Scalability and Your IT Infrastructure Strategy: Horizontal vs Vertical Scalability

Organizations are more dependent upon their IT infrastructure than ever before as they continue to implement their digital transformation initiatives. Without the right resources in place to manage application workloads, it can be difficult to meet customer demand while simultaneously providing an outstanding user experience. When evaluating their infrastructure options, organizations must strike a careful balance between meeting their existing needs and ensuring that they can accommodate future goals.

In part one of this two-part series, we’ll take a closer look at the role of scalability in IT strategy and look at the technical benefits (and drawbacks) of the two primary models for scaling capacity. In part two, we’ll focus on how choosing the right infrastructure partner can help you maximize your growth potential while minimizing downtime, performance, and security risks.

What Is Scalability?

Scalability is a foundational computing concept that refers to an IT system or application’s ability to handle increasing workloads or demand without a significant decrease in performance or functionality. In other words, a system capable of scaling can adapt to changing demands without experiencing downtime, crashes, or other performance issues. Scalability can be achieved through a variety of means, but it is crucial in modern computing as businesses and organizations often require systems that can handle fluctuating workloads, data volumes, and users.

A straightforward example of scalability is an eCommerce business that experiences a surge in traffic during peak seasons, such as the weekend after Thanksgiving (including Black Friday and Cyber Monday). If its IT infrastructure is not scalable, the business may experience downtime or system crashes during peak demand, leading to lost sales, frustrated customers, and damage to its reputation. With scalable resources in place, however, the company can easily handle the increased traffic by provisioning additional processing and bandwidth to ensure its website and services remain responsive and available to customers. This can result in a positive customer experience, increased sales, and a stronger reputation for the business. As such, scalability is crucial for businesses to remain competitive and successful in the long run.

Why Scalability Matters

Having scalable infrastructure in place is crucial for a growing organization because it allows the business to adapt to changing needs, increasing workloads, and other demands without compromising performance or functionality. As a company grows, it needs more IT resources to support application workloads, data volumes, users, and other requirements. Without scalability, it could face performance issues, downtime, or other technical problems that can impact its productivity, revenue, and reputation. 

But scalability isn’t always about growth. Flexible infrastructure also provides the ability to scale down capacity when resources are no longer needed, which can help save money and reduce the costs associated with unused or unnecessary resources. This is especially true for businesses that operate on a pay-per-use model, where costs are directly linked to resource consumption. In addition to cost benefits, scaling down capacity is also important for security considerations. Unused or unnecessary resources can pose a security threat, especially if they are not properly maintained or secured. Scaling down capacity helps to minimize the potential attack surface and improve security posture.

What Is Horizontal Scalability?

Horizontal scaling, also known as scale-out architecture, is a method of scaling systems or applications by simply adding more resources (typically servers). This involves several technical steps to ensure that the new resources can be integrated with the existing infrastructure and work together to increase capacity.

When new assets are added to the infrastructure, they need to be provisioned and configured to work with the existing servers or nodes. This includes setting up the operating system, installing necessary software and applications, and configuring network settings to ensure that the new server or node can communicate with the existing infrastructure.

Once the new server or node is set up, it needs to be integrated with the existing infrastructure to distribute the workload. Load balancing techniques are typically used to manage workloads across multiple servers or nodes based on availability and capacity. The load balancer can be a hardware device or software application that distributes workloads according to predefined rules or dynamic algorithms.

To ensure that the new resources are being used effectively, applications and services must be designed to operate efficiently in a distributed environment. This requires developing them in a manner that enables the management of multiple instances running across different servers or nodes. Additionally, these applications and services must be capable of handling potential communication failures and network latency issues that may arise between equipment.

Advantages of Horizontal Scalability

Horizontal scaling strategies provide a number of benefits to organizations:

• Limited Disruption: Since horizontal scaling focuses on adding resources to infrastructure, there’s no need to take existing systems offline in order to upgrade capacity.
• Higher Availability: By distributing workloads across multiple servers or nodes, horizontal scaling can help ensure high availability and uptime, reducing the risk of mission critical applications going down and limiting access to data.
• Better Fault Tolerance: With multiple servers or nodes handling the workload, horizontal scaling can improve fault tolerance by automatically shifting the workload to other servers or nodes in the event of a failure.
• Flexibility: Horizontal scaling provides businesses with the flexibility to add or remove resources as needed, making it easier to adapt to changing business needs and demands.
• Better Performance: With multiple servers or nodes working together, horizontal scaling can improve performance by distributing the workload and reducing the load on individual resources.

