Cloud Application Architectures

Cloud Scale

The cloud empowers you to alter your computing resources to meet your load requirements. You can alter your capacity both manually (by executing a command on a command line or through a web interface) and programmatically (through predefined changes in capacity or through software that automatically adjusts capacity to meet actual demand).

The ability to manually adjust capacity is a huge advantage over traditional computing. But the real power of scaling in the cloud lies in dynamic scaling.

Dynamic scaling

This term—which I sometimes also refer to as cloud scaling—enables software to adjust the resources in your infrastructure without your interactive involvement. Dynamic scaling can take the form of proactive scaling or reactive scaling.

Proactive scaling

This involves a schedule for altering your infrastructure based on projected demand. If you consider the application described back in Figure 7-1, we would configure our cloud management tools to run with a minimal infrastructure that supports our availability requirements during the early morning hours, add capacity in the late morning, drop back to the baseline until lunch, and so on. This strategy does not wait for demand to increase, but instead increases capacity based on a plan.

Reactive scaling

In this strategy, your infrastructure reacts to changes in demand by adding and removing capacity on its own accord. In the capacity valuation thought experiment, an environment engaging in reactive scaling might have automatically ...