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The truth behind 10 energy efficiency myths

Which power saving techniques actually work?

Before you start implement energy efficient methods, it's worth thinking about whether they actually work. We've looked at 10 of the most popular energy efficiency myths and investigated whether they are true or not.

In today's energy efficiency focused world, we're all being encouraged to be as green, and consume as little power, as possible, while in the process saving money in the face of soaring energy prices. However, how can you be certain that the power-saving strategies you've adopted are, in fact, the best ones?

After all, there are plenty of myths out there about saving energy that are patently false. We've rounded up 10 popular myths and investigated them to see just how true they are.

1. Powering a computer or server up and down limits its life span

The extreme temperature and current swings of power cycling can stress electronic components (especially capacitors and diodes) in a machine.

Fact: Power cycling healthy electronics is not a source of stress. 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.

There is a kernel of truth in this myth, however: cycling power on a sick system is going to bring attention to latent component weaknesses that go unnoticed in operation. Power-on diagnostics are brief yet rigorous and can be performed remotely on servers with dedicated management controllers. Power cycling doesn't just save energy. It's a zero-cost aid to maximising server availability.

2. It takes too long to cold-start servers to react to spikes in demand

The danger with this is that if customers are made to wait, they'll go elsewhere.

Fact: Idling servers at zero workload as hot spares is an egregious waste of energy and an administrative burden. If customers need to wait while you spin up cold spares to handle rising workload, brag about it. For a website, put up a static page asking users to wait while additional resources are brought online. As for the wait, people will stay on hold if they know their call will be answered. Build power management into your services architecture and make it part of the message that you send to users and customers.

You can also select systems that cold-boot rapidly. Model to model and brand to brand, servers exhibit wide variances in power-up delay. This metric isn't usually measured, but it becomes relevant when you control power consumption by switching off system power. It needn't take long. Servers or blades that boot from a snapshot, a copy of RAM loaded from disk or a SAN can go from power-down mode to work-ready in less than a minute. The most efficient members of a reserve/disaster farm can quiescent in a suspend-to-RAM state rather than be powered down fully so that wake-up does not require BIOS self-test or device querying and cataloging, two major sources of boot delay.

NEXT PAGE: Is it better to pack a server with all it can hold rather than use multiple small servers? We find out.

  1. We investigate which power saving techniques actually work
  2. Is it better to pack a server with all it can hold rather than use multiple small servers? We find out
  3. A laptop doesn't use any power when it's suspended or sleeping
  4. Will going to DC power save energy?

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