Scaling Up: Understanding the Differences Between Horizontal Vs Vertical Scaling

Knowing the difference between horizontal vs vertical scaling is crucial for making the most effective decision for your needs. Almost every business that experiences constant growth over time comes to a point where it needs to scale up its resources to meet demand. And when this happens, your data center company will usually present you with two options: horizontal vs. vertical scaling.

So, now, you’re met with the following dilemma – which one should you go for? No matter if you choose horizontal or vertical, both will allow you to boost the resources you have on your system. However, the two options still differ in other ways, and knowing how they differ can help you choose the ideal one when the time comes.

In this article, we’ll cover both options in great detail so you can understand their differences. Also, it’ll provide you with a comprehensive guide on which option is best at what time and more.

What Is Scalability and How Does It Work?

Scalability shows if a system or computer functions properly when faced with changes in size and volume. Let’s explain it further with an example.

Say you have a website. Your website has been growing exponentially, but you’ve been able to handle the increased demand with no need for additional resources up until now. However, the growth has reached a point where it needs to be supported with more RAM, bandwidth, storage, etc.

Suppose you’re able to get more of those resources without any hassle or disruptions in service quality. In that case, your web hosting or server is considered to be highly scalable, as it can meet increased demand quickly and easily.

Thus, scalability shows a system’s ability to handle more – more traffic, more demand, more growth, etc.
However, there is another side to scalability. Namely, it also refers to scaling down – needing fewer resources than you already have.

For example, if you have a seasonal website and you enter your off-season, you won’t need as many resources as you would when the business is at its prime. So, you can get rid of some resources by scaling down.

Scaling up and down are integral parts of the definition of scalability, since scalability, at its core, involves systems’ ability to adapt to change. And there are two options you can use to implement scaling, which we will explain next.

Horizontal Scaling

Horizontal scaling (also called scale-out) is the process of adding more servers, machines, or nodes to your network’s infrastructure to the new, increased demand. Let’s take hosting a website on a server as an example.

In that case, if you use this option, you’ll add another server to meet the growing demand for your website. Now, you’ll use both servers to get the resources you need to handle the growth of your website.

Benefits of using horizontal scaling:

  • This option has no limits, so you can add as many servers or machines as your budget and data center allows.
  • It decreases risk because if one server fails, the other one will keep your system online.
  • When you scale your resources, your system or website won’t go down – it will remain active.
  • This is also suitable for scaling down and allows you to only pay for the resources you need.
  • It is easy to upgrade.

Drawbacks of using horizontal scaling:

  • You need to have technical knowledge and skills to set up and maintain more machines.
  • Usually, there are expensive licensing fees that you need to pay.
  • You’ll have to buy more hardware, like routers, switches, etc.
  • The more nodes or machines you add to your infrastructure, the more complicated its maintenance will be.
Horizontal Scaling Example

Vertical Scaling

Vertical scaling (also called scale-up) involves adding more resources to your current system. So, you’ll upgrade your old server instead of getting a new one.

Let’s use the previous example of hosting a website to explain this better. So, as your website grows, it needs more resources. With this option, you’ll add more RAM, storage, etc., to the server you’re currently using to meet demand. On the other hand, with horizontal scaling, you would get a whole new server.

So, here, you can add more CPU cores and any other resource you need to handle more website traffic and growth. That’s why this is also called scaling up because you’re boosting your current system instead of getting a new one.

There are also times when your server is maxed out and can’t handle more resources. In that case, you replace the server with a new one. So, again, you’ll be using one machine instead of two, as you would with horizontal scaling.


  • Faster option.
  • It costs less compared to buying new machines.
  • You won’t need to free up space in your data center, resulting in lower power and cooling bills.
  • Since everything runs on one machine, data consistency and integrity are better.
  • Easy to use and implement.
  • It won’t make managing and maintaining your infrastructure harder.


  • It isn’t suitable for unlimited growth because every machine has resource limits.
  • Server downtime is more likely.
  • You have to be offline to upgrade your resources.
  • Data loss is more likely because all your data will be on the same machine.
Vertical Scaling Example

Horizontal vs. Vertical Scaling (Key Difference)

Now that we’ve covered the two options you can use to scale your resources, let’s take a look at how they differ.

FeaturesScale-Out (Horizontal)Scale-Up (Vertical)
ImplementationAdding new servers or machines to your existing network.Upgrading your current server or machine.
 Difficult because it requires technical skills.Easy because you’ll only need to add more resources.
CostHigh. You’ll need to buy a new machine every time you scale.Low and high. This depends on how many resources you want to add.
Single point of failureEase-of-useNo, because you’ll store your data on more than one machine.Yes, because you’ll store your data on one machine.
StorageYour data lives on multiple machines and nodes.Your data lives on one machine.
ConsistencyYou might experience issues because your data will move between different machines.Better consistency because everything is on one server.
LimitsNo limits except for your budget.It has limits because machines can only handle a certain amount of resources.
Downtime when you scale No, because you won’t have to turn off your server to scale.Yes, because you need to turn off your server to add more resources to it.
Unused resourcesNone, because you can easily scale down.Yes, because you’d have to physically take out the new RAM, SSD, etc., to lower your resources.
Scale-down optionsYesYes. However, you have to take out the hardware manually to scale down.
ExamplesMongoDB, Cassandra, Google Cloud SpannerAmazon RDS and MySQL


Which Is Better Horizontal Or Vertical Scaling?: Which Should You Choose and When?

When deciding which option you should choose between horizontal vs. vertical scaling, you should consider a few factors. That way, you’ll make the right decision right off the bat.

The first factor you should consider is performance. If you need better performance and a lot of resources, horizontal is the better option. On the other hand, if you only need a slight boost in performance, vertical is better.

Another important factor is flexibility. For example, if you plan on expanding and growing significantly in the future, horizontal is the better option for you. That’s because it allows you to add an unlimited number of resources. If you only scale to meet increased demand, vertical is more than enough.

The next factor you should consider is how often you perform upgrades. If you have many software programs and apps on your system, you’ll need to upgrade them frequently. In that case, horizontal is better for you. That’s because, with horizontal, you won’t have to shut down your server to perform upgrades.

Lastly, you must always ensure that your chosen option fits your budget. Namely, if you have a tighter budget, vertical is better. On the other hand, horizontal is the way to go if you have a broader budget.

Horizontal Vs Vertical Scaling Graphic


Understanding the difference between the two scaling options is critical for businesses. Namely, it enables them to choose the option that suits them best and ensures that their growth will be uninterrupted by technical difficulties. 

In the horizontal vs. vertical growth debate, the most important thing to remember is that the former allows unlimited growth, while the latter is better for slower, more controlled website growth. However, whatever you do, make sure you find a provider that offers both horizontal and vertical scalability. 

Here at Colo Solutions, you’ll get access to both options and will be able to pick the one you like best. Also, even if you choose one and change your mind later, we will help you seamlessly transition from one scaling option to another. Contact us today to learn more.


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