Disadvantages of Horizontal Scalability

While horizontal scalability provides several benefits, it can also come with a few potential downsides:

• Added Complexity: Horizontal scaling can be more complex than vertical scaling as it requires managing multiple servers or nodes, coordinating workload distribution, and ensuring data consistency across the infrastructure.
• Increased Overhead: Adding more servers or nodes to the infrastructure can introduce overhead and increase maintenance and management costs, especially if the infrastructure is not properly designed or optimized.
• Network Latency: As the workload is distributed across multiple servers or nodes, network latency can be introduced, which can impact performance and user experience.
• Compatibility Issues: Applications or services that are not designed to work in a distributed environment may encounter compatibility issues when using horizontal scaling.
• Synchronization Issues: In a distributed environment, maintaining data consistency and synchronization can be a challenge, requiring additional measures to ensure that data is accurate and up-to-date across all servers or nodes.

What Is Vertical Scalability?

Vertical scaling, also known as scale-up architecture, is a method of scaling computer systems or applications by adding more resources to a single server or node. Vertical scaling works by upgrading the capabilities of existing hardware assets to handle more workload or perform more efficiently. 

There are a few common methods of scaling systems vertically:

• Increasing Processing Power: Upgrading the CPU, increasing the clock speed or the number of cores, or adding additional CPUs to the system can greatly enhance application performance and allow IT systems to handle greater processing workloads.
• Adding More Memory: Boosting available memory, typically accomplished by upgrading a server’s RAM or adding more memory modules, helps the system handle more data and run more tasks simultaneously.
• Increasing Storage Capacity: Upgrading the hard drive or adding more storage devices to the server will allow it to manage and access larger volumes of data, which may be critical for database-heavy workloads.

Once the resources are upgraded, the server or node needs to be reconfigured to ensure that the upgraded resources are properly integrated into the infrastructure. This can include updating the operating system, installing new software or applications, and configuring network settings to ensure that the upgraded asset can communicate with the existing equipment and applications.

Applications may need to be reconfigured to take advantage of the newly available computing resources. In some instances, the application code may need to be optimized.

Advantages of Vertical Scalability

Taking an upgrade-based vertical scaling approach can provide several benefits:

• Simplified Management: With only one server to manage, vertical scaling can be simpler and easier for IT teams to manage than horizontal scaling, especially when it comes to diagnosing and troubleshooting issues.
• Reduced Network Latency: By upgrading assets instead of adding new resources to the organization’s deployment, vertical scaling can reduce network latency, as there is no need to communicate between multiple servers or nodes.
• Improved Performance: Increasing a server’s processing power, memory, or storage can deliver faster response times and allow it to manage more workloads, which translates into better overall application performance and improved user experiences.
• Legacy Compatibility: Vertical scaling is often more compatible with legacy applications or services that are not designed to work in a distributed environment.
• Cost-Effective: Vertical scaling is often less expensive in the short term because it typically costs less to upgrade a server than it does to provision a new one.

Disadvantages of Vertical Scalability

While vertical scaling provides a number of immediate benefits, it also has a few potential drawbacks, especially over the long term:

• Limited Scalability: Vertical scaling is limited by the capacity of existing hardware resources, meaning that businesses can only upgrade them for so long and will eventually need to purchase more equipment to continue scaling
• Single Point of Failure: By focusing on upgrading a server or node, vertical scaling can introduce a single point of failure, making systems more vulnerable to downtime and data loss in the event of a failure.
• Upgrade Downtime: Upgrading a server or node can be a complex and time-consuming process involving multiple software and hardware changes. The server will need to be offline during this time, which can leave core business functions and data unavailable until the upgrades are completed.
• Longer Recovery Time: In the event of a failure, recovery time can be longer with vertical scaling, as assets need to be replaced rather than simply redistributing workload to other servers or nodes.
• Risk of Overprovisioning: Vertical scaling can lead to inefficient use of resources, as businesses may need to overprovision equipment to handle future or peak demand, resulting in underutilization during periods of lower demand.

Which Scalability Strategy Is Best for Your Workloads?

While horizontal and vertical scaling offer two distinct paths to increasing IT capacity, they don’t have to be mutually exclusive choices. That’s especially true now thanks to the availability of cloud computing platforms and colocation environments that offer tremendous flexibility when it comes to capacity planning and resource management.

In part two, we’ll look at how a hybrid IT strategy that incorporates data center colocation and cloud engineering allows organizations to leverage the benefits of both scalability models while minimizing (or even eliminating) the impact of their known disadvantages.

If you’re ready to explore your infrastructure options right away, talk to one of our experienced solutions engineers to learn how Evoque Data Center Solutions can put you on a path to sustainable IT growth.