Now ten years old, Sony's Advanced Intelligent Tape (AIT) format has doubled in capacity every two years, enabling the latest AIT-5 drive to cram 400GB of uncompressed data onto each cartridge. However, performance hasn't kept pace, and Sony could have trouble convincing both new and existing buyers as to the merits of its new technology.

If it wasn't for the badge you'd be hard pressed to tell the AIT-5 apart from earlier models. It takes the same size cartridges, can be had in black or beige and, although a 3.5-inch device, comes ready to fit into a standard 5.25-inch, half-height storage bay.

The bare internal AIT-5 drive we were supplied is mostly sold pre-installed by server vendors, with an end user StorStation bundle also available complete with mounting rails for HP ProLiant servers and a copy of Symantec's Backup Exec for Windows. An external drive is yet another option, with the AIT-5 drive likely to be added to Sony's range of tape automation products later this year.

Offering double the capacity of its AIT-4 predecessor the new drive appears to have a lot going for it, but the Ultra160 SCSI LVD/SE interface is unchanged. That not only limits throughput but also meant having to install a SCSI adapter in the SATA-equipped server we used for our tests. Not a major issue, but a concern in a market where Serial ATA technology now reigns supreme.

We also had concerns when it came to throughput. The 24MB/sec native transfer rate is good, but no faster than the AIT-4 and now out-stripped by other tape formats and cheaper, disk-based backup solutions.

The 2.6:1 compression ratio claimed for Sony's ALDC (Adaptive Lossless data Compression) technology also needs to be taken with a large pinch of salt. If it were to be achieved, it would significantly boost both capacity and throughput, but on our tests we only saw improvements of around 30-40 percent; roughly on a par with other tape and disk compression technologies.

In its favour, the contents of most small business servers will fit onto a single AIT-5 cartridge even without compression. Added to which the new drive can read and write to cartridges designed for use in AIT-3, AIT-3EX and AIT-4 products with WORM (Write Once Read Many) cartridges also available for long term archiving.

We found the new AME III (Advanced Metal Evaporated) tape cartridges online for around £40 plus VAT, working out at a very affordable 10p per gigabyte.

Other than that, however, it's a far from cheap solution that could more than double the cost of a small business server. That's a major consideration when alternative disk-based solutions can match or exceed both the capacity and performance for a lot less.

With double the capacity of its predecessor, the Sony AIT-5 drive will appeal to existing customers looking to keep up with growing backup demands. However, performance is unchanged and the SCSI interface is looking a little old-hat in today's SATA-dominated small business server market.