Worldwide external disk storage systems factory revenues were down 10% to $4.4 billion in the third quarter of 2009, compared to $4.86 billion in same period last year, according to research and analytic firm IDC.

The study showed that the total disk storage systems market declined to $6 billion in revenues, a 9.6% decline from the prior year’s third quarter revenue of $6.6 billion, driven by continued weakness in server systems sales. Total disk storage systems capacity shipped reached 2,661 petabytes, growing 21% year over year.

EMC gained the first spot in external disk storage systems market with revenue of $1.06 billion,accounting for a market revenue share of 24.2%, while IBM stood second with revenue of $577m and 13.2% revenue share. HP with revenue of $517m, ended the quarter in the third position with 11.8% market share. Dell and NetApp finished the quarter with 9.3% and 8.7% revenue share, respectively, IDC reported.

According to the report, total network disk storage market declined 7.6% year over year in the third quarter to $3.4 billion in revenues. EMC continues to maintain its leadership in the total network storage market with 29% revenue share, followed by IBM with 12.5% revenue share.

In the Open SAN market that declined 16% year over year, EMC maintained its lead with 24.4% revenue share. The NAS market grew 2.2% year over year, led by EMC with 46.4% revenue share and followed by NetApp with 24.5% share. The iSCSI SAN market continues to show strong momentum, posting 24.7% revenue growth compared to the prior year’s quarter. Dell led the market with 33.6% revenue share, followed by EMC with 15.1%.

Steve Scully, research manager of enterprise storage at IDC, said: Although the external disk storage market posted another year-over-year decline in the third quarter, the rate of decline has started to slow. Moreover, the market experienced a sequential gain over the previous quarter, with many of the top storage vendors posting increases. The stability in the storage market that IDC first began to see last quarter is now being felt more broadly by storage vendors.