End-user adoption of Linux servers for enterprise workloads hosting ISV applications and databases is ramping up rapidly, with newly published data indicating that uptake of the operating system has doubled over the past year.

According to the latest research from IDC, the annual growth rate of Linux server unit shipments has been rocketing over the past three years, from 15 per cent in the second quarter of 2001 to 40 per cent in the same period in 2004.

The analyst firm noted that the mix of form factors for these Linux servers has also been changing over time, with the result that dual-processor systems predominate, followed by one-processor and four-processor systems.

Between 1998 and 2003, the one-processor segment of the Linux server market grew at a healthy compound annual growth rate of 37.5 per cent.

However, this sector was eclipsed by the growth of dual-processor systems which clocked up a rate of 89.8 per cent from 1998 to 2003. This format currently accounts for three quarters of total Linux server shipment volume in the market today.

"In the past few years, we have seen an increasing number of organisations adopt and deploy Linux for basic infrastructure workloads, in part driven by their focus to reduce overall IT acquisition costs," said Jessica Yang, research analyst for modular server solutions at IDC.

"More recently, customers are beginning to consider Linux servers for databases and other enterprise applications. We will see the Linux server platform become more diverse and take on more workloads over time as Linux server adoption broadens."

The study found that the trend to move enterprise workloads on to Linux server platforms is being boosted by the release of Linux 2.6, which supports scalable servers, strong support from enterprise middleware players, and the ability of Linux servers to take on stronger roles as database engines for multi-tiered computing infrastructure.

"Customers will be able to deploy Linux workloads on scale-out clusters of small Linux servers, on Linux servers with larger form factors, or in partitions of high-end enterprise scalable servers," said Jean Bozman, vice president for enterprise computing at IDC.

"The choice of form factor for deployment of a given workload on Linux servers will depend on customer preferences and on workload type."

Linux was found to represent about half of the worldwide server blade market, in terms of unit shipments, compared to 20 per cent of all rack-mounted servers and 11 per cent of all pedestal (standalone) servers.

The IDC research predicted global Linux server customer revenue to reach $9.1bn in 2008, driven by a compound annual growth rate of 22.8 per cent, compared to 3.8 per cent for the worldwide server market.

IDC forecasted that Linux server shipments will represent 25.7 per cent of worldwide server shipments in 2008, up from 15.6 per cent in 2003.