Scalability—the ability to modify the capabilities of your infrastructure to meet your changing application requirements—is one of the most compelling benefits that attracts customers to the cloud.
Scaling on-premises resources usually requires that you adequately plan for any future scenario well in advance. You need to analyse existing infrastructure or applications requirements, then forecast for future growth. Deploying the infrastructure, planning connectivity, addressing security along with all required components can be complicated—and take months to deliver. The challenges and limitations of this approach are some of the main reasons driving customers to the cloud. Add to that, the Capex model and the processes around it are no longer acceptable to the business as organizations prefer to have the infrastructure they need, immediately—plus the ability to pay only for the resources used.
The cloud offers customers agility and scalability to meet their business requirements without paying for resources that aren’t required. You can pay only for what you need or use—and that’s it. Plus, in the cloud, customers are equipped to scale out their infrastructure vertically or horizontally to meet their demand.
Vertical Scalability is when a virtual machine (VM) is adjusted to meet the projected demand; e.g., changing a VM from a smaller instance to a larger instance, thereby increasing the compute, RAM, and I/O to meet demand (scaling up). In this example, the application running on the VM remains unchanged, but the application has more resources to utilize. This is best suitable for monolithic/legacy applications. Vertical scaling can be achieved on-premises today, but the time it takes to deliver the infrastructure poses the challenge. Likewise, physical infrastructure and virtualization platforms can be scaled on-premises, yet the process can take months—while scaling up and down in the cloud can be achieved in minutes.
With vertical scaling you are restricted by the size of the physical host (i.e., the underlying platform). You cannot scale up more than the resources that exist on a host. If the demands of your workload surpass the resources available from the underlying infrastructure, you’ll need to explore other scalability options.