Google had to shut down its London data centre during the recent heatwave to avoid further downtime as its cooling systems failed, according to its incident report.
The report doesn't explain why the cooling systems failed but it does say Google first became aware of issues affecting two cooling systems on Tuesday, 19 July.
On that day, the UK experienced record temperatures of 40 degrees in some parts of the country with London reaching 39 degrees in the afternoon. The level of heat caused significant damage across the country with delays to transport services due to infrastructure melting or buckling.
Data centres are largely designed for the areas they reside but the temperatures on 19 July were unexpectedly high and it appears that the data centre was not prepared. Google said its engineers worked on mitigations to the failed cooling system during the day but their efforts failed. And, as London's temperature remained above 35 degrees well into the evening, the engineers decided to power down that zone at 6PM UK time to prevent any more outage or damage to the machines.
"One of the data centres that hosts zone Europe-west2-a could not maintain a safe operating temperature due to a simultaneous failure of multiple, redundant cooling systems combined with the extraordinarily high outside temperatures," the Google incident report states.
From there, several services were largely unavailable across the Europe West 2 zone. These included all virtual machines running on Google's Compute Engine, which is estimated to be 35% of all the VMs in the region.
The tech giant's engineers did manage to revive the cooling systems at around 10PM, despite temperatures still lingering at unusually high levels. As to the reason behind the failure, Google's report said it was still "conducting a detailed analysis".
