Sneak peek at our new White Paper

June 6, 2007 at 7:18 am | Posted in Technical | Leave a comment

As part of the work we do for our customers, DCC has started a series of white papers. Our goal is to answer a lot of the questions lurking behind the scenes of our clients’ IT shops.  As the writing-addicted member of the staff, naturally I’m involved in putting this document together. I love to write papers, because inevitably I find something in my research that is simply not what I’d have expected to find.

For instance, right now I’m writing about data center energy efficiency. In the interest of writing a thorough, well-researched paper,  I’m  fact-checking everything, even things that seem to be common sense. A larger capacity hard drive, for instance, consumes more energy than a smaller one of the same type. That makes sense, right? The manufacturers’ specifications for those drives lists their wattage requirements, and sure enough, the greater capacity drives require more watts to spin and idle.

Ergo, to be more energy efficient, stick with smaller drives… or so I would have thought. Then, consider that I’m writing about a data center, which has a large array of disks. From a space perspective, it’s more efficient to have larger drives, so I decided to examine the cost of using that extra energy compared with the square footage consumed by using more drives with a smaller capacity.

It turns out that if you look at it in terms of watts per gigabyte, larger drives are the way to go. Here’s a sampling of my results:

Drive

Energy Required Watts/GB
Samsung SATA 120 GB (7200 RPM) Seek: 9.5 W

Idle: 7.7 W

Standby: 0.9 W

.07 w/GB

.06 w/GB

.007 w/GB

Seagate SATA750 GB (7200 RPM) Seek: 12.6 W

Idle: 9.3W

Standby: 0.8 W

.016 w/GB

.012 w/GB.

.001 w/GB


Hitachi Deskstar SATA 1TB (7200 RPM)
Seek: 13.6 W

Idle: 9 W

Standby: 0.9 W

.013 w/GB

.008 w/GB

.0008 w/GB

 These are, of course, based upon the seek, idle, and standby times provided on the manufacturer spec sheets, and they are averages. Still, it seems pretty clear to me that in an array scenario when you’re trying to squeeze the most possible storage out of your available space and wattage, larger drives are better.

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