'Power Capping' the Datacenter

snydeq writes "Datacenter operators seeking increased server density may soon turn to power capping, an emerging technology that limits the amount of electricity a server can consume, InfoWorld reports. The practice, which can be applied at the rack level, ensures that no server draws above a set power level, thereby increasing datacenter capacity within a rack-level power envelope by as much as 20 percent, according to a proof-of-concept study at Baidu, China's largest search company. As with powering down servers during off hours, of course, power capping incurs calculated risk, as those in charge of business-critical applications may be reluctant to set power limits below maximum utilization. Yet given IT's need to contend with the permanent energy crisis, the notion of power capping the datacenter could prove advantageous."

pointless

[MagicMerlin]

lame...a much better way of handling this is what datacenters are already doing: simply sell you power circuits, say 20 amps each for a set price. if they want to discourage power use, they simply have to raise the price. low tech, and works perfectly well. you can always get a good power strip with a ammeter on it if you want to know what your servers are drawing.

Not a crisis

[tsotha]

"Permanent energy crisis"? There's no such thing as a permanent crisis. Yes, energy costs are going up because we're more sensitive to the impact of new capacity. But that hardly constitutes a crisis. The word "crisis" has been practically stripped of meaning - everything these days is a goddamn crisis. When the girlfriend you were about to dump gets pregnant - that's a crisis. A few bucks more on your energy bill - not a crisis.

Power management

[westlake]

Tell me why it doesn't make sense to buy power at off-peak rates and store it locally to meet peak demands.

Our Policy

[teknopurge]

I can't see any legitimate provider capping power usage. We have 20A running to a client rack by default - if they need more circuits we charge them per circuit. The only place I can see people wanting to make an argument for capping power usage is if a provider has oversold their power infrastructure and is starting to feel the pinch because they're not charging enough. Same goes for bandwidth: if you want to price things cheaper and cheaper to attract customer, I believe it';s unethical to then raise rates after-the-fact because of poor planning/forecasting.

Another way to overcharge smaller users

[khodsden]

This happens to be why my quarter rack space has only 2 1U computers in it. It was supposed to be a quarter rack (10U), but I was told I had only 7U of space. Okay, not a problem, I can put in 7 1U systems, 14 if I purchase the half sized systems. Then I was told I have only 2A, oh, and here's a switch that'll turn it off if you go over. Which means my quarter rack has two 1U servers in it.

Worse, even the full rack is allowed only 15A before you have to buy a secondary power conduit to the rack at this particular colo.

I suspect it's more a way for the facility to make money than it is to reduce energy usage. When I visited the facility last to move boxes, 4 racks were being emptied and a good 60% of them were completely empty anyway, so the facility may not be long in this economy.
 

Re:Just a friendlier name for...

[frosty_tsm]

It depends what they are overselling and to what degree. Overselling a plane screws whoever is left behind (large impact over small set of customers). Overselling bandwidth slows someone's download or game (small impact over many customers).

Overselling a rack and causing servers to a) fail or b) corrupt data costs in hundreds of thousands or more pretty quickly in damages and legal fees. It's a much wiser business decision to just increase the power capacity (not that some suits will think this is the greatest thing since cloud computing).

Re:Not a crisis

[tsotha]

Sigh. I understand all that, but the numbers are hardly insurmountable, or even very uncomfortable. How many nuclear power plants could we have built for the trillion dollars we spent on "stimulus"? Four or five in every state, by my calculations. The idea that everything is just going to fall apart when the price of oil goes up is just silly.