Organizations adopt the cloud for business reasons, and the exam expects you to match each benefit to a situation. Most questions describe a problem, such as a traffic spike, slow projects or outages, and ask which benefit or approach solves it.
Scalability is the ability to handle more work by adding resources. You can scale up (vertically) by moving to a bigger machine, or scale out (horizontally) by adding more machines. Elasticity is scalability that happens automatically and in both directions: resources are added when demand rises and removed when it falls, so you do not pay for idle capacity. A shop with a holiday peak benefits from elasticity; a company growing steadily year after year benefits from scalability.
Agility is the speed at which a business can try new ideas and respond to change. In the cloud a team can create an environment in minutes, test an idea and delete everything if it fails. That lowers the cost of failure and encourages experimentation. Managed services add to agility because teams spend less time on patching, backups and hardware, and more on features customers see.
Reliability means a service keeps working when parts fail. Cloud providers offer many data centers grouped into zones and regions, and managed services that replicate data automatically. Designing across zones and regions lets an application survive failures that would take down a single on-premises server room. Flexibility is related: you can choose from many types of compute, storage and pricing to match each workload.
Strategic value is the bigger picture. By moving undifferentiated work, such as running data centers, to a provider, a company can focus its people and money on what makes it different. It also gains access to capabilities it could not easily build, such as large-scale analytics, AI and global networks. Cost matters too, but the exam often treats cost savings as one benefit among several rather than the main reason.
Key terms
- Scalability
- The ability to increase capacity to handle more load, by scaling up or out.
- Elasticity
- Automatically adding and removing resources as demand changes, so capacity follows load.
- Agility
- The ability to move quickly: provision, experiment and change direction with little delay or cost.
- Reliability
- The ability of a service to keep working correctly when components fail.
A tax-preparation website is quiet for ten months and extremely busy before the filing deadline. With autoscaling on Google Cloud it runs a few instances most of the year and hundreds in the final weeks, paying for the peak only while it lasts.
Check yourself
A startup wants to test a new product cheaply and drop it quickly if it fails. Which benefit is this?
Agility: resources can be created and removed quickly with no up-front purchase.
What is the difference between scaling up and scaling out?
Scaling up moves to a larger machine; scaling out adds more machines that share the load.