There is an ever increasing emphasis by storage suppliers on the power efficiency of their systems. There is also an increasing interest from IT managers on making their environment more power efficient. This is being driven not so much by the desire to be environmentally sensitive, but more because an increasing number of data centers simply can't get more power to the building.In a situation where there is simply not enough power to go around, the purchase of new storage means that something else has to give. Essentially anything that goes into the data center means that something else has to either come out or be turned off. Storage vendors have been quick to respond to this in a variety of ways.

With power efficiency for primary storage, the goal is to buy less storage upfront, use less of what you have currently and lower the amount of additional physical spindles being added to solve performance issues. Buying less upfront is possibly best served by using thin provisioning so that capacity isn't locked into applications upfront but instead allocated to them as those applications grow. An important component to look for is the ability provided by Symantec, 3PAR and HDS which is space reclamation. As we point out in our article "Keep Thin Provisioning Thin", reclamation is the ability to "re-thin" a volume after data has been deleted from the volume. Without this capability you are essentially only thin once.

The other option is to use less of what you have already. Popular here is deduplication or compression solutions built in to EMC and NetApp solutions or add ons from Storwize and Ocarina Networks. The power savings again is to provide you with the ability to buy less future storage. This is also the case with archive solutions like those from Permabit or Nexsan that feature denser storage to offer higher capacity in the same space.

If archive or capacity optimization can stop the impending purchase of primary storage then it could lead to power savings on installation. Otherwise these techniques lead to future power savings because you don't have to buy as much primary storage in the future.

With capacity optimization and archive you can end up with a significant amount of free space, in some cases 50% or more. Theoretically data could be rearranged so that shelves of storage could be turned off. I'm not sure how many IT teams have the available time to reorganize that data or if it would be worth the effort.

Reality is that if power efficiency is the key driver in the data center then things need to be turned off. In our next entry we will look at how MAID storage has evolved as well as how Solid State Disk can also lead to powering off drives.

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George Crump is founder of Storage Switzerland, an analyst firm focused on the virtualization and storage marketplaces. It provides strategic consulting and analysis to storage users, suppliers, and integrators. An industry veteran of more than 25 years, Crump has held engineering and sales positions at various IT industry manufacturers and integrators. Prior to Storage Switzerland, he was CTO at one of the nation's largest integrators.