10 IT Power-Saving Myths Debunked

snydeq writes "InfoWorld examines 10 power-saving assumptions IT has been operating under in its quest to rein in energy costs vs. the permanent energy crisis. Under scrutiny, most such assumptions wither. From true CPU efficiency, to the life span effect of power-down frequency on servers, to SSD power consumption, to switching to DC in the datacenter, get the facts before setting your IT energy strategy."

Comments

I dunno..

[Anrego]

I'm of the school that thinks "debunking" involves some kind of comprehensive stats or numbers or evidence weight against strongly held opinions.

This article is basically a verbose version of the "nuh uh" argument.

It's not a bad article.. but I would hardly call this "debunking".

And I totally disagree on point #2 .. maybe having _all_ your extra servers always on is bad.. but if load peaks there is no _way_ someone should be waiting while a system boots.

Re:I dunno..

[gnick]

FTA:

Hibernate mode in XP saves the state of the system to RAM and then maintains the RAM image even though the rest of the system is powered down.

They must be using a different version of XP than I am... When I 'Hibernate' my laptop, it dumps the RAM to a file on the hard drive and then powers off completely. When I 'Stand By' my system, it keeps everything in RAM.

Maybe they have SP4...

Re:I dunno..

[ShieldW0lf]

I've got electric heat, and I've got a pile of servers in my spare bedroom, and I never need to turn on the electric heat, because the servers heat my home.

Which looks to me like an opportunity. People pay for heat. So, put the servers where people need heat, and suddenly a liability is a resource.

Apartment buildings, office buildings and malls in cold climates should all be prime locations for a datacenter.

Re:I dunno..

[snowraver1]

If you are using electric heat, chances are you don't live in a cold climate and pay for air conditioning for much of the year negating any "savings". Here in cold-balls Canada, EVERYONE has centeral heating; it's too expensive to use electricity. That being said, I do agree that datacenters' heat should be used to heat useful things (office bldgs, like you suggest).

Re:I dunno..

[R2.0]

I stopped reading at #1: "Fact: The same electrical components that are used in IT equipment are used in complex devices that are routinely subjected to power cycles and temperature extremes, such as factory-floor automation, medical devices, and your car."

Well, yes, except for the fact that the it's a total lie. Cars, factory automation, and medical devises most certainly do NOT use "the same" components. While they may do the same things, and even be functionally equivalent, they are rated to much higher temperature and stress levels than consumer or even server grade components. Just ask the folks who have been trying to install "in-car" PC's with consumer grade components.

Re:I dunno..

[halcyon1234]

hey must be using a different version of XP than I am... When I 'Hibernate' my laptop, it dumps the RAM to a file on the hard drive and then powers off completely.

You must be using a different version of XP than I am... When I 'Hibernate' my laptop, it attempts to dump the RAM to a file, throws a hissy fit like a coddled freshman after their first exam, fails miserably, flickers the screen, disables the Hibernate option, and then just sits around until the battery drains.

Re:I dunno..

[R2.0]

You're right.

They don't use Transistors, Inductors and Capacitors at all, do they?

Functionally, the devices might not be used to perform the same precursory things... However, silicon is silicon, capacitors are still made from the same things, and inductors are little more than (get this!!!) lumps of a constant controlled by the turns ratio and other things.

Nope, totally different animals, huh?

Right. And I'm the same as Albert Einstein because I have DNA, amino acids, and funny hair. Where's my Nobel Prize?

A Pinto is the same as a Mercedes because it's made of steel, has 4 wheels, and an engine. I want $75,000 for my used Ford.

My wife is the same as Elle McPherson because she has hair, tits, and a vagina. My wife should be the supermodel (no, really, honey, I was serious on that last one. No, wait...WAIT!...")

