Gartner Inc. released the latest market share figures for external, fabric-attached, IP SANs and network-attached storage at its Storage Summit in Orlando this week.

According to Roger Cox, research vice president for Gartner, EMC led the external controller-based storage market with a 23.5 percent market share. HP followed in second with 14.8 percent and IBM trailed in third with 14.5 percent market share.

Hitachi Data Systems, Dell, Network Appliance, Sun and Fujitsu Siemens followed these leaders with single-digit market share percentages.

In fabric-attached storage -- those arrays that connect to a Fibre Channel storage-area network -- EMC again led with a 26.5 percent market share. EMC was followed again by HP with 19.1 percent and IBM with 12.1 percent.

IP storage -- arrays that connect to the Gigabit Ethernet network via the iSCSI block-based protocol -- showed the most surprising results. Network Appliance led EMC with a 45.4 percent market share. EMC's IP storage arrays accounted for a 22.3 percent market share. HP and Dell followed with single-digit market share percentages.

In NAS, Network Appliance squired a 55.9 percent market share, followed by EMC with 12.9 percent. This (writes Chris Mellor) is a suprising result. To those of used to IDC numbers the spat between NetApp and EMC over who has the lead in the NAS market is a regular occurrence. Now Gartner says EMC has a low penetration of this market while NetApp has over half. Thus, last year Techworld wrote that in 2004 NetApp had a 39 percent share whilst EMC had a 33 percent share.

What is going on? The market buying patterns can't have changed in such a startling fashion. It's more likely to be gross differences between Gartner and IDC counting patterns and, until some objectivity can be attributed to the numbers it's best to take these NAS market shares as being as reliable as the wind.