Spending on all disk storage rose to nearly US$8.1 billion in the quarter, led by double-digit growth in emerging countries, IDC said. Enterprises also bought more bytes of data capacity, with shipments rising 24.8 percent from a year earlier to 6,667 petabytes.

Midrange storage systems, including modular products that have advanced features but are more affordable than higher-end enterprise gear, were the fastest-growing product category, according to IDC. Those systems may include compression, tiering and data de-duplication, but range in price from $25,000 to $249,999, IDC said. Revenue from midrange platforms grew 12.2 percent, and they are now producing nearly half the revenue in the external storage systems market, the company said.

Total external storage systems, which includes all types of platforms that have three or more disks deployed outside of a server, logged year-over-year revenue growth of 6.5 percent to just under $6.0 billion, IDC said. EMC remained at the front of the external-storage pack with 30.4 percent revenue market share. IBM and NetApp were statistically tied for second place with market shares of 12.9 percent and 12.1 percent, respectively. Hewlett-Packard was fourth with 10.7 percent of the market and Dell came in fifth.

Research company Gartner was set to announce its own second-quarter numbers for external controller-based storage systems on Friday. Its report, which counts products slightly differently, shows external storage system revenue up 6.7 percent to $5.5 billion. That marked the 11th consecutive quarter of growing revenue for external storage, according to Gartner, but fell short of the company's forecast of 7.9 percent growth year over year.

Storage sales in Europe, the Middle East and Africa were particularly hard hit by weak economies, according to Gartner, with 2.6 percent revenue growth compared with Gartner's forecast of 7.4 percent. Asia-Pacific also fell short of expectations. However, North America and Japan exceeded the company's estimates.