ways sought to cut power use amid exponential it growth

Reducing the power consumption of data centres has been a major challenge for the information-technology industry over the past decade, given the unrelenting growth of information-technology (IT) systems around the world.

US-based NetApp said a simple strategy is to subtract machines and disks from the power equation by using data storage facilities more efficiently.

This strategy has many other benefits, including lowering network complexity, people's costs, and support and service costs while improving network efficiency and performance.

Based on the IDC Worldwide Disk Storage Systems Forecast (2006-10), worldwide data will expand at a compound annual growth rate of 50.6 per cent over the next few years.

Such exponential growth is a big worry for IT managers. Until recently, continuous improvements in price/performance and US$/£ exchange rates had made it both easy and affordable to solve storage concerns simply by adding more disks to existing storage systems.

However, there are limits to that easy growth; namely, floor space, weight loads, power connections, cooling infrastructure - and even power itself is a finite resource.

For example, cooling is directly linked to power consumption as every watt that enters the data centre generates heat that must be removed from the environment. And to do so takes more power.

In other words, a watt "in" means a watt "out" or the cost of cooling a system could be as much as the cost of powering the system itself.

Moreover, the combined effect of recent increases in the price of energy and the adoption of denser computing and storage architecture has driven energy costs for certain data centres to 30 per cent of total operating costs.

If unchecked, the cost to power IT equipment could exceed its acquisition cost in a matter of years.

To address this issue, it is necessary to consolidate computer servers and data storage facilities; use higher-capacity disk drives; move data to more efficient storage; and increase storage use from an average of 25-40 per cent to a higher rate, to minimise the unused portion.

Do more with less on backup, eliminate storage overhead for testing and development, and measure your power efficiency.

On storage use, you can calculate the power efficiency by dividing the total watts per system by the total number of TBs (terabytes) in that system, and times the system-use rate.

System use is equal to the percentage of your disks that are actually available for use.

For example, a 30-per-cent use rate of a 30TB system translates into a watts/usable TB ratio of 555 watts, compared with a ratio of only 278 watts - a 50-per-cent improvement - if the use rate of the same system is 60 per cent. That is a huge saving.

Looking ahead, the industry also explores other power-saving technologies such as larger disk drives, in-line hardware data compression, file de-duplication, flash memory, more energy-efficient CPUs or intelligent control of the speed of individual drives in response to demand.

In this context, future reductions of power consumption will be achieved through a combination of various efforts.