This Techworld document tabulates details of the AIT and VXA tape formats and includes road map details where available. Both formats use 8mm tape and helical scan technology. With this technology data is written in tracks that slant across the tape rather than in tracks that run the length of the tape. The practical effect is that smaller tape cartridges can hold more data than traditional half inch formats such as DLT or LTO.
This is Sony's Advanced Intelligent Tape format. Sony devised it as a follow-on from DDS. A microchip in the catridge, termed a MIC, holds file positioning information resulting in a faster location of files on the tape. There is also a WORM - write once, read many - version of AIT which is beginning to be used for archival purposes. Sony claims that 2.6:1 compression is possible, which is why the compressed capacities are higher than might be expected.
|Raw Transfer Rate||3MB/sec||6MB/sec||12MB/sec||24MB/sec|
|Compressed Transfer Rate||7.8MB/sec||15.6MB/sec||31.2MB/sec||62.4MB/sec|
AIT-3 and 4 capacities could be thought to take AIT into the mid-range market. Two further generations are forecast by Sony: AIT-5 and AIT-6. They are possibly due to appear in 2005 and 2007 respectively. The capacities, transfer rates and availability dates are speculative.
|Raw Transfer Rate||48MB/sec||96MB/sec|
|Compressed Transfer Rate||128MB/sec||256MB/sec|
Sony has developed AIT technology into Super AIT, or SAIT, which uses half inch tape media. It will be covered in a later Techworld feature.
Exabyte's VXA format exists in two generations with a further two coming which, Exabyte says, will double capacity and transfer speed whilst holding price constant. VXA technology has been focused on accurate restoration of data. Data is written to the tape in packets and packets assembled on a read operation with information being taken from multiple read heads. VXA was invented by a spin-off from Exabyte, called Ecrix. When Mammoth sales declined Ecrix and Exabyte joined together and VXA is now the low-end offering with LTO being Exabyte's mid-range format.
|Raw Transfer Rate||3MB/sec||6M/sec||12MB/sec||24MB/sec|
|Compressed Transfer Rate||6MB/sec||12MB/sec||24MB/sec||48MB/sec|
VXA-1 and VXA-2 are current. VXA-3 is set to be announced for a 2004 availability with VXA-4 due for 2006. The capacities and transfer rates and availability dates come from Exabyte.