What Is Scalability?
Gartner describes scalability as “the measure of a system’s ability to increase or decrease in performance and cost in response to changes in application and system processing demands.” In simpler terms - it is the backbone of software that will allow the system to grow with your business. You can either scale-out, known as horizontal scaling, or scale-up, known as vertical scaling.
Horizontal scaling means you scale by adding more machines into your pool of resources. This could be through clustering - adding more servers to the cluster to increase the capacity. The advantage of horizontal scaling is it’s cost-effective but you need the architecture built for it. Horizontal scaling will be more fault-tolerant due to not having a singular point of failure. Prior to horizontally scaling, you need to understand the costs associated with licensing for additional servers and the additional costs of powering and cooling. You will also need to keep in mind that horizontal scaling will require maintenance and deployment by a Dev Ops team.
Whereas vertical scaling means you scale by adding more power to an existing machine (CPU, RAM). This can be through adding memory or an additional CPU. The disadvantages of vertical scaling are that it is typically costly and it does not make the system fault-tolerant (i.e. if your server goes down, your system will go down as well). The other disadvantage is that vertical scaling requires you to have downtime when the process is taking place. If you don’t have the flexibility to be down for any time period this is important to keep in mind.
Why Is Scalability Important?
Now the question is “why is scalability important to my situation?” Scalability isn’t a basic requirement of a program but it does link to the ability of the software to be flexible with growth and change with the market’s demand. Imagine you build an enterprise app for your mid-size company with 300 employees and within the next five years, your company doubles in employees to 600. Is your app going to be able to grow with your employment growth? Does it have the power to handle an additional 300 employees? As a consumer-facing software, does your software have the ability to shift as people’s tastes change and demand changes?
Benefits of Scalability
The benefits of focusing on scalability at the beginning of app development have both long-term and short-term benefits. Pursuing scalable software allows you to not only purchase what your company currently needs but also allows you to pay for what you need as you grow or as your needs change. It requires less money upfront considering you are not building your app out fully at the beginning. You will be adding functionality, user numbers, etc. as you grow.
Fallouts of Lack of Scalability
If you don’t think about scalability at the forefront it might not seem like a problem until the problem is too big to fix. Imagine if you created your app with your three hundred employees and the system can only take approximately 400 users. Once you hire more than 400, the system’s performance will start to drop until it cannot function correctly. Then your employees are finding ways to work around this slow app to get their jobs done and it may cause shadow IT. And if it’s a consumer-facing app you may lose customers due to the inefficiency of your app.
At the end of the day, it is important to know what your software or app is being used for and if you need to think about scalability. If you plan on your business growing and expanding it’s important to consider your ability to adapt to that growth and demand. Scalability is important to stay competitive, efficient, and keep up the quality of your software.