Facebook Cold Storage System

To read this article on a blog of Facebook, click on:
Under the hood: Facebook’s cold storage system
The data centers are equipped with less than one-sixth of the power available to our traditional data centers, and, when fully loaded, can support up to 1EB per data hall. After modifying Open Rack to support these power-related hardware tweaks, we were able to build racks with 2PB storage (using 4TB drives) and operate them at one-quarter the power usage of conventional storage servers.