Saving money and going green with RES Wisdom

Sometimes you need to be reminded by someone (thanks Adrie) of the cool things people are doing with RES Wisdom, and the fact that they are earning money with it.

A customer of RES uses about 150 terminal servers. Every night and every weekend they maintain, polish and shutdown two thirds of their farm with RES Wisdom. Right before the start of every working day, these terminal servers are booted up again, batch by batch. There are some nice tasks in RES Wisdom that help you set this scenario up. The task “Shutdown computer” offers an option to “Fail shutdown if user is logged on”. And you can start a server up using either Wake-on-LAN or SSH. I believe that both Dell DRAC and HP iLO support the SSH option, and other vendors will probably do so too.

Now, at first sight, you might think: why bother? It doesn’t sound so amazing – until you start thinking about the electricity saved by this…

Let’s say you shut down 100 servers for 12 hours every night and for the entire weekend. This amounts to 108 hours of electricity saved every week.

Power consumption is measured and billed in kilowatt per hour (kWh) (at least, it is in the Netherlands). Over here, 1 kWh will cost you about 7 eurocents at night (night rates can be lower than day rates).

Taking into account the fact that modern terminal servers have a power supply of about 700 watt, we can estimate how much money is saved by turning servers off:
kiloWatt * hours * weeks * money * servers = money per year

So:

0.7kW * 108 hours * 52 weeks * 0.07 euro * 100 servers = 27.518,40 euro per year!

And that’s a lot of money! If you take the current list price for Wisdom, with this kind of money, you’ll have an ROI of 2 years, just by using this tiny part of Wisdom!

Of course this is not an entirely accurate calculation, because a server seldom uses its power supply to the max. At night, when nobody is logged on, it will use significantly less… On the other hand, a computer produces heat, even when it’s idle. If it’s switched off, your cooling system will not have to work quite as hard and that also saves you money.

So even if you could save half of that amount with your servers – or even a quarter – I still wish I could deposit the resulting amount of money saved on my bank account ;-)