Research house IDC reckons the disk storage market will experience a 6.7 per cent slowdown in spending this year compared to 2008, but growth will resume at a pedestrian 1.5 per cent next year.

A lot of this year's decline is due to lower server sales, with a consequent fall in direct-attached storage sales. However, total external disk storage systems end-users' sales will also fall 3.1 per cent this year, IDC says.

On the capacity front there will be growth, but at a slower clip than the 50-60 per cent annual growth we have become used to. Overall disk storage capacity will grow 35 per cent this year compared to 2008, but external disk storage capacity, which is less affected by slowing server sales, will grow faster at 44 per cent.

Over the 5-year period from 2008 through 2013, however, IDC thinks external disk storage systems revenue will show a 1.9 per cent compound annual growth rate (CAGR), despite the 2009 decline. Here IDC is assuming a 30 per cent annual decline in the cost per GB of external storage - 4TB 3.5-inch SATA drives here we come.

The external disk storage systems market - the network disk storage systems segment, or NAS plus what IDC calls Open SAN - will show an insignificant decline this year, even growing in some geographies, and should then grow steadily to and during 2013. IDC thinks iSCSI SANS will be the main driver.

Within the network disk storage systems market, the Open SAN segment will decline in 2009 but grow in 2010 and beyond. This implies that NAS will not decline this year but will grow a little and then keep on growing. ®