Network Instruments has brought out an expandable version of its GigaStor network data recorder, capable of storing up to 48 terabytes of network traffic.

The company said the device needs that high capacity because of the regulatory pressure on its customers to document their network transactions over longer times - and of course the ever-increasing speed of networks. The box starts at £46,800 for 16TB and is then expandable in 16TB increments. A version which can capture 10Gig full-duplex Ethernet at line speed lists from £64,800.

"Using a Sky Plus-like device on your network to record all traffic for retrospective analysis has shifted from an emerging technology to being the primary way many organisations troubleshoot network problems," said Douglas Smith, NI's co-founder and president. "With up to 48TB, GigaStor Expandable can record more than any other solution."

Of course, at 20Gbit/s for full-duplex, a 10Gig connection at 100 percent load could fill 48TB in about five hours, once you allow for the overhead that GigaStor adds by indexing the stored packets for faster retrieval.

However, most won't actually be fully loaded or 10Gig full-duplex, said NI's European sales director, Ian Cummins.

"I've only a couple of times had people do the sums and say 'Oh, that's only a few hours'," he added.

Previous versions of GigaStor have included the ability to store network traffic to a SAN, so why build so much disk into the device itself? It's down to the performance needed, according to Cummins.

"You would need a dedicated SAN for this because we would be streaming data consistently and at high speed," he said. "You could offload the packets to other storage, if you have a way to move this vast quantity of data.

"Normally though, people keep this as a rolling window, for example storing traffic for seven days and if there's no problem notified by then, they let it roll over."