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{{Short description|Data storage device}}

[[File:Dds tape drive 01.jpg|thumb|300px|[[Digital Data Storage|DDS]] tape drive (bottom). Above, from left to right: DDS-4 tape (20&nbsp;GB), 112m [[Data8]] tape (2.5&nbsp;GB), [[Quarter Inch Cartridge|QIC]] DC-6250 tape (250&nbsp;MB), and a 3.5" [[floppy disk]] (1.44&nbsp;MB).]]

A '''tape drive''' is a [[Computer data storage|data storage device]] that [[digital recording|reads and writes data]] on a [[magnetic tape]]. [[Magnetic-tape data storage]] is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.

A tape drive provides [[sequential access]] storage, unlike a [[hard disk drive]], which provides [[random access|direct access]] storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As a result, tape drives have very large average [[access time]]s. However, tape drives can stream data very quickly off a tape when the required position has been reached. For example, {{As of|2017|lc=on}} [[Linear Tape-Open]] (LTO) supports continuous data transfer rates of up to {{nowrap|360 MB/s}}, a rate comparable to hard disk drives.

== Design ==
[[File:Coloradobrandtapedrive.jpg|thumb|An external [[Quarter-inch cartridge|QIC]] tape drive]]
[[File:DLT7000internal-chtaube040728.jpg|thumb|An internal 5.25-inch full-height [[Digital Linear Tape|DLT]] tape drive.]]
Magnetic-tape drives with capacities of less than one megabyte were first used for data storage on [[mainframe computer]]s in the 1950s. {{As of|2018}}, capacities of 20 terabytes or higher of uncompressed data per cartridge were available.

In early computer systems, magnetic tape served as the main storage medium because although the drives were expensive, the tapes were inexpensive. Some computer systems ran the operating system on tape drives such as [[DECtape]]. DECtape had fixed-size indexed blocks that could be rewritten without disturbing other blocks, so DECtape could be used like a slow disk drive.

Data tape drives may use advanced data integrity techniques such as multilevel forward error correction, shingling, and [[magnetic-tape data storage#Linear|linear serpentine]] layout for writing data to tape.

Tape drives can be connected to a computer with [[SCSI]], [[Fibre Channel]], [[SATA]], [[USB]], [[FireWire]], [[FICON]], or other interfaces.{{efn|Historical interfaces include also [[ESCON]], [[parallel port]], [[Integrated Drive Electronics|IDE]], [[Pertec]].}} Tape drives are used with autoloaders and [[tape libraries]] which automatically load, unload, and store multiple tapes, increasing the volume of data that can be stored without manual intervention.

In the early days of [[home computing]], [[floppy]] and [[hard disk drive]]s were very expensive. Many computers had an interface to store data via an audio [[tape recorder]], typically on [[Compact Cassette#Data recording|Compact Cassettes]]. Simple dedicated tape drives, such as the professional DECtape and the home [[ZX Microdrive]] and [[Rotronics Wafadrive]], were also designed for inexpensive data storage. However, the drop in disk drive prices made such alternatives obsolete.

=== Data compression ===
As some data can be [[Data compression|compressed]] to a smaller size than the original files, it has become commonplace when marketing tape drives to state the capacity with the assumption of a 2:1 compression ratio; thus a tape with a capacity of 80&nbsp;GB would be sold as "80/160". The true storage capacity is also known as the [[native capacity]] or the raw capacity. The compression ratio actually achievable depends on the data being compressed. Some data has little redundancy; large video files, for example, already use compression and cannot be compressed further. A [[database]] with repetitive entries, on the other hand, may allow compression ratios better than 10:1.

=== Technical limitations ===
[[Image:LCM - CDC 606 Tape Transport 01.jpg|thumb|[[Control Data Corporation]] 606 tape drive, showing two long vertical vacuum columns in the lower part.|alt=A large cabinet, about the size of an upright refrigerator, with a glass-covered top part holding two reels of magnetic tape, and a bottom part with control buttons framed by vertical channels.]]
A disadvantageous effect termed '''{{visible anchor|shoe-shining}}''' occurs during read/write if the data transfer rate falls below the minimum threshold at which the tape drive heads were designed to transfer data to or from a continuously running tape. In this situation, the modern fast-running tape drive is unable to stop the tape instantly. Instead, the drive must decelerate and stop the tape, rewind it a short distance, restart it, position back to the point at which streaming stopped and then resume the operation. If the condition repeats, the resulting back-and-forth tape motion resembles that of [[Shoeshiner|shining shoes with a cloth]]. Shoe-shining decreases the attainable data transfer rate, drive and tape life, and tape capacity.

