How much power could be saved?

It’s already known virtualization can significantly reduce datacenter costs through server consolidation and related power saving.
Numbers are so big that in November 2006 Pacific Gas and Electirc Company announced an incentive program to help companies adopting server virtualization.

But virtualization will, sooner or later, become interesting on storage and network too, so it’s worth to consider how the power is used by infrastructures.

Computer Business Review published an article which spreads some lights about this topic:

…studies Cisco has carried out with APC and Emerson Network Power indicate that servers and storage together are responsible for approximately 26% of the power consumed by an average data center, with networking equipment responsible for about 11%. Power conversion losses account for a further 10%, while 3% goes in lighting the data center room, leaving 50% for air conditioning.

This breakdown differs somewhat from figures used by Hu Yoshida, CTO of storage vendor Hitachi Data Systems, who estimates 25% for servers, 25% for storage, and 50% for networking, but Aldrich said the discrepancy might be the result of the way Yoshida defines his categories.