Sleep != Hibernate

[Taimat]

Myth No. 6: A notebook doesn't use any power when it's suspended or sleeping. USB devices charge from the notebook's AC adapter. Fact: Sleep (in Vista) or Hibernate mode in XP saves the state of the system to RAM and then maintains the RAM image even though the rest of the system is powered down. Suspend saves the state of the system to hard disk, which reduces the boot time greatly and allows the system to be shut down. Sleeping continues to draw a small amount of power, between 1 and 3 watts, even though the system appears to be inactive. By comparison, Suspend draws less than 1 watt. Even over the course of a year, this difference is probably negligible.

um... Hibernate != Sleep. Hibernate in XP saves the RAM to the Hard Drive, and powers off. Suspend keeps RAM powered....

Re:Sleep != Hibernate

[EvilRyry]

Using my handy killawatt, I tested how much power my desktop (not including accessories) draws while off, on and idle, on and under load, and in S3 suspend.

Off - 6 watts
Idle - 140W (dropped from 152W after installing a tickless kernel)
Loaded - 220W
S3 - 8 watts

Ever since I ran that test, I put my machine into suspend at every opportunity. 140W is a lot of juice in the land of $0.18/kWh.

Re:Sleep != Hibernate

[afidel]

How about build an energy efficient PC! I have a LP AMD 64 x2 with a Geforce 7600GS, 2 HDD's, 2GB of ram and a TV tuner and an 85% efficient PSU and I peak at around 150W, using 140W at idle is insane. For the next generation of games I'm thinking about upgrading to a 9600 GSO but that will up my idle and peak numbers by at 20W so I'm holding off till I get a game that really needs it.

Questionable grasp on the problem space.

[Anonymous Coward]

Myth No. 3: The power rating (in watts) of a CPU is a simple measurement of the system's efficiency.
Fact: Efficiency is measured in percentage of power converted, which can range from 50 to 90 percent or more. The AC power not converted to DC is lost as heat...Unfortunately, it's often difficult to tell the efficiency of a power supply, and many manufacturers don't publish the number.

I'm not sold on taking advice who doesn't understand the difference between the wattage rating of a CPU and the wattage rating of the power supply. They're completely different components.

Re:Questionable grasp on the problem space.

[Anonymous Coward]

I like how this plays with the following assertion filed under "Myth No. 9: Going to DC power will inevitably save energy."

"New servers have 95 percent efficient power supplies, so any power savings you might have gotten by going DC is lost in the transmission process."

So, when it suits his argument, power supply efficiencies range from 50-90% efficency, and are kept hidden by manufacturers. Then, when that doesn't suit his argument, all of a sudden power supplies are at least 95% efficient, and everyone knows that.

I call shenanigans!

Re:Questionable grasp on the problem space.

[gmack]

Myth No. 9: Going to DC power will inevitably save energy.
Fact: Going to DC power entails removing the power supplies from a rack of servers or all the servers in a datacenter and consolidating the AC-DC power supply into a single unit for all the systems. Doing this may not actually be more efficient since you lose a lot of power over the even relatively small distances between the consolidated unit and the machines. New servers have 95 percent efficient power supplies, so any power savings you might have gotten by going DC is lost in the transmission process. Your savings will really depend on the relative efficiency of the power supplies in the servers you're buying as well as the one in the consolidated unit.

This is completely wrong. The author missed out on two of the three power conversions that take place in a data center. Data center UPS units take the AC current convert to DC then back again just so the server can convert it back to DC. Even if you have 95% efficiency at each stage the conversion losses will add up.

People wouldn't be going DC if it didn't result in measurable power savings.

Debunk this

[sargeUSMC]

Taking ten suppositions and making suppositions about those suppositions (I'm getting dizzy) is not debunking. All I see here is lots of questionable, completely unattributed information. For example: "The average 17-inch LCD monitor consumes 35 watts of electricity". Really? Where did this information come from? Did you pull this information from the glossy for a 17" monitor? Did you just test your monitor? Did you test a large sample of monitor's here? Did you pull this information from a study? Out of your ass?