Comments on: Myth-of-the-Month: PUE, Part 2 http://knowledge.digitalrealtytrust.com/2009/12/myth-of-the-month-pue-part-2/ Wed, 16 Dec 2009 12:33:31 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: ghaley http://knowledge.digitalrealtytrust.com/2009/12/myth-of-the-month-pue-part-2/comment-page-1/#comment-94 ghaley Wed, 16 Dec 2009 12:33:31 +0000 http://knowledge.digitalrealtytrust.com/?p=1135#comment-94 I look forward to the next installment of this myth. I have been preaching that PUE is an ongoing process rather than a report card on progress. Data centers are dynamic environments, with adds, changes and deletes constantly going on. Regular readings need to be taken to develop a trend chart to demonstrate the inpact of changes that have been made over time. Not all energy saving changes will result in a better PUE calculation. The implementation of virtual servers may reduce the overall energy consummed by the IT load, but may not be enough of a BTU saving to reflect reduced cooling expenses. You net result is a reduced energy expense (less IT load) but a higher PUE as the infrastructure expense remains constant. I always stress that one should not fall in love with the numbers, rather the overall results of the changes. Use the calculations as a tool to monitor your trend and have the knowledge of what impact each change has made to the overall operation. Keep up the good work. Gregg Haley Principal Gregg Haley & Associates I look forward to the next installment of this myth. I have been preaching that PUE is an ongoing process rather than a report card on progress. Data centers are dynamic environments, with adds, changes and deletes constantly going on. Regular readings need to be taken to develop a trend chart to demonstrate the inpact of changes that have been made over time.

Not all energy saving changes will result in a better PUE calculation. The implementation of virtual servers may reduce the overall energy consummed by the IT load, but may not be enough of a BTU saving to reflect reduced cooling expenses. You net result is a reduced energy expense (less IT load) but a higher PUE as the infrastructure expense remains constant.

I always stress that one should not fall in love with the numbers, rather the overall results of the changes. Use the calculations as a tool to monitor your trend and have the knowledge of what impact each change has made to the overall operation.

Keep up the good work.

Gregg Haley

Principal
Gregg Haley & Associates

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