Understanding Scalability and Elasticity in Cloud Computing
There was a suggestion after our last AZ-900 class to use videos or visuals to better explain the concepts of scalability and elasticity as that might help people understand better, so I went searching online.
Over the past few days, I’ve done a deep dive into Scalability and Elasticity, exploring various resources to ensure we have a solid, yet simple, understanding of these concepts—especially for those preparing for the AZ-900 certification.
During my research, I consulted official cloud documentation, industry experts, and leading Azure educators such as Andrew Brown, John Savill, and Tim Warner. While there is some debate in the tech community about the precise boundaries between these terms, here’s what the majority of cloud resources agree on:
1. Scalability = Handling Increased Load
Scalability refers to a system’s ability to increase capacity to meet growing demand. This can happen in two ways:
🔹 Vertical Scaling (Scaling Up/Down) – Upgrading or downgrading a machine (e.g., increasing RAM, CPU).
🔹 Horizontal Scaling (Scaling Out/In) – Adding or removing multiple machines to distribute the load.
🔹 Example: If an app needs to handle more users, we can scale up by increasing server resources or scale out by adding more servers.
🔹 What Cloud Providers Emphasize: Most documentation from cloud providers describes scalability only in terms of increasing capacity (scale up/scale out). While true scalability includes the ability to scale down, this aspect is often overlooked—possibly because cloud providers benefit when users consume more resources.
2. Elasticity = Automatic Scaling (Up & Down)
Elasticity refers to a system’s ability to automatically increase or decrease resources based on real-time demand. It ensures that an application dynamically adjusts to load changes without manual intervention.
🔹 Example: An e-commerce website during Black Friday.
More users? The cloud automatically adds more servers.
Less traffic at night? The cloud automatically removes excess servers.
🔹 What Experts Say:
Tim Warner describes elasticity as “dynamic scaling.”
Andrew Brown calls it “automatically scaling.”
John Savill doesn’t use the term "elasticity" directly but talks about agility, which relates to rapid scaling.
3. Key Differences Between Scalability and Elasticity
| Feature | Scalability | Elasticity |
| Definition | Expanding capacity to handle more load | Automatically adjusting resources up & down based on demand |
| Type of Scaling | Manual or Automated | Always Automated |
| Primary Focus | Meeting long-term or planned demand | Responding to real-time fluctuations in demand |
| Example | Adding more VMs before expected traffic growth | Auto-scaling based on real-time website traffic |
4. Final Decision for the AZ-900 Class
I initially tried expanding beyond these definitions using personal experiences and real-world applications. However, I realized that for simplicity’s sake (since this is an AZ-900 class), it’s best to stick to the standard definitions used by major cloud providers and educators.
🔹 Scalability = The ability to increase capacity.
🔹 Elasticity = The ability to automatically scale up and down.
We’ll keep it simple and ensure everyone has a clear, exam-focused understanding before we dive deeper into real-world applications later on.
Stay curious, keep learning, and let’s build a strong cloud foundation together!
/Israel
VIDEOS
John Savill's video (16 mins) on YouTube where he talks about the benefits of cloud computing including scalability and "agility” Identify the Benefits of Cloud Computing - AZ-900 Certification Course
Tim Warner's video (10 mins) where he discusses cloud vocabulary including scalability and elasticity:Exam AZ-900 Microsoft Azure Fundamentals Online Study Guide Episode 2 - Cloud Computing Vocab
Andrew Brown's AZ-900 course (8 hours) on the FreeCodeCamp channel on YouTube: Microsoft Azure Fundamentals Certification Course (AZ-900) UPDATED – Pass the exam in 8 hours! (Start from around the 48:28 mark)