Editing Linear Tape-Open (section)

== Generations ==
As of 2020, nine generations of LTO Ultrium technology have been made available and five more are planned.<ref name="auto1">{{Cite web |title=LTO-9 · New LTO Generation 9 Specifications {{!}} LTO Ultrium |url=https://www.lto.org/lto-9/ |access-date=2022-10-29 |website=Ultrium LTO |language=en-US}}</ref> Between generations, there are strict compatibility rules that describe how and which drives and cartridges can be used together.

{| class="wikitable" style="font-size: smaller;"
|-
! scope="row" | Format
! LTO-1
! LTO-2
! LTO-3
! LTO-4
! LTO-5
! LTO-6
! LTO-7
! ''Type M (M8)''<ref group="Note">Previously unused LTO-7 tape, not an independent generation, part of LTO-8 generation. See: [[#Compatibility|Compatibility]]</ref>
! LTO-8
! LTO-9
|-
! align="left" | Release date
| 2000<ref name="First million">{{cite press release|url=http://www.lto.org/newsite/download/pdf/11_12_01.pdf |archive-url=https://web.archive.org/web/20040306110949/http://www.lto.org/newsite/download/pdf/11_12_01.pdf |url-status=dead |archive-date=March 6, 2004 |publisher=LTO |title=Linear Tape-Open Program Ships One Million Ultrium Tapes in First 12 Months of Availability for market |date=November 5, 2001 }}</ref>
| 2003
| 2005
| 2007
| 2010<ref name="LTO-5" />
| Dec. 2012<ref name="Bechtle" />
| Dec. 2015<ref name="LTO-7" /><ref name="reglto7b" /><ref name="lto7lic" /><!--Specs released September 2015; products expected early 2016-->
| colspan="2" | Dec. 2017
| Sep. 2021<ref>{{cite web |url=https://www.itjungle.com/2021/09/08/lto-9-drives-and-cartridges-finally-get-out-the-door/
|title=LTO-9 Drives and Cartridges Finally Get Out the Door |last=Woodie |first=Alex |date=September 8, 2021 |access-date=September 9, 2002}}</ref>
|-
! align="left" |[[Native capacity]] <small>(uncompressed)</small>
| 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" />
| 6.0&nbsp;TB<ref name="lto7lic" /><ref name="ltogenerations" />
| 9 TB
| 12&nbsp;TB<ref name="Ts2280" />
| 18&nbsp;TB<ref name="lto9rel" /><ref name="ltfs" /><ref name="lto910" />
|-
! align="left" | Advertised capacity <small>([[Data compression|compressed]])</small>
| 200&nbsp;GB
| 400&nbsp;GB
| 800&nbsp;GB
| 1.6&nbsp;TB
| 3.0&nbsp;TB
| 6.25&nbsp;TB
| 15&nbsp;TB
| 22.5&nbsp;TB
| 30&nbsp;TB
| 45&nbsp;TB
|-
! align="left" | Max speed MB/s <small>(uncompressed)</small>
<ref name="ltogenerations" /><ref group="Note">This speed is the data transfer between the drive and the tape. If compression or decompression is being performed, the speed between the drive and the computer writing or reading data could be higher.</ref><ref group="Note">Maximum uncompressed speeds valid for full height drives. Half height drives may not attain the same speed. Check manufacturer's specifications.</ref>
| 20
| 40
| 80
| 120
| 140
| 160
| colspan="2" | 300<ref name="reglto7a" />
| 360
| 400
|-
! align="left" | Time to write a full tape at max speed (hh:mm)
| colspan="3" | 1:23
| 1:51
| 3:10
| 4:20
| 5:33
| 8:20
| 9:16
| 12:30
|-
! align="left" | [[data compression|Compression]] capable?
| colspan="5" | Yes, "2:1"
| colspan="5" | Yes, "2.5:1"
|-
! align="left" | [[Write Once Read Many|WORM]] capable?
| colspan="2" | No
| colspan="5" | Yes
| No
| colspan="2" | Yes
|-
! align="left" | [[Encryption]] capable?
| colspan="3" | No
| colspan="7" | Yes
|-
! align="left" | [[Linear Tape File System|LTFS]] capable?
| colspan="4" | No
| colspan="6" | Yes
|-
! align="left" | Max. number of partitions
| colspan="4" | 1 (no partitioning)
| 2
| colspan="5" | 4
|-
| colspan="12" | <references group="Note" />
|}

[[File:Supertape data storage capacities.svg|thumb|Comparison of "supertape" capacities, including LTO]]

While data capacity and speed figures vary with ''uncompressed or compressed'' data, most manufacturers list compressed capacities and speeds on their marketing material. Capacities are often stated on tapes assuming that data will be compressed at a fixed ratio, commonly 2:1. See [[#Compression|Compression]] below for algorithm descriptions and the table above for LTO's advertised compression ratios.

The units for data capacity and data transfer rates generally follow the "decimal" [[SI prefix]] convention (e.g. mega = 10<sup>6</sup>), not the [[binary prefix|binary interpretation]] of a decimal prefix (e.g. mega = 2<sup>20</sup>).

Minimum and maximum reading and writing speeds are drive-dependent.

Drives usually support variable-speed operation to dynamically match the data rate flow. This nearly eliminates tape backhitching or "shoe-shining", maximizing overall throughput and device/tape life.<ref name="Speed Matching" />

The LTO Consortium provide a roadmap of future generations, which state that LTO-10 is expected to have 36 TB of storage and LTO-14 potentially 576 TB.<ref name="roadmap1120" /><ref name="lto910" /><ref name="lto78" />

=== Compatibility ===
[[file:LTO2-IBM-drive-top-front-qtr.jpg|thumb|An LTO-2 mechanism, from IBM. This [[SCSI]] drive fits in a 5.25 inch, Full-Height [[drive bay]]. ]]
[[file:LTODrive HP-448HH.jpg|thumb|HP Half-Height LTO-2 drive in an enclosure for desktop use]]

In contrast to other tape technologies, an Ultrium cartridge is rigidly defined by a particular generation of LTO technology and cannot be used in any other way (with the exception of LTO-M8, see below). While Ultrium drives are also defined by a particular generation, they are required to have some level of compatibility with older generations of cartridges. The rules for compatibility between generations of drives and cartridges are as follows:

* Up to and including LTO-7, an Ultrium drive ''can read'' data from a cartridge in its own generation and the two prior generations. Later generations reduce read compatibility to only the previous generation: LTO-8 drives can read LTO-7 and LTO-8 tape, but not LTO-6 tape;<ref name="generation-8"/><ref name="Barium Ferrite"/><ref name="ibm-compatibility"/> LTO-9 drives can read and write from LTO-8 and LTO-9 tapes, but not LTO-7 ones. {{Citation |title=LTO Generation Compatibility |date=2024-12-20 |url=https://www.lto.org/lto-generation-compatibility/ |publisher=LTO}}
* An Ultrium drive ''can write'' data to a cartridge in its own generation and to a cartridge from the one prior generation ''in the prior generation's format''.
* Some LTO-8 drives may write previously unused LTO-7 tapes with an increased, uncompressed capacity of 9&nbsp;TB (''Type M (M8)'').<ref name="M8"/> Only new, unused LTO-7 cartridges may be initialized as LTO-7 Type M. Once a cartridge is initialized as Type M it may not be changed back to a 6 TB LTO-7 cartridge. LTO-7 Type M cartridges are only initialized to Type M in an LTO-8 drive. LTO-7 drives are not capable of reading LTO-7 Type M cartridges.<ref name="auto"/>
* An Ultrium drive ''cannot make any use'' of a cartridge from a more recent generation. For example, an LTO-2 cartridge can never be used by an LTO-1 drive; and even though it can be used in an LTO-3 drive, it performs as if it were in an LTO-2 drive.

Within the compatibility rules stated above, drives and cartridges from different vendors are expected to be interchangeable. For example, a tape written on any one vendor's drive should be fully readable on any other vendor's drive that is compatible with that generation of LTO.