Most, if not all, the hard drive manufacturers have come out with green drives; drives that spin down or turn off. There are two problems with counting on green drives to reduce your power consumption; first, they are only one component in the storage solution, and second, there has to be intelligence for them to be used optimally.The classic "let's jump on the marketing hype" manufacturer response to greening storage is to simply certify these green drives and put them in their existing shelves. The problem is the existing shelves still consume the same amount of power, as does the rest of the storage system. Clearly, spinning down or turning off drives will reduce some of the power consumption of the storage platform, but the shelves that these drives will go into can be responsible for haf of the power consumption and cooling on a per-shelf basis.

Storage solutions that are advocating themselves as green need to have the intelligence to power down the shelf itself or at least not require as much power on a per-shelf basis.

Even if the shelf power management issues can be resolved, a green storage system must have more intelligence for data placement than does a traditional storage solution. Drive power savings counts on the drives not being accessed long enough for them to go into an idle or power-down mode. They have to continue to not be accessed long enough to make sure you get the proposed power savings out of them.

Intelligent placement is the key and I'm not sure how the "place green drives in our shelf" crowd plans on making this happen. Their basic guideline is to have the user manage the placement of that data to different shelves for array groups as needed. Really? Last time I checked, storage administrators had more than enough to worry about without adding the "OK, what data should I put where and when is the next time it makes sense to do that."

The data placement must be automated so data can be moved to cooler and cooler drives as it gets older, without requirement of extensive user management. This also could be timed with the drive-checking routines that these systems run to make sure the drives are still viable -- basically a maintenance period that would spin the drives up, make sure they are working and then move older data to them, then let the drives spin down again.

In primary storage, while I would debate that green drives even belong in primary storage, there are a few manufacturers that offer green drives, but what is lacking is the ability to manage data placement to complement power efficiency. Look for vendors that can manage data placement today and then ask them what their plans are for green drives.

In archive, where green drives make a lot of sense, look for vendors that can not only spin down or power off the drives, but also the shelves and other components. Also look for vendors that can manage where that data is written so they can maximize the amount of time the data is able to be stored on a powered-off drive.

We will cover more on this subject in our upcoming Webcast, Demystifying Primary Storage Data Reduction.

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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.