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A power play for the data centre


South Africa has some of the cheapest electricity in the world but paradoxically it is one of our scarcest resources, writes Bernard Donnelly, enterprise solution service head at Unisys Africa.

Take Eskom – it is in the strange position of asking its customers to use less of its product and is paying them subsidies to convert to alternative energy sources.  In the corporate environment this energy shortage is equally apparent.
Increasingly, IT managers are being told there is no more electricity available for their datacentre, forcing organisations to consider either relocating datacentres to accommodate their continuing growth or to look at other strategies to reduce power consumption.
A moderate sized datacentre with 100 servers and 10Tb of networked storage uses 1 300 MWh of energy per year.  It is estimated that worldwide datacentres represent 2% of global energy consumption; about the same as all the world’s airlines.
With ever-increasing demands on IT, how do organisations rationalise energy consumption in the datacentre whilst still accommodating this growth?
In an attempt to reduce consumption, organisations are increasingly turning to server consolidation using virtualisation technologies, such as VMware.
Studies have shown that the typical server in the datacentre is running at between 10% and 15% average utilisation. Virtualisation provides an excellent technology to consolidate workloads onto fewer servers running at higher utilisation.
While not all x86 servers can be virtualised, we have found that typically 60% are good candidates. Consolidating these servers can save 650 MWh of electricity per year – reducing energy consumption by 50%, bringing a significant impact on both the company bottom line and helping solve the data centre sprawl dilemma.
Storage is another area where savings can be made in energy consumption. Storage arrays are typically configured for performance with low-capacity, high-performance drives.
When we examine data usage, however, we find that over half the data on a normal SAN typically has not been accessed in the last three months. Moving this data to lower speed, higher capacity disks can significantly reduce energy costs: Per terabyte of storage, high performance drives use four times the energy of slower high-capacity disks.
Making this substitution in the data centre can save another 40MWh of energy, not as much as consolidating servers but still a critical reduction if it saves you having to build a new multi-million rand data centre.
Combined, these two common strategies can reduce the energy consumption by over 50% and extend the life of a datacentre. However, there is another imperative driving energy reduction: global warming. In Europe organisations are being compelled to reduce their CO2, one of the principal greenhouse gases, and the developed countries that signed the Koyto Protocol are obliged to reduce CO2 emissions by 2012 to 95% of their 1990 levels.
For most countries this represents a 15% reduction in current emissions. South Africa is a signatory to the protocol but, as a developing nation, is not bound by reduction targets. The Kyoto Protocol does, however, demonstrate the increasing pressure being brought to bear on countries and organisations to reduce emissions. It is only a matter of time before this impacts us in South Africa.
In the average organisation, datacentre energy consumption represents 9% of total energy consumption.  For example, a datacentre of 1 300 MWh annual consumption represents nearly 3 000 tonnes of CO2 over the typical five year life of equipment. Applying our two energy reduction strategies can reduce CO2 emission by 1 480 tonnes and reduce the organisation’s energy consumption by 4,5%, a significant contribution to Kyoto-level targets.
As IT organisations are being increasingly constrained by the energy available for their datacentres, server consolidation and storage rationalisation provide two viable strategies that can reduce datacentre power consumption by half – whilst at the same time contributing to the reduction in greenhouse gasses.