This marked the second consecutive quarter of year-over-year growth as supply chain constraints have depleted vendor inventories over the past several quarters. As backlogs continue to grow, pent-up demand bodes well for future growth as long as the economy stays healthy, and supply catches up to demand. For the full year 2021, cloud infrastructure spending totaled $73.9 billion, up 8.8 percent over 2020.
Investments in non-cloud infrastructure increased 1.5 percent year over year in 4Q21 to $17.2 billion, marking the fourth consecutive quarter of growth. For the full year, non-cloud infrastructure spending increased 4.2 percent over 2020, reaching a total of $59.6 billion.
Spending on shared cloud infrastructure reached $14.4 billion in the fourth quarter, increasing 13.9 percent compared to a year ago, and grew to $51.4 billion for 2021, an increase of 7.5 percent. IDC expects to see continuously strong demand for shared cloud infrastructure with spending expected to surpass non-cloud infrastructure spending in 2022. Spending on dedicated cloud infrastructure increased 12.5 percent year over year in 4Q21 to $6.7 billion and grew 11.8 percent to $22.5 billion for the full year 2021. Of the total dedicated cloud infrastructure, 47.5 percent in 4Q21 and 46.1 percent in 2021 were deployed on customer premises.
For 2022, IDC is forecasting cloud infrastructure spending to grow 21.7 percent compared to 2021 to $90.0 billion, while non-cloud infrastructure is expected to decline slightly, down 0.3 percent to $59.4 billion. Shared cloud infrastructure spending is expected to grow 25.5 percent year over year to $64.5 billion for the full year. Spending on dedicated cloud infrastructure is expected to grow 13.1 percent to $25.4 billion in 2022.