One of the great things about cloud computing is that you don’t have to worry about bumpy old software updates, except when they take down the entire cloud.
That’s what happened on Tuesday when Microsoft’s Hotmail, Outlook.com, and Skydrive sites went down for some.
On Thursday, Microsoft explained what happened, and as near as we can tell, the problem was a software glitch — in an update to the data center’s air conditioning system. Microsoft says that things went wrong when it installed new firmware “on a core part of our physical plant,” which caused the entire data center to overheat.
Translation: Microsoft was probably updating its heating, ventilation, and air conditioning system, called an HVAC system by operations people, when things went wrong. Without air conditioning, the heat from thousands of servers would make it too hot to operate a computer in the data center. We asked Microsoft to clarify what core part of the physical plant went down, and which data center was hit, but they wouldn’t tell us.