Google's PUE

Jean-François Mezei jfmezei at vaxination.ca
Wed Oct 1 17:11:03 CDT 2008


Google not counting electricity losses from power cords etc gives the
image that it doesn't really want to account everything and want to skew
the numbers as much as possible.

I would be far more interested in a metric that shows the amount of
power used for each MIPS of CPU power (or whatever CPU horsepower metric
other than clock speed). And also amount of power used for each gbps of
telecom capacity USED.

Another metric would be how much power is used to store how many
terabytes of data on disk. Disks consume much power too.

In the case of Google, the amount of data they spit out to the internet
would be a good metric of how much work is being done. So how much power
is consumed per gigabyte of data spitted out to the internet would be a
good metric of how efficient the data centre is. But for a bank, this
would not be a good metric since a lot fo the work doesn't involve
sending much data in/out. (because much of the work of a transaction
involves a lot of validation/logging)

To me, it seems that PUE is just a metric of how efficient the air
conditioning is. Not really how energy efficient the whole data centre
is for how much work it does.




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