As you might know, your app or system can handle a set number of simultaneous requests. If the demand exceeds this number, it won't be able to process further. When this happens, it's time for scaling! Scalability relates to how your system grows and adapts to change. If you find it's time to do this, you can choose between vertical and horizontal scaling. In this article, we'll cover the latter of the two: horizontal scalability. We'll explain what it entails, how it compares to vertical scalability, and when to use it. Let's dive in!
What is Horizontal Scalability?
Horizontal scalability entails adding nodes, computers, or database server racks to a system. Also called scaling out, it helps cope with new demands. As a result, several resources share the workload. Horizontal scalability allows for dealing with growing demands and adds complexity to your operation. Below, we'll look at the pros and cons of this type of scaling.
Benefits of Horizontal Scalability
More Resiliency
Several systems or database servers mean there is no single point of failure. Hence, horizontally scaled systems have good resistance to malfunction of a single instance. And, as data distributes across all nodes, the risk of losing any of it minimizes.
Easier Scaling
Regarding hardware, horizontal scalability simplifies the scaling process. Why? Well, you only need to add new machines to your current set. There is no need to check system requirements for upgrades on your existing devices.
Less Downtime
When adding machines, switching off the existing ones is unnecessary when scaling. This procedure reduces or even cuts to zero downtime. Thus, upgrading processes are less likely to affect clients.
Better Performance
Horizontal scaling entails several machines sharing the traffic node. With it, you can have more endpoints for connections. This method results in better network performance and security.
Disadvantages of Horizontal Scalability
Complex Maintenance
Maintaining one server or machine is more accessible than maintaining several. Also, horizontal scalability requires load balancing and potentially virtualization software.
Higher Initial Costs
The initial cost of horizontal scalability is higher. The reason is that it involves buying new database servers or machines. Updating them through vertical scaling is more cost-effective.
Horizontal Scalability vs. Vertical Scalability
We know what horizontal scalability is. Now it's time to meet its counterpart: vertical scalability—or scaling up. This method entails adding more resources or power to the same node, computer, or server. You can scale your memory, processing speed, or storage. Further examples of it are MongoDB, Cassandra, and Google Cloud Spanner. So, what else sets these two scaling methods apart? Let's look at their main differences.
| Horizontal Scalability |
Vertical Scalability |
| It entails splitting databases by adding new servers or machines |
It involves adding new resources with data remaining in a single node |
| Uupgrading is easier as you only need to add new appliances |
It’s harder to upgrade, and limitations on how much you can upgrade |
| As it requires load balancing, it's challenging to install and maintain |
It’s easy to implement and maintain as it entails a single system |
| It’s costly as it involves several machines across many data centers |
Since it involves just one device, it’s more cost-effective. |
| Horizontal scaling needs more time to implement |
Vertical scaling requires less time to implement |
| Great for increasing geographical range |
It can only offer a limited geographical presence |
| There is a lower probability of downtime |
It involves significant downtime rates |
| There is no limit to how many machines you can add to the system |
Scaling is limited, as a single device has a set capacity |
Both horizontal and vertical scaling have their pros and cons. Which one you choose will depend on your resources and your needs. Below, we'll share when it's best to choose one.
When to Use Horizontal Scalability?
● When dealing with multiple users, it will prevent crashes
● When you want to increase performance.
● When you want to simplify the upgrading process.
● When you have a more generous budget.
● When you want built-in redundancy.
When to Use Vertical Scalability?
● When you're on a tight budget.
● When you require unique data consistency.
● When a single machine can meet your scaling requirements.
Bonus: On-Premise vs. Cloud Scaling
There are alternatives beyond vertical and horizontal scalability! You can choose between on-premise and cloud scaling. Nowadays, cloud environments are becoming more and more common. So, they have gained a lot of ground on on-premise infrastructure. Horizontal scalability tends to be more popular when it comes to on-premise-based servers. Yet, vertical scalability is also possible in this case. In this context, cloud scaling can take place on horizontal and vertical scaling. Regardless of your choice, cloud scaling has the extra benefit of automatic scaling. This feature comes beyond its manual and scheduled scaling. Hence, it can be a great way to save both time and money, making the scaling process more straightforward.
Conclusion
Scalability is an indispensable aspect of any growing business. If you want to scale up your app or system, horizontal scalability is a great way. It simplifies the scaling process, improves performance, and decreases downtime. We hope this article has given you all the information you need to make the right choice.
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