At Backblaze, we provide unlimited storage to our customers for only $5 per month, so we had to figure out how to store hundreds of petabytes of customer data in a reliable, scalable way—and keep our costs low. After looking at several overpriced commercial solutions, we decided to build our own custom Backblaze Storage Pods: 67 terabyte 4U servers for $7,867.

In this post, we’ll share how to make one of these storage pods, and you’re welcome to use this design. Our hope is that by sharing, others can benefit and, ultimately, refine this concept and send improvements back to us. Evolving and lowering costs is critical to our continuing success at Backblaze.

Petabytes on a budget: How to build cheap cloud storage | Backblaze Blog

I came accross an interesting article that addresses some of this concern with the suggestion that IT needs to learn how to build and manage the Private Cloud:

One of the biggest strategic challenges facing IT organizations today is remaining competitive in a world full of cloud services that essentially outsource the IT function.

How to Build Private Clouds – IT Management

Most data centers operate in a temperature range between 68 and 72 degrees, and some are as cold as 55 degrees. Raising the baseline temperature inside the data center – known as a set point – can save money spent on air conditioning. Data center managers can save 4 percent in energy costs for every degree of upward change in the set point, according to Mark Monroe of Sun Microsystems, who discussed data center set points at a conference last year. But nudging the thermostat higher may also leave less time to recover from a cooling failure, and is only appropriate for companies with a strong understanding of the cooling conditions in their facility

Google: Raise Your Data Center Temperature « Data Center Knowledge

So how much does it cost to power 100TB (raw) of storage, and how much CO₂ emissions are generated per year? That, of course, depends on the type of storage, the number and size of the disk drives, the cost per kWh of power, cooling costs and the average number of lbs of CO₂ produced per kWh.

One example is a single storage system using 750GB SATA disk drives yielding 144TB of raw storage in a single cabinet footprint, which would require less than 52,560 kWh and cost about $10,512 per year with an emissions footprint of about 39.42 CO₂ tons. To account for cooling costs, simply double the above numbers for a worst-case scenario. By comparison, a 1999 Chevrolet Tahoe generates about 7 to 10 tons of CO₂ per year, while a Lexus RX333, depending on miles driven, generates about 5-6 tons of CO₂ per year, and a 24 cubic foot refrigerator yields about 1.22 tons of CO₂ per year.

Storage Power and Cooling Issues Heat Up