substitute for bands occasionally. The PC area in frequent (re ) writable CDs and DVDs, and various USB media or inexpensive external PC hard drives can play virtually no cost advantage in the professional field, because they apply here too unreliable as far.

List of media types in Information Technology

ADR (from 1999 ): ADR -30, ADR 50, ADR 2.60, ADR - 2120
AIT (from 1996): AIT - 1 to AIT -5
DAT ( 1989 ): DDS1 to DDS4
DLT (from 1984 ): Tape I to IV tape, SuperDLT
Floppy Tape ( 1989 ): QIC -40, QIC -80
IBM 7 track 1/2 " (from 1952): 726-729, 7330 and 24xx -7- track
IBM 9-track (from 1964): 24xx - 9-track, 3480, 3490
IBM Magstar (from 1996): 3570, 3580, 3590
IBM Jaguar ( from 2003): 3592, TS1120, TS1130, TS1140
Kansas City Standard ( 1975) and Datasette (1977 ): Compact Cassette
LTO (from 2000): Ultrium 1, Ultrium 2, Ultrium 3, Ultrium 4, Ultrium 5, Ultrium 6
Mammoth ( 1994 ): M- 1, M- 2
QIC (from 1972): DC600, DC2120, DC6150, DC6525, DC9100, DC9120
SLR ( as of 1986 ): SLR1 to SLR5
StorageTek Redwood (from 1995): SD -3 ( Redwood )
StorageTek T- 9xxx series ( from 1996): T9840a to T9840D, T9940a, T9940B
StorageTek T- 10xxx series ( from 2006): T10000, T10000B
Sony Super AIT ( SAIT ) ( from 2003): SAIT SAIT - 1 to 4
Travan ( as of 1985): TR- 1 to TR -7
Exabyte VXA (from 1999 ): VXA VXA- 1 to 4

Benefits

High capacity ( currently more than 6,000 GB per tape )
High sequential write rate ( currently up to 280 MB / s per drive)
Guarantees a long shelf life (some over 30 years)
Outsourced
Re-recordable/erasable
Comparatively inexpensive media - but not cheaper than eg USB hard disk in the PC sector
Media are resistant to impact and falling
Tape libraries (including ribbon robot or tape libraries ) available with hundreds of thousands of drives and media (eg Quantum Scalar 10K)

Disadvantages

Sensitivity, for example against dust, moisture, temperature or magnetic fields
Wear, replacement necessary after repeated use
Appearing data can be added only at the end
If data is to slowly supplied to the drive, the capacity of some media types can not be used to 100 %. See also Shoeshine problem

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