SGI's Eco-Logical™ servers and storage are designed to reduce power consumption and increase system-level efficiency and reliability. Leveraging low wattage components with high Mean Time Between Failure (MTBF) ratings — with careful focus on the power supply in a given system — is an important design criteria. Available with both high efficiency Alternating Current (AC) and Direct Current (DC) power supplies, SGI servers and storage systems feature a broad range of power distribution options compatible with any data center design:

In 2003, SGI launched the industry’s first AC-to-DC X86 rack-level rectification technology, enabling any standard Alternating Current (AC) data center to easily deploy Direct Current (DC)-based servers and storage with no changes to existing data center infrastructure. Given the inefficiencies most data centers face as a result of the complex AC-to-DC power conversion path required from the facility exterior to the systems themselves, a DC-based deployment can enable significant power savings and increase system availability without compromising density and performance.

How Does it Work?
Our award-winning rectified AC-to-DC Rack technology enables data centers to bring AC power to each rack and achieve high efficiency AC-to-DC power conversion within the rack itself with no costly infrastructure changes. Rectifiers installed at the top of the cabinet convert AC input power to -48VDC, conducted through DC bus bars inside the rack to the individual systems. Each resident half-depth, back-to-back mounted SGI Eco-Logical server or storage node is connected to the bus bars through blind cable mating, bringing DC power directly to each system and eliminating additional conversions inside the systems themselves. In order to maximize compatibility, AC networking gear can be easily supported in DC cabinets by splitting off an AC input circuit or by installing an inverter.

In rectified DC implementations, one or more rectifier shelves provide up to 92% power efficiency and a Mean Time Between Failure (MTBF) rating exceeding 1 million hours, and offer flexible levels of circuit-level power redundancy at the rack level. Each rectifier is capable of delivering 2700 watts with two powered off a single 208 volt AC circuit.

Each server and storage system is equipped with a high efficiency -48VDC power supply instead of a standard AC power supply. SGI DC power supplies achieve efficiency levels of up to 96.5% and MTBF ratings exceeding 2 million hours—a significant reliability increase over traditional AC power supply technologies.

By handling the AC-to-DC conversion within the rack instead of within each system, data centers can successfully shift thermal load associated with the conversion to the rack level. This reduced heat output and the use of higher MTBF power supplies alone can significantly increase overall system reliability and availability.

Central Rectifier Cabinet Option for Row-Level Rectification
For larger data centers deploying row by row of DC-based systems and seeking further data center optimizations SGI offers a Central Rectifier Cabinet solution. Ideal for rows of multiple populated SGI DC-based racks, this option eliminates the need for rectifiers inside each rack, instead housing them in a central location, known as the Central Rectifier Cabinet.

The Central Rectifier Rack houses up to 44 shelves with 176 rectifiers, delivering up to 475kW of DC power to multiple cabinets attached to the Rectifier Cabinet. DC bus bars in each server rack are connected directly to the Rectifier Cabinet for an efficient, constant delivery of redundant power. The Central Rectifier Rack is typically located in the center of a row and is configured with as many rectifiers as needed to power the row during periods of peak workload. Each rectifier is hot-swappable and can be replaced without the need for a scheduled maintenance period.