The state of the art

The current state of the art in magnetic tape storage systems is advancing at a faster rate than it has for several years. Tape is the oldest of the current formats in general terms, and the basic concept of magnetic tape as a digital storage medium has been in widespread use for over fifty years, and for many years a steady increase in the density of data on a tape was achieved by the development of better films and coatings, better magnetic particle manufacture, improved transport mechanics, and improved read/write head engineering.

Helical scanning which writes the data in stripes across the tape provided a leap forward some years ago, but the development of linear scanning technology was actually a little faster, and by 2002 a new generation of linear tape technologies were introduced which re-invigorated the industry and led to renewed competition between vendors to deliver better and better performance.

A combination of moderate data density, but very high surface area per media carrier means that the one terabyte tape cartridge has reached the mass market during 2004.

The development of hard disk technology has been such that in some applications the two approaches have comparable costs. This too has been a spur on development for companies who specialise in tape technology.

The areas where tape is about as good as it can be are in areas like latency- tape has to be fast forwarded or rewound in order to access the data you need. This winding is about as fast as it can be today. Unless radically tougher tape that can stand the stress of dramatically faster winding is developed, access time constraints due to winding will not change.

As tape is a removable media, in a large scale installation a large proportion of the infrastructure can be retained. So long as the tape media storage space can be reconfigured to take the new form factor, and the new read/write devices can be slotted into the bays the old one's fitted, large items like robotics can often be retained with a minimal reconfiguration. Many tape manufacturers therefore attempt to retain some degree of backward compatibility when moving between generations of technology. A large investment in robotics can be a strong incentive for a customer to remain with a supplier.

Indeed, apart from the impact of wear and tear, there are few developments in the field tape library management that are likely to have a dramatic impact on performance in the next decade or so. Robotics systems are already at a very high level of reliability and performance, and though costs for the best systems may slowly fall, there are very few dramatic changes or improvements in this field expected.

Areas for development

However, the rate at which data can be transferred, and the density of storage depend upon two areas of technology that are under constant refinement- head design (left button) and areal density (right button).