Friday, March 20, 2009

DC Power in the Data Center one step closer to mainstream

Hey everybody,
Hope this post finds you all well.

Something I previously posted on earlier this year was the entry of DC power into the Data Center. This is now one step closer to being mainstream with the introduction of the new HP ProLiant Generation 6 servers (due to be released soon).

These new G6 servers will have the option of a new power supply – DC power input rather than AC.

To understand where the benefits lie in DC power, one must firstly understand how your AC power comes through the Data Center and eventually arrives into the server:
1) Typically the facility will be supplied with high voltage AC power, which will then go through a power conversion to get down to local AC input (110 or 240 Volts for example)
2) The power will then go through an initial conditioning and UPS system (which will typically convert the power from AC to DC to go through the battery and conditioning process, and then back to AC power). Obviously with these conversions power is lost due to the AC to DC and then DC to AC process, and also due to heat exchange
3) The conditioned power is then sent over to the rack level, where there would be a Power Distribution Unit (or possibly another rack level UPS). Power is lost here too because of heat dissipation and possibly an additional AC to DC and then DC to AC conversion
4) The AC power then enters the server and the server’s own power supply will then convert the AC power down to DC power as all of the computers components actually run on low voltage DC power. Again here power is lost due to the AC to DC conversion process and also heat dissipation.

This process typically will have between 4 to 8 AC to DC and DC to AC power conversions, where an enormous amount of power is lost in each conversion.

Now when DC is supplied to the server:
1) The high voltage AC power coming into the building is directly converted to high voltage DC power
2) This DC power will go through the initial conditioning process (note no AC to DC conversion necessary)
3) The conditioned DC power is then sent over to the rack level, where it will go through a PDU and possibly another UPS (note again no AC to DC conversion). The voltage is dropped down to an acceptable server level power input
4) The power enters the servers power supply which again drops the voltage down to internal component voltages (note again no AC to DC conversions)

This process reduces the AC to DC conversions to 1, which greatly reduces the amount of power loss due to the conversion and heat dissipation.

Research shows that by eliminating these conversions, a saving of 10 to 20% power consumption in a large facility is possible.

It’s still early days yet, but with HP jumping onboard with their new G6 servers, I believe this is a technology to watch out for in 2009 and 2010.


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