The cloud is essentially a metaphor for a network of computers in which computational tasks and resources can be shared.
The big idea here is that users simply rent the computing power, the storage or an application for as long as they need it without having to invest in the infrastructure behind it.
That makes computing cheaper, easier and more efficient.
There are well known problems of course. The most obvious relates to guaranteeing the security of data when it is stored on computers that that a user does not own and that many others can also access. But various solutions have emerged such as encrypting data before it is sent to the cloud. For that reason, the migration to the cloud is proceeding at full speed in many places.
That may be folly. Today, Bryan Ford at Yale University in New Haven says that the full risks of this migration have yet to be properly explored. He points out that complex systems can fail in many unexpected ways and outlines various simple scenarios in which a cloud could come unstuck.
In the worst case scenario, a cloud could experience a full meltdown that could seriously threaten any business that relies on it.
Ford identifies a number of different possibilities. One example involves an application provider who bases its services in the cloud, such as a cloud -based advertising service.
He imagines a simple scenario in which the cloud operator distributes the service between two virtual servers, using a power balancing program to switch the load from one server to the other as conditions demand.
However, the application provider may also have a load balancing program that distributes the customer load.
Now Ford imagines the scenario in which both load balancing programs operate with the same refresh period, say once a minute. When these periods coincide, the control loops start sending the load back and forth between the virtual servers in a positive feedback loop.
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