According to International Data Corporation (IDC), total cloud IT infrastructure spending (server, storage, and Ethernet switch) will grow by 26.4% in 2015 and will reach US$33.4 billion, accounting for a third of all IT infrastructure spending, up from 28.1% in 2014.

Private cloud IT infrastructure spending will grow by 16.8% year over year to $11.7 billion, while public cloud IT infrastructure spending will grow by 32.2% in 2015 to $21.7 billion, says the research group. In comparison, spending on non-cloud IT infrastructure will remain flat at $67 billion.

IDC expects that spending on cloud IT infrastructure will grow across all regions and all technologies. In most regions, growth in public cloud IT infrastructure spending will exceed growth in spending on private cloud IT infrastructure as public cloud service providers will continue to invest in expansion of their datacenters and service offerings.

For the five-year forecast period, IDC expects that cloud IT infrastructure spending will grow at a compound annual growth rate (CAGR) of 15.6% and will reach $54.6 billion by 2019 accounting for 46.5% of the total spending on IT infrastructure. At the same time, spending on non-cloud IT infrastructure will decline at a -1.4% CAGR. Spending on public cloud IT infrastructure will grow at a slightly higher rate than spending on private cloud IT infrastructure – at 16.5% vs 14% CAGR. In 2019, IDC expects cloud service providers will spend $35.3 billion on IT infrastructure for delivering public cloud services, while spending on private cloud IT infrastructure will reach $19.2 billion.

"End users continue to evaluate various approaches to adopting cloud-based IT: some integrate public cloud service into their IT strategies, others choose to build their own private clouds or use third-party private cloud offerings, and some, seeing benefits in both, implement hybrid cloud strategies," says Natalya Yezhkova, research director, Storage Systems, IDC. "The breadth and width of cloud offerings only continue to grow, with an increasing universe of business- and consumer-oriented solutions being born in the cloud and/or served better by the cloud. This growing demand from the end user side and expansion of cloud-based offerings from service providers will continue to fuel growth in spending on the underlying IT infrastructure in the foreseeable future."