In early tape drives, non-continuous data transfer was normal and unavoidable. Computer processing power and available memory were usually insufficient to provide a constant stream, so tape drives were typically designed for ''start-stop'' operation. Early drives used very large spools, which necessarily had high inertia and did not start and stop moving easily. To provide high start, stop and seek performance, several feet of loose tape was played out and pulled by a suction fan down into two deep open channels on either side of the [[tape transport|tape head and capstans]]. The long thin loops of tape hanging in these ''[[Vacuum column (tape drive)|vacuum columns]]'' had far less inertia than the two reels and could be rapidly started, stopped and repositioned. The large reels would move as required to keep the slack tape in the vacuum columns.

Later, most tape drives of the 1980s introduced the use of an [[buffer (computer science)|internal data buffer]] to somewhat reduce start-stop situations.{{efn|Some modern designs are still developed to operate in a non-linear fashion. IBM's 3xxx formats are designed to keep the tape moving irrespective of the data buffer—segments are written when data is available, but gaps are written when buffers run empty. When the drive detects an idle period, it re-reads the fragmented segments into a buffer and writes them back over the fragmented sections—a 'virtual backhitch'.<ref name=ibm3xxxref1>{{cite web |url=http://news.techworld.com/storage/3238/mainframe-tape-lock-in-ended/ |title=Mainframe tape lock-in ended |last=Mellor |first=Chris |date=2005-03-02 |work=TechWorld |url-status=dead |archive-url=https://web.archive.org/web/20120605022216/http://news.techworld.com/storage/3238/mainframe-tape-lock-in-ended/ |archive-date=2012-06-05}}</ref>}} These drives are often referred to as ''tape streamers''. The tape was stopped only when [[buffer underrun|the buffer contained no data to be written]], or when it was full of data during reading. As faster tape drives became available, despite being buffered, the drives started to suffer from the shoe-shining sequence of stop, rewind, start.

Some newer drives have several speeds and implement algorithms that dynamically match the tape speed level to the computer's data rate. Example speed levels could be 50 percent, 75 percent and 100 percent of full speed. A computer that streams data slower than the lowest speed level (e.g., at 49 percent) will still cause shoe-shining.

== Media ==
{{see also|List of cassette tape and cartridge tape formats}}
[[Magnetic tape]] is commonly housed in a casing such as a [[cassette (format)|cassette]] or [[tape cartridge|cartridge]]—for example, the [[4-track cartridge]] and the [[Compact Cassette (data)|Compact Cassette]]. The cassette contains magnetic tape to provide different audio content using the same player. The outer shell, made of plastic, sometimes with metal plates and parts, permits ease of handling of the fragile tape, making it far more convenient and robust than having spools of exposed tape. Simple analog cassette audio tape recorders were commonly used for data storage and distribution on [[home computer]]s at a time when [[floppy disk]] drives were very expensive. The [[Commodore Datasette]] was a dedicated data version using the same media.

== History ==
{{See also|Magnetic-tape data storage#Chronological list of tape formats}}

{| class="wikitable sortable"
|-
! style="width:5%;"| Year
! style="width:15%;"| {{soft hyphen|Manu|fac|tur|er}}
! style="width:10%;"| Model
! style="width:9%;"| Capacity
! style="width:70%;"| Advancements
|-
|1951
|[[Remington Rand]]
|[[UNISERVO]]
|{{nowrap|224 KB}}<!-- (1200*((1/3.3)/0.0254)*128)/(8*1024) = 223.693629 -->
|First computer tape drive, used {{frac|1|2}}" [[nickel]]-plated [[phosphor bronze]] tape
|-
|1952
|[[IBM]]
|[[IBM 726|726]]
|
|Use of plastic tape ([[cellulose acetate]]);<br />[[7-track tape]] that could store every 6-bit byte plus a parity bit
|-
|1953
|[[IBM]]
|[[IBM 727|727]]
|
|
|-
|1958
|[[IBM]]
|[[IBM 729|729]]{{efn|{{As of|January 2009}}, the [[Computer History Museum]] in Mountain View, California has working IBM 729 tape drives attached to its working [[IBM 1401]] system.<ref>{{cite web|url=http://www.ed-thelen.org/1401Project/1401RestorationPage.html |title=1401Restoration-CHM |date=2011-05-14 |access-date=2012-01-31 |url-status=dead |archive-url=https://web.archive.org/web/20110514135634/http://www.ed-thelen.org/1401Project/1401RestorationPage.html |archive-date=May 14, 2011 }}</ref>}}
|
|Separate read/write heads providing transparent read-after-write verification.<ref>{{cite journal |date=September 1981 |journal=IBM J. Res. Dev. |volume=25 |number=5 |first1=J. P. |last1=Harris |first2=W. B. |last2=Phillips |first3=J. F. |last3=Wells |first4=W. D. |last4=Winger |url=http://www.research.ibm.com/journal/rd/255/ibmrd2505ZD.pdf |access-date=2023-04-19 |language=en |title=Innovations in the Design of Magnetic Tape Subsystems |pages=691–700 |doi=10.1147/rd.255.0691 |archive-url=https://web.archive.org/web/20060909111506/http://www.research.ibm.com/journal/rd/255/ibmrd2505ZD.pdf |archive-date=September 9, 2006 }}</ref>
|-
|1961
|[[IBM]]
|[[IBM 7340|7340]]
|
|10-track 1" tape cartridge that could store every 8-bit byte plus a parity bit.{{efn|Derived from the [[IBM 7950 Harvest#Architecture|IBM 7955]] "TRACTOR" on the [[IBM 7950 Harvest]].}}
|-
|1964
|[[IBM]]
|[[9-track tape#2400 Series|24xx]]
|
|[[9-track tape]] that could store every 8-bit byte plus a parity bit
|-
|1970s
|[[IBM]]
|[[9-track tape#3400 Series|34xx]]
|
|Auto-loading tape reels and drives, avoiding manual tape threading<br />6250 BPI with [[Group coded recording]] (GCR) for error recovery
|-
|1972
| [[3M]]
| [[Quarter Inch Cartridge]] (QIC-11)
| {{nowrap|20 MB}}
| Tape cassette (with two reels)<br />[[Magnetic-tape data storage#Linear|Linear serpentine]] recording<ref>{{cite web|last=Crandall|first=Daryl|title=Another summary of 1/4" tape systems|url=http://www.sunmanagers.org/archives/1990/0087.html|publisher=Sun Managers Mailing List|access-date=2013-04-21|date=April 30, 1990|url-status=dead|archive-url=https://web.archive.org/web/20120310231435/http://www.sunmanagers.org/archives/1990/0087.html|archive-date=March 10, 2012}}</ref>
|-
|1974
|IBM
|[[IBM 3850|3850]]
|
|Tape cartridge (with single reel)<br />First tape library with robotic access<ref name="IBM">{{cite web|url=http://www-03.ibm.com/ibm/history/exhibits/storage/storage_fifty.html |archive-url=https://web.archive.org/web/20050124032735/http://www-03.ibm.com/ibm/history/exhibits/storage/storage_fifty.html |url-status=dead |archive-date=January 24, 2005 |title=IBM Archives: Fifty years of storage innovation |date=23 January 2003 |publisher=03.ibm.com |access-date=2012-01-31}}</ref>
|-
| 1975
| (various)
| [[Kansas City standard]]
|
| Use of [[standard audio cassette]]s
|-
| 1977
| [[Commodore International]]
| [[Commodore Datasette]]
| {{nowrap|1978 KB}}<!-- TurboTape w C90 tape: (3000*90*60)/(8*1024) = 1978 -->
|
|-
|1980
|[[Cipher Data Products|Cipher]]
|(F880?)
|
|RAM buffer to mask start-stop delays<ref>{{cite web|url=http://www.freepatentsonline.com/4500965.html |title=Capstanless magnetic tape drive with electronic equivalent to length of tape - Cipher Data Products, Inc |publisher=Freepatentsonline.com |date=1985-02-19 |access-date=2012-01-31}}</ref><ref>{{cite web|url=http://www.aceware.iinet.net.au/acms/Images/BooksHiRes/000732.jpg |title=Operation and Maintenance Instructions for Model F880 Tape Transport |access-date=2012-01-31 |url-status=dead |archive-url=https://web.archive.org/web/20070922073314/http://www.aceware.iinet.net.au/acms/Images/BooksHiRes/000732.jpg |archive-date=September 22, 2007 }}</ref>
|-
|1984
|IBM
|[[3480]]
|200&nbsp;MB
|Internal takeup reel with automatic tape takeup mechanism.<br />Thin-film [[Giant magnetoresistance|magnetoresistive]] (MR) head<ref>{{cite web|url=http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3480.html |archive-url=https://web.archive.org/web/20050415081621/http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3480.html |url-status=dead |archive-date=April 15, 2005 |title=IBM 3480 magnetic tape subsystem |date=23 January 2003 |publisher=03.ibm.com |access-date=2013-04-19}}</ref>
|-
|1984
|[[Digital Equipment Corporation|DEC]]
|[[Digital Linear Tape|TK50]]
|{{nowrap|94 MB}}
|[[Digital Linear Tape]] (DLT) line of products<ref>{{cite web|url=https://sup.xenya.si/sup/info/digital/MDS/jun99/Cd2/DECSTA/422AAMG1.PDF |title=DECsystem 5100 Maintenance Guide |date=August 1990 |access-date=2012-01-31}}</ref>
|-
|1986
|IBM
|[[3480]]
|{{nowrap|400 MB}}
|Hardware data compression (IDRC algorithm<ref>{{cite web|url=http://www.aldownloading.com/tape-migrating/3480-3490-backup-migrate/3480-3490-migration.htm |title=3480 & 3490 tape backup migration |publisher=advanced downloading ltd |access-date=2013-04-19}}</ref>)
|-
|1987
|[[Exabyte (company)|Exabyte]]/[[Sony]]
|[[Data8|EXB-8200]]
|{{nowrap|2.4 GB}}
|First helical digital tape drive
Elimination of the capstan and pinch-roller system
|-
|1993
|DEC
|[[Digital Linear Tape|Tx87]]
|
|Tape directory (database with first tapemark nr on each serpentine pass)<ref>{{cite web |url=http://alumnus.caltech.edu/~rdv/comp-arch-storage/FAQ-1.5.html |title=Tape |publisher=Alumnus.caltech.edu |access-date=2012-01-31 |archive-date=2011-07-17 |archive-url=https://web.archive.org/web/20110717151910/http://alumnus.caltech.edu/~rdv/comp-arch-storage/FAQ-1.5.html |url-status=dead }}</ref>
|-
|1995
|IBM
|[[IBM Magstar MP 3570|3570]]
|
|Servo tracks - factory-recorded tracks for precise head positioning (Time Based Servoing or TBS)<ref>{{cite web|url=http://www.research.ibm.com/journal/rd/474/biskeborn.html |title=Hard-disk-drive technology flat heads for linear tape recording |access-date=2012-01-31 |url-status=dead |archive-url=https://web.archive.org/web/20080216174000/http://www.research.ibm.com/journal/rd/474/biskeborn.html |archive-date=February 16, 2008 }}</ref><br />Tape on unload rewound to the midpoint—halving access time (requires two-reel cassette)<ref>{{cite web|url=http://maben.homeip.net:8217/static/computers/backup/tsm/links/TSM%20quickfacts.txt |title=Archived copy |access-date=2007-03-19 |url-status=dead |archive-url=https://web.archive.org/web/20071017005349/http://maben.homeip.net:8217/static/computers/backup/tsm/links/TSM%20quickfacts.txt |archive-date=2007-10-17 }}</ref>
|-
|1996
|[[Hewlett-Packard|HP]]
|[[DDS3]]
|{{nowrap|12 GB}}
|[[Partial-response maximum-likelihood]] (PRML) reading method—no fixed thresholds<ref>{{cite web|url=http://www.freepatentsonline.com/6970522.html |title=Data retrieval - Hewlett-Packard Development Company, L.P |publisher=Freepatentsonline.com |access-date=2012-01-31}}</ref>
|-
|1997
|IBM
|[[IBM VTS|VTS]]
|
|Virtual tape—disk cache that emulates tape drive<ref name="IBM"/>
|-
|1999
|Exabyte
|[[Data8|Mammoth-2]]
|{{nowrap|60 GB}}
|Small cloth-covered wheel for cleaning tape heads. Inactive burnishing heads to prep the tape and deflect any debris or excess lubricant. Section of cleaning material at the beginning of each data tape.
|-
|2000
|[[Quantum Corporation|Quantum]]
|[[Super DLT]]
|{{nowrap|110 GB}}
|[[Visual Servoing|Optical servo]] precisely positioning the heads<ref>{{cite web|url=http://findarticles.com/p/articles/mi_m0BRZ/is_12_19/ai_58926467/pg_2 |archive-url=https://archive.today/20120710040635/http://findarticles.com/p/articles/mi_m0BRZ/is_12_19/ai_58926467/pg_2 |url-status=dead |archive-date=2012-07-10 |title=Tape Wars: Is The End Near? - tape drives - Industry Trend or Event - page 2 &#124; Computer Technology Review |publisher=Findarticles.com |access-date=2012-01-31 }}</ref>
|-
|2000
|[[Linear Tape-Open]]
|[[LTO-1]]
|{{nowrap|100 GB}}
|
|-
|2003
|IBM
|[[3592]]
|{{nowrap|300 GB}}
|Virtual backhitch
|-
|2003
|Linear Tape-Open
|[[LTO-2]]
|{{nowrap|200 GB}}
|
|-
|2003
|Sony
|[[Advanced Intelligent Tape|SAIT-1]]
|{{nowrap|500 GB}}
|Single-reel cartridge for helical recording
|-
|2005
|IBM
|[[TS1120]]
|{{nowrap|700 GB}}
|
|-
|2005
|Linear Tape-Open
|[[LTO-3]]
|{{nowrap|400 GB}}
|
|-
|2006
|[[StorageTek]]
|[[StorageTek tape formats|T10000]]
|{{nowrap|500 GB}}
|Multiple head assemblies and servos per drive<ref>{{cite web|url=http://www.thic.org/pdf/July06/sun.rraymond060718.pdf |title=STK Tape Drive Products and Technology |access-date=2012-01-31}}</ref>
|-
|2007
|Linear Tape-Open
|[[LTO-4]]
|{{nowrap|800 GB}}
|
|-
|2008
|IBM
|[[TS1130]]
|{{nowrap|1 TB}}
|[[Encryption]] capability integrated into the drive
|-
|2008
|StorageTek
|[[StorageTek tape formats|T10000B]]
|{{nowrap|1 TB}}
|
|-
|2010
|Linear Tape-Open
|[[LTO-5]]
|{{nowrap|1.5 TB}}
|[[Linear Tape File System]] (LTFS), which allows accessing files on tape in the file system directly (similar to disk filesystems) without an additional tape library database
|-
|2011
|IBM
|[[IBM TS1130|TS1140]]
|{{nowrap|4 TB}}
|Linear Tape File System (LTFS) supported
|-
|2011
|StorageTek
|[[StorageTek tape formats|T10000C]]
|{{nowrap|5 TB}}
|Linear Tape File System (LTFS) supported
|-
|2012
|Linear Tape-Open
|[[LTO-6]]
|{{nowrap|2.5 TB}}
|
|-
|2013
|StorageTek
|[[StorageTek tape formats|T10000D]]
|{{nowrap|8.5 TB}}
|
|-
|2014
|IBM
|[[IBM 3592|TS1150]]
|{{nowrap|10 TB}}
|
|-
|2015
|Linear Tape-Open
|[[LTO-7]]
|{{nowrap|6 TB}}
|
|-
|2017
|IBM
|[[IBM 3592|TS1155]]
|{{nowrap|15 TB}}
|
|-
|2017
|Linear Tape-Open
|[[LTO-8]]
|{{nowrap|12 TB}}
|
|-
|2018
|IBM
|[[IBM 3592|TS1160]]
|{{nowrap|20 TB}}
|
|-
|2021
|Linear Tape-Open
|[[LTO-9]]
|{{nowrap|18 TB}}
|
|-
|2023
|IBM
|[[IBM 3592|TS1170]]
|{{nowrap|50 TB}}
|
|-
|2025
|Linear Tape-Open / IBM
|[[LTO-10]]
|{{nowrap|30 TB}}
|
|}

== Capacity ==
Manufacturers often specify the capacity of tapes using data compression techniques; compressibility varies for different data (commonly 2:1 to 8:1), and the specified capacity may not be attained for some types of real data. {{As of|2014}}, tape drives capable of higher capacity were still being developed.

In 2011, [[Fujifilm]] and [[IBM]] announced that they had been able to record 29.5 billion bits per square inch with magnetic-tape media developed using [[Barium Ferrite]] (BaFe) particles and nanotechnologies, allowing drives with true (uncompressed) tape capacity of 35&nbsp;TB.<ref>{{cite web |url=http://www.fujifilmusa.com/press/news/display_news?newsID=879807 |title=FujiFilm Barium-Ferrite Magnetic Tape Establishes World Record in Data Density: 29.5 Billion Bits per Square Inch |date=January 22, 2010 |publisher=Fujifilm |access-date=2011-07-13 |archive-date=2011-09-29 |archive-url=https://web.archive.org/web/20110929032822/http://www.fujifilmusa.com/press/news/display_news?newsID=879807 |url-status=dead }}</ref><ref name="Harris">{{cite news|url=http://www.zdnet.com/blog/storage/a-70-tb-tape-cartridge-too-much-too-late/769|archive-url=https://archive.today/20130105124237/http://www.zdnet.com/blog/storage/a-70-tb-tape-cartridge-too-much-too-late/769|url-status=dead|archive-date=January 5, 2013|title=A 70&nbsp;TB tape cartridge: too much, too late? |last=Harris|first=Robin|date=January 24, 2010|work=ZDNet|access-date=2011-07-13}}</ref> The technology was not expected to be commercially available for at least a decade.

In 2014, [[Sony]] and [[IBM]] announced that they had been able to record 148 billion bits per square inch with magnetic tape media developed using a new vacuum thin-film forming technology able to form extremely fine crystal particles, allowing true tape capacity of 185&nbsp;TB.<ref>{{cite web |url=http://www.sony.net/SonyInfo/News/Press/201404/14-044E/index.html |title=Sony develops magnetic tape technology with the world's highest*1 areal recording density of 148&nbsp;Gb/in2|publisher=Sony Global |access-date=2014-05-04 }}</ref><ref name="Finags">{{cite news|url=https://www.engadget.com/2014/04/30/sony-185tb-data-tape/|title=Sony's 185TB data tape puts your hard drive to shame |last=Fingas|first=Jon|date=May 4, 2014|publisher=Engadget|access-date=2014-05-04}}</ref>

On December 15, 2020, [[Fujifilm]] and [[IBM]] announced a Strontium Ferrite (SrFe) technology able, in theory, to store 580 TB per tape cartridge.<ref>{{cite web |url=https://www.ibm.com/blogs/research/2020/12/tape-density-record/|title=Hybrid clouds will rely on magnetic tape for decades to come|author=	Mark Lantz|website=[[IBM]] }}</ref>

== Notes ==
{{notelist}}

== References ==
{{Reflist}}

{{Magnetic tape data formats}}
{{Authority control}}

{{DEFAULTSORT:Tape Drive}}
[[Category:Tape-based computer storage|*]]
[[Category:Magnetic devices]]
[[Category:1951 in computing]]
[[Category:1951 in technology]]
[[Category:Computer-related introductions in 1951]]