In the second annual Cisco Global Cloud Index (2011-2016) Cisco forecasts global data centre traffic to grow fourfold and reach a total of 6.6 zettabytes annually by 2016.

The company also predicts global cloud traffic, the fastest-growing component of data centre traffic, to grow six fold – a 44% combined annual growth rate (CAGR) – from 683 exabytes of annual traffic in 2011 to 4.3 zettabytes by 2016.

For context, 6.6 zettabytes is equivalent to: 92 trillion hours of streaming music – equivalent to about 1.5 years of continuous music streaming for the world’s population in 2016;16 trillion hours of business Web conferencing – equivalent to about 12 hours of daily Web conferencing for the world’s workforce in 2016; and 7 trillion hours of online high-definition (HD) video streaming – equivalent to about 2.5 hours of daily streamed HD video for the world’s population in 2016.

The vast majority of the data centre traffic is not caused by end users but by data centres and cloud-computing workloads used in activities that are virtually invisible to individuals. For the period 2011-2016, Cisco forecasts that roughly 76% of data centre traffic will stay within the data centre and will be largely generated by storage, production and development data. An additional 7% of data centre traffic will be generated between data centres, primarily driven by data replication and software/system updates. The remaining 17% of data centre traffic will be fuelled by end users accessing clouds for Web surfing, emailing and video streaming.

From a regional perspective, the Cisco Global Cloud Index predicts that through 2016, the Middle East and Africa will have the highest cloud traffic growth rate, while the Asia Pacific region will process the most cloud workloads, followed by North America.