Battle of the technologies
There are a wide variety of different tape formats available, offering different storage capacities, data speeds and other features.
Broadly, the field can be split into two dominant tape recording technologies: helical scan and linear scan. There are staunch supporters of both technologies but the basic pros and cons are outlined below.
Amongst the linear-tape technologies there is quite a battle between LTO and DLT (including its sibling SuperDLT). Although there are technical merits to both technologies, the large back catalogue of DLT tapes in the archives of many organisations still gives SuperDLT an advantage over LTO because of its backward compatibility with DLT.
Helical scan tape (AIT, VXA, DAT 4 & 8mm)
A helical scan drive operates similarly to a VCR. A rotating tape head lies at an angle to the tape and leaves diagonal strips of data.
The drives have a relatively complex design, with many more motors and contact points than LT, and there are long tape paths because the tape is pulled from the cartridge around tension devices, guide pins, and rollers.
All this enables the format to store a high bit density on media. In theory, this format is less affected by print through and tape stretch than LT.
Linear tape (DLT, SLR, Travan, Accelis, Ultrium)
A linear tape is closer to an audio cassette recorder in operation. The tape simply runs past the tape head in a straight line.
Supporters claim LT was designed for data storage because the tape never leaves cartridge and is only touched by the recording head resulting in a simple design with few moving parts and a short tape path.
Compared to helical scan, linear offers a relatively low bit density over a larger media area. In theory, this format is more affected by print though and tape stretch than the diagonally encoded helical scan.
