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LTO (Linear Tape Open) Technology


LTO Drive and Media

LTO stands for Linear Tape Open, and describes a set of standards for drives that may be manufactured by any LTO license holder whereas other drives tended to be proprietary. HP, Seagate and IBM were the drivers behind the format and it has now been adopted by several other drive and media manufacturers including Quantum, Tandberg, Imation, Maxell and Sony.

Initially it was intended to produce two formats of tape under LTO. Ultrium is the one that exists, and LTO has come to mean Ultrium. Ultrium cartridges are a single reel in a case, similar in style to 3480, 3590 and DLT. Apart from being a tried and tested style of cartridge, the physical similarity with other types of tape meant that Ultrium could be adopted by tape library manufacturers with relatively little cost. It could have been a serious drawback to the format if this had not been done, since Quantum were racing Ultrium to market with the Super DLT which was physically identical to the DLT and could have continued the DLT's dominance of the library market.

The other format (that never actually arrived) looked rather like an IBM Magstar 3570 cartridge, the supply and take up reels were within the cartridge and load point was half way along the tape to enable faster access times for near-line storage applications. this is all academic though, Accelis has never been produced.

A new format is always a gamble as there is already a lot of investment tied up in the existing tape formats. there was no means by which Ultrium could come to market as a drive that could also read existing tapes, but the strict adherence to the standard and the development roadmap seemed to give enough confidence in the future of Ultrium for it to be readily adopted.

How LTO Ultrium Works

LTO uses linear/serpentine recording method similar to DLT (as opposed to the helical scan methodology employed by DAT, AIT, Exabyte). The recording media is 1/2" (1.27cm) and housed in a cartridge approximately 4" (10.5cm) square.

serpentine recording

Above: Linear/Serpentine recording

As with many other media types where linear recording is used, data is recorded as a sequence of tracks that run alternately forwards and backwards along the tape. This technique is known as serpentine recording. Unlike with most formats of helical recording drives, by the time the logical end of tape is reached, the media is physically back at the start.

The media is held on a single reel, rather than in a cassette, and the tape is drawn from within the cartridge case and wound around a take-up reel within the drive.

LTO Tape Data Recovery

Ultrium cartridges and drives are well engineered and a lot of effort has been put into avoiding undue wear and tear to the cartridges. The tape load mechanism is quite gentle and the tape guide rollers are chamfered to prevent damage to the edge of the tape. We don't see that many Ultrium tapes for data recovery following physical damage within a drive. They will still, however, wear out if over-used and a failing drive can either damage a tape or produce a faulty recording.

Like all tapes, they are still driven by people and human error is still a force to be reckoned with. Logical problems can also occur, if the data written to the tapes is wrong then it does not matter how well it is physically recorded, data recovery will be needed to get your files back.

LTO Ultrium Type and Capacities

GenerationNative CapacityData Rate (MB/s)YearTape LengthWORMEncryption
Ultrium-1 100GB 40 2000 609m No No
Ultrium-2 200GB 80 2002 609m No No
Ultrium-3 400GB 160 2005 680m Yes No
Ultrium-4 800GB 240 2007 820m Yes Yes
Ultrium-5 1.5TB 280 2010 846m Yes Yes
Ultrium-6 2.5TB 320 2012 846m Yes Yes
Planned Implementations
Ultrium-7 6.0TB 600 2016
Ultrium-8 12.8TB 854

Last Updated (Wednesday, 14 October 2015 15:54)

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