Power and cooling

Lately, the most discussed subject in datacenters is Power and Cooling. Why is this such a big issue all of a sudden?

Power bill

Usually a system administrator or a datacenter operator knows what a typical server cost. How many of them know what a kilowatt-hour (kWh) of energy costs? Do YOU know? And who pays that bill? The IT departyment?

The typical power consumption of a full-blown datacenter, including air-conditioning today is in the order of several megawatts. With a power price of 6 dollar cents per kWh (which is typically what large customers pay), the power bill of one megawatt is $1440 per day and $525,600 per megawatt per year!

In 1999, the price of a barrel oil was 11 dollar. Now, the price is 120 dollar. This means that the price of energy is rising at an incredible speed, and there is no end in sight. Therefore, the power bill will go up the coming years, and more attention should be paid to reducing the power consumption in datacenters.

It becomes now viable to place new datacenters in the neighborhood of “green” power plants, like water dams (the water can also be used to cool the datacenter). The cost of moving data through a fibre optics cable is much less than the cost of moving energy from a energy plant to a datacenter.

Lower consumption

For every dollar spent on servers, the same amount is spent on power. Not only the kWh´s of the server itself must be paid, but also on cooling the system, the cost of expanding the air-conditioning system and the uninterruptable power supply (UPS).

Therefore it is a good financial investment to try to keep the power consumption of servers low. A typical Intel CPU in 2005 used ten times more power than the same CPU capacity today. This brought the energy bill down considerably. Therefore, the focus for Intel these days is not to increase the speed of a CPU, but to lower the power consumption. The money saved in power, UPS systems and cooling could be invested in more (low power) CPU’s.

Virtualization is another method to decrease power consumption. Not only can resources be better utilized, and CPU’s used as efficiently as possible, but also the possibility to move running virtual machines to other physical machines (using for instance vMotion from VMware) can reduce hot spots in the datacenter.

This entry was posted on Friday 12 September 2008