Scalability In Cloud vs. Bare Metal Environments: A Comprehensive Comparison

In practical terms, scalability is the ability to right-size resources based on demand. There is hence a strong and direct link between effective scalability and effective resource management. With that in mind, here is a straightforward guide to cloud scalability vs bare metal scalability.

Understanding scalability

At a basic level, scalability effectively means the ability to add and remove resources. There are, however, two basic strategies for doing so. These are known as vertical and horizontal scalability.

Vertical scalability, also known as scaling up, involves adding more power (CPU, RAM, storage) to an existing server or machine. For example, it could mean upgrading a server’s RAM from 32GB to 64GB or increasing the CPU cores from 4 to 8.

Horizontal scalability, or scaling out, involves adding more machines or servers to a system to distribute the load. For example, it could mean adding extra web servers to a load balancer to handle increased web traffic.

Assessing scalability

Cloud scalability vs bare metal scalability can be assessed by looking at three key performance indicators. These are the ease with which resources can be scaled, costs, and the impact on performance and availability.

Ease of scaling resources

Public cloud services are easier to scale than bare metal servers. This is true of both vertical and horizontal scaling.

Vertical scalability

Public cloud services offer a seamless approach to vertical scalability. Users can easily upgrade their virtual machines (VMs) with more CPU, RAM, or storage through a user-friendly interface or API calls.

This process is typically instantaneous or requires minimal downtime, thanks to the cloud providers’ extensive infrastructure. For example, platforms like AWS and Azure allow for quick resizing of instances, ensuring that applications can scale up to meet increasing demands without significant delays.

Vertical scalability on bare metal servers is less flexible and often involves significant downtime. Scaling up requires physically upgrading hardware components such as CPUs, RAM, or storage. This process is time-consuming, requiring careful planning, procurement of hardware, and manual installation, which can disrupt ongoing operations.

Horizontal scalability

Horizontal scalability in public cloud services is highly efficient and automated. Cloud platforms provide tools like load balancers and autoscaling groups that automatically add or remove instances based on the current load.

This ensures optimal performance and cost-efficiency by dynamically adjusting resources. Services like AWS Auto Scaling and Azure VM Scale Sets simplify the management of large-scale distributed systems, enabling effortless scaling out to handle spikes in traffic or workloads.

Horizontal scalability in bare metal environments is also more complex compared to cloud services. Adding more servers involves purchasing, configuring, and integrating new hardware into the existing infrastructure.

This requires manual intervention and substantial lead time, which can delay the scaling process. Additionally, setting up load balancers and ensuring seamless integration of new servers often demands skilled personnel and extensive testing.

Costs

With the public cloud, there are minimal to no upfront costs for scaling up. Clients simply pay for the extra resources they use. If the scaling is expected to be short-term, it will probably be charged on a pay-as-you-go pricing model. If it’s expected to be longer term, it will probably be charged on a subscription pricing model (or a combination of subscription and on-demand pricing).

With bare metal servers, scaling up either vertically or horizontally typically involves significant upfront costs. Vertical scalability tends to be the more economical option as it typically involves just upgrading specific components. Horizontal scaling involves adding whole new servers. Both options require paying for physical installation and may generate extra management overheads that lead to further costs.

Once that cost is absorbed, however, the running costs of bare metal servers tend to be meaningfully lower than the running costs of cloud services. This is particularly true when businesses use on-demand pricing but also holds for subscription-based pricing.

On the flip side, however, scaling down a cloud service just requires canceling the resource. With bare metal servers, components or whole servers have to be physically removed. This raises the question of what to do with the resources that are no longer needed.

Impact on performance and availability

Public cloud services offer flexible and rapid scaling through virtualized resources, but performance can fluctuate due to shared infrastructure, potentially leading to “noisy neighbor” issues. Dedicated instances are available for consistent performance at a higher cost. Advanced load balancