Editing Linear Tape-Open (section)

== Core technology ==
=== Tape specifications ===

{| class="wikitable" style="font-size: smaller;"
|-
! scope="row" | Generations
! LTO-1
! LTO-2
! LTO-3
! LTO-4
! LTO-5 <ref name="oracle-lto-5"/>
! LTO-6 <ref name="oracle-lto6"/>
! LTO-7
! LTO-7 Type&nbsp;M (M8) <ref name="auto"/>
! LTO-8 <ref name="StoreEver"/>
! LTO-9
|-
! align=left| [[Native capacity]]
| 100&nbsp;GB
| 200&nbsp;GB
| 400&nbsp;GB
| 800&nbsp;GB
| 1.5&nbsp;TB <ref name="ltfs" />
| 2.5&nbsp;TB<ref name="lto6pressrelease"/><ref name="lto10"/>
| 6.0&nbsp;TB<ref name="lto7lic"/><ref name="ltogenerations"/><ref name=lto10 />
| 9.0&nbsp;TB
| 12&nbsp;TB <ref name="ltogenerations" /><ref name=lto10 />
| 18&nbsp;TB<ref name="lto910"/><ref name="lto78"/><ref name=lto10 /><ref name="lto9rel" />
|-
! Tape length
| colspan=2| 609&nbsp;m
| 680&nbsp;m
| 820&nbsp;m
| colspan=2 | 846&nbsp;m<ref name="lto6-performance"/>
| colspan="3" | 960&nbsp;m
| 1035&nbsp;m<ref name="lto-media"/>
|-
! Tape width
| colspan="10" | 12.650&nbsp;mm ± 0.006&nbsp;mm
|-
! Tape thickness
| colspan=2 | 8.9&nbsp;μm
| 8&nbsp;μm
| 6.6&nbsp;μm
| 6.4&nbsp;μm
| 6.4&nbsp;μm<ref name="oracle-lto6" /> or 6.1&nbsp;μm (BaFe)<ref name="Fujifilm LTO-6"/>
| colspan="3" | 5.6&nbsp;μm
| 5.2&nbsp;μm<ref name="FujiLTO9" />
|-
! Magnetic pigment material<ref>{{cite web | url=https://support.hpe.com/hpesc/public/docDisplay?docId=c04937098&docLocale=en_US | title=Document Display &#124; HPE Support Center }}</ref>
| colspan=5| Metal particulate (MP)
| MP or [[barium ferrite|BaFe]]<ref name="Imation"/>
| colspan="4" | [[Barium ferrite|BaFe]]<ref name="HP-BaFe"/><ref name="FujiLTO9">{{Cite web|url=https://www.fujifilm.com/lv/en/news/hq/6917|title = Fujifilm Launches LTO Ultrium9 Data Cartridge &#124; Fujifilm &#91;Latvia&#93;}}</ref>
|-
! Base material
| colspan="9" | [[Polyethylene naphthalate]] (PEN)
| style="background:lightgrey"|
|-
! Data bands per tape
| colspan="9" |4
| style="background:lightgrey"|
|-
! Wraps per band
| 12
| 16
| 11
| 14
| 20<ref name="ltfs" />
| 34<!-- 2176 tracks, divided by 16 heads and 4 bands -->
| 28<!-- 3585 tracks, divided by 32 heads and 4 bands -->
| 42
| 52
| style="background:lightgrey"|
|-
! Tracks per wrap, read/write elements
| colspan=2| 8
| colspan=4| 16<ref name="ltfs" /><ref name="ibm_lto6_announce" />
| colspan=2| 32<ref name="lto7lic"/>
| 32 ([[Tunnel magnetoresistance|TMR]])
| 32<ref name="FujiLTO9" />
|-
! Total tracks
| 384
| 512
| 704
| 896
| 1,280
| 2,176<ref name="ibm_lto6_announce"/>
| 3,584
| 5,376
| 6,656
| 8,960<ref name="FujiLTO9" />
|-
! Linear density (bits/mm)
| 4,880
| 7,398
| 9,638
| 13,250
| 15,142 <ref name="quantum-ug"/>
| 15,143<ref name="qlto6-ds"/>
| 19,094<ref name="sonylto7"/>
| 19,104
| 20,668
| style="background:lightgrey"|
|-
! Encoding
| [[Run length limited|RLL 1,7]]
| colspan=3 | [[Run Length Limited|RLL 0,13/11]]; [[partial-response maximum-likelihood|PRML]]
| [[Run Length Limited|RLL 32/33]]; [[partial-response maximum-likelihood|PRML]]
| colspan="4" | [[Run Length Limited|RLL 32/33]]; [[Noise-Predictive Maximum-Likelihood (NPML) Detection|NPML]]<ref name="qlto6-ds" />
| style="background:lightgrey"|
|-
! End-to-end passes required to fill tape
| 48
| 64
| 44
| 56
| 80
| 136
| 112
| 168
| 208
| style="background:lightgrey"|
|-
! Expected tape durability, end-to-end passes
| 9,600<ref name="imation-life"/>
| 16,000<ref name="imation-life"/>
| 16,000<ref name="imation-life"/>
| 11,200<ref name="imation-life"/>
| 16,000 <ref name="imation-life"/>
| colspan="4" | 20,000
| style="background:lightgrey"|
|}

=== Physical structure ===
{{Unreferenced section|date=December 2023}}
LTO Ultrium tape is laid out with four wide data bands sandwiched between five narrow servo bands. The tape head assembly, that reads from and writes to the tape, straddles a single data band and the two adjacent servo bands. The tape head has 8, 16, or 32 data read/write head elements and 2 servo read elements. The set of 8, 16, or 32 tracks are read or written in a single, one-way, end-to-end pass that is called a "wrap". The tape head shifts laterally to access the different wraps within each band and also to access the other bands.

Writing to a blank tape starts at band 0, wrap 0, a forward wrap that runs from the beginning of the tape (BOT) to the end of the tape (EOT) and includes a track that runs along one side of the data band. The next wrap written, band 0, wrap 1, is a reverse wrap (EOT to BOT) and includes a track along the other side of the band. Wraps continue in forward and reverse passes, with slight shifts toward the middle of the band on each pass. The tracks written on each pass ''partially overlap'' the tracks written on the previous wrap of the same direction, like [[roof shingle]]s. The back and forth pattern, working from the edges into the middle, conceptually resembles a coiled [[snake|serpent]] and is known as [[Magnetic tape data storage#Linear|linear serpentine]] recording.

When the first data band is filled (they are filled in 3, 1, 0, 2 order across the tape), the head assembly is moved to the second data band and a new set of wraps is written in the same linear serpentine manner. The total number of tracks on the tape is (4 data bands) × (11 to 52 wraps per band) × (8, 16, or 32 tracks per wrap). For example, an LTO-2 tape has 16 wraps per band, and thus requires 64 passes to fill.

=== Logical structure ===

Since LTFS is an open standard, LTFS-formatted tapes are usable by a wide variety of computing systems.

The block structure of the tape is logical so interblock gaps, file marks, tape marks and so forth take only a few bytes each. In LTO-1 and LTO-2, this logical structure has CRC codes and compression added to create blocks of 403,884 bytes. Another chunk of 468 bytes of information (including statistics and information about the drive that wrote the data and when it was written) is then added to create a "dataset". Finally error correction bytes are added to bring the total size of the dataset to 491,520 bytes (480&nbsp;[[kibibyte|KiB]]) before it is written in a specific format across the eight heads. LTO-3 and LTO-4 use a similar format with 1,616,940-byte blocks.<ref name="patent-20090208018"/>

The tape drives use a strong error correction algorithm that makes data recovery possible when lost data is within one track. Also, when data is written to the tape it is verified by reading it back using the read heads that are positioned just "behind" the write heads. This allows the drive to write a second copy of any data that fails the verify without the help of the host system.

=== Positioning times ===

While specifications vary between different drives, a typical LTO-7 drive will take about 15 seconds to load the tape and 20 seconds to unload the tape. These drives have an average rewind time of 60 seconds and an average access time (from beginning of tape) of about 56 seconds.<ref name="ibm_drive_performance_specs"/> Because of serpentine writing methods, rewinding often takes less time than the maximum. If a tape is written to full capacity, there is no rewind time, since the last pass is a reverse pass leaving the head at the beginning of the tape (number of tracks ÷ tracks written per pass is always an even number).

=== Durability ===

LTO tape is designed for 15 to 30 years of archival storage.<ref name="da-11529"/><ref name="sun.com"/> If tapes are archived for longer than 6 months they have to be stored at a temperature between {{convert|16|and|25|C|F}} and between 20 – 50% RH.<ref name="fujifilm-tape-recommendations">{{Cite web|url=https://tapepower.fujifilmrmd.com/Shared/PDF/knowledgebase/LTO_Tech%20&%20C&H_2015.pdf|archive-url=https://web.archive.org/web/20211130062615/https://tapepower.fujifilmrmd.com/Shared/PDF/knowledgebase/LTO_Tech%20%26%20C%26H_2015.pdf|url-status=dead |archive-date=November 30, 2021|title=Fujifilm Tape Care & Handling Recommendations}}</ref><ref>{{Cite web|title=IBM media environmental specifications|website = [[IBM]]|url=https://www.ibm.com/docs/en/ts3500-tape-library?topic=media-environmental-shipping-specifications-lto-tape-cartridges}}</ref>
Both drives and media should be kept free from airborne dust or other contaminants from packing and storage materials, paper dust, cardboard particles, printer toner dust etc.<ref name="fujifilm-tape-recommendations" />

Depending on the generation of LTO technology, a single LTO tape should be able to sustain approximately 200-364 full file passes.<ref name="imation-life" /> There is a large amount of lifespan variability in actual use. One full file pass is equal to writing enough data to fill an entire tape and takes between 44 and 208 end-to-end passes. Regularly writing only 50% capacity of the tape results in half as many end-to-end tape passes for each scheduled backup, and thereby doubles the tape lifespan. LTO uses an automatic verify-after-write technology to immediately check the data as it is being written,<ref name="primer3"/><ref name="NewsBytes_June_2011"/> but some backup systems explicitly perform a completely separate tape reading operation to verify the tape was written correctly. This separate verify operation doubles the number of end-to-end passes for each scheduled backup, and reduces the tape life by half.