In 2018, Microsoft sank 864 servers 117 feet beneath the North Sea to cool them naturally; two years later, their failure rate was one-eighth that of land-based machines

Microsoft lowered a sealed cylindrical data center that contained 864 servers into the North Sea off Scotland's Orkney Islands in 2018. The 40-foot-long vessel was placed about 117 feet below the surface as part of Project Natick, which was an experiment designed to test whether data centers could operate reliably on the seabed while using seawater as part of the cooling system.When Microsoft retrieved the vessel in 2020, the company found that the servers inside had experienced a failure rate one-eighth that of its land-based comparison group. Microsoft's own Project Natick results describe the reliability difference as one of the main findings from the experiment.A data center inside a steel vesselThe Northern Isles module contained 12 server racks that held 864 servers. InformationWeek reported that the cylindrical vessel was approximately 40 feet long and 10 feet wide and was installed at a depth of 117 feet. The sealed vessel was filled with nitrogen rather than ordinary air, which created an environment with less oxygen and therefore less potential for corrosion inside the enclosure.Cooling was one of the central engineering reasons for putting the equipment underwater. The system transferred heat to the surrounding seawater instead of relying on the same cooling infrastructure used by a conventional land-based facility, and the vessel was connected to land by cables that supplied power and provided the network connection. It was designed to operate without technicians entering the module to carry out routine maintenance.Two years without routine maintenanceMicrosoft retrieved the Northern Isles module in July 2020 and compared the performance of its servers with a group of land-based machines. The underwater servers had a failure rate one-eighth that of the land-based control group, to which Microsoft said the result suggested that the controlled environment inside the vessel had produced more reliable operation than conventional conditions.Microsoft's researchers proposed two main explanations for the difference, firstly, the nitrogen atmosphere inside the vessel was less corrosive than an oxygen-rich atmosphere, and secondly, the absence of people working around the equipment eliminated some of the physical disturbance that servers experience in conventional data centers. Microsoft's Project Natick research page says the company believed those factors were responsible for much of the reliability difference, although it also described the explanation as a hypothesis requiring further analysis.The project therefore tested whether a sealed data center could operate for long periods without the normal human access associated with land-based facilities. The experiment also used ordinary commercial server hardware rather than equipment created specifically for an underwater installation.The experiment ended with retrievalMicrosoft brought the vessel back to the surface and examined the equipment after two years on the seabed. The company reported that the underwater servers had performed more reliably than the land-based control group. InformationWeek reported that the vessel contained 864 servers and that the unit was retrieved after two years, and also noted that the servers had been installed in 12 racks and that the cooling system used cold seawater to remove heat from the equipment.Project Natick was a research program examining whether subsea facilities could be deployed close to coastal population centers, where demand for data services is concentrated. Microsoft also used the module's computing capacity for research during the COVID-19 pandemic, and its Project Natick results say the system supported Folding@home and World Community Grid after the pandemic began.The company ultimately removed the hardware and planned to recycle the pressure vessel and other components, and Microsoft's current project page says the seabed is being restored to the condition it was in before deployment.Catch the latest World News and Live updates. Download the TOI app.