Facebook data center engineering’s Jay Park posts on what Facebook presented at SVLG Data Center Efficiency Summit.
Optimizing Data Center Energy Usage
by Jay Park on Wednesday, October 20, 2010 at 8:32am
When it comes to optimizing data centers for energy usage, the minutest changes can have significant impact. Facebook’s growth over the years has expanded our data center footprint greatly, and we've learned many lessons and applied some of the industry’s best practices to make our data centers much more efficient, saving us money and using less energy. At the Silicon Valley Leadership Group's Data Center Efficiency Summit last week, we shared these lessons and the new strategies we've implemented with the data center community at large so they too can utilize these techniques, multiplying the energy savings and environmental protection across the infrastructure of many other companies.
Based on this graph
A 9% improvement in IT load for a 276 KW savings means the IT critical capacity was 3 megawatts. Assuming low power servers with around 6,000 servers per megawatt, the servers in the environment are 18,000.
Jay discussed saving 3 watts per server.
We discovered that the server fans were spinning faster than necessary, so we worked with the server manufacturers to optimize their fan speed control algorithm while keeping temperatures within the recommended range. For each server, this saves up to 3 watts and requires less air (up to 8 cubic feet per minute), which quickly adds up in a 56,000 square foot facility.
3 watts per server is 54,000 watts. With 56,000 sq ft and 3 MW of power, the power is only 50 watts per sq ft which fits with this low density image below. Note the amount of open space.
The inlet temperature is not mentioned in the post, but I recall that Jay said 68 to 72 degrees which fits with the raise in return temperature.
In the end, we raised the temperature for each CRAH unit's return air to 81 degrees Fahrenheit from 72 degrees Fahrenheit.
The group I was sitting with during Facebook’s presentation wasn’t overly impressed, but with 50 watts sq, ft, 3 megawatt IT load, leasing a facility (not owning), the Facebook engineering group most likely had a very short ROI payback, and wanted to keep their capital investment to a minimum.