...
Horizontal scaling
Replicating resources
to
or
The number of instances is limitless
Vertical scaling
Adding more resources to a unit
to e.g. increasing the number of CPUs or RAM
But there is a limit to how much can be added
The OS may not be able to physically access the amount of RAM on the new configuration
...
And this cycle of wakamo continues
...
If you take the traditional approach to provisioning infrastructure,
The Cloud Solution
With the cloud model, you still need to do capacity planning, because there is a cost there. But unlike the model above as demand changes, AWS auto-scaling would bring servers in and out as demand changes. So the Capacity and Demand paths are in sync.