Demand for networked attached storage (Nas) pushed worldwide disk capacity shipped during the final quarter of 2006 to 1,030 petabytes, new research reports.

IDC's latest Worldwide Disk Storage Systems Quarterly Tracker said that sales of external disk storage systems for the quarter grew $272m, while the total disk storage systems market grew to $6.9bn, up 4.9 per cent from the prior year's fourth quarter.

"The adoption of networked storage continues to fuel the market," said Brad Nisbet, programme manager with IDC's Storage Systems Programme.

"In particular, we saw strong results for Nas which is indicative of ongoing interest in file-related storage.

"In addition, iSCSI continues to emerge as an alternative connection type for many customers as they look to simplify the environment for less mission-critical applications."

EMC maintained its lead in the external disk storage systems market in the fourth quarter with 22.1 per cent revenue share, followed by IBM and HP with 18.6 per cent and 13.7 per cent respectively.

Dell and Hitachi rounded out the top five with 8.1 per cent and 7.3 per cent respectively.

Among the top five suppliers, IBM and EMC posted the strongest year-over-year revenue growth during 4Q06 at 15.5 per cent and 10.0 per cent growth respectively.

The total network disk storage market (Nas Combined with Open San) posted 12.7 per cent year-over-year growth in the fourth quarter to more than $3.3bn.

EMC maintained its leadership in the total network storage market with 28.7 per cent revenue share, followed by IBM and HP with 16.6 per cent and 13.3 per cent respectively.

In the Open San market, which grew 10.5 per cent year over year, EMC led with 25.3 per cent revenue share, followed by IBM with 18.9 per cent.

The Nas market grew 21.9 per cent year over year, led by EMC with 41.2 per cent revenue share and followed by Network Appliance with 24.3 per cent.

The iSCSI San market continued to show strong momentum, posting 78.9 per cent revenue growth compared to the prior year's quarter. Network Appliance led the market with 23 per cent share, followed by EMC with 18.2 per cent.

"The market for network storage systems priced between $15,000 and $149,999 remained a sweet spot for vendors in 2006," said Natalya Yezhkova, research manager with IDC's Storage Systems Programme.

"These products grew at a double-digit rate and outsold the higher-priced segment ($150,000 and over) during all four quarters for the first time.

"Several factors contributed to this dynamic, including the increased adoption of network storage by mid-sized businesses and the growing demand for less expensive, capacity-oriented storage aimed at more non-transactional applications such as digital content, email archives and replicated data."