Microsoft has teamed up with computer scientists from Carnegie Mellon University and the University of Washington on an initiative aimed at limiting the environmental impact of the hardware used in servers. The program, called GreenSKU, uses memory and storage drives from retired servers and gives them a second life through software tricks.

Ashkitha Sriraman, a computer science professor at Carnegie Mellon University who is involved in the program, pointed out that it is not uncommon for an entire server to be scrapped if only one component fails or becomes inefficient.

The GreenSKU program is designed to identify salvageable RAM and SSDs and reuse them in refurbished servers. ComputeExpressLink (CXL) controllers allow the use of DDR4 or DDR5 and are critical in helping retrofit servers.

The team utilized a pooling technique called the Pond method to handle older memory with higher latency and lower bandwidth, and RAID striping to handle slower SSDs. In addition, specialized software is deployed to identify tasks best suited to run on GreenSKU.

Microsoft replaces its Azure servers on average every three to five years, regardless of whether they are still functioning properly.

The refurbished machines use AMD Bergamo processors, which were selected for their energy efficiency. Unfortunately, there is no fix for their lack of cache performance compared to the latest chips used in Azure servers. Of course, not every application requires state-of-the-art performance.

"There are a lot of applications that run very well on refurbished machines," Sriraman said.

At current rates, the information and communications technology (ICT) industry will account for more than a third of total global emissions by 2050, according to the Association for Computing Machinery's Technology Policy Committee. The team believes that if scaled up, their reuse technology could reduce global carbon emissions by 0.1% to 0.2%. That may not sound like much in percentage terms, but as Sriraman points out, it's a huge number, equivalent to the entire emissions from smartphone use in the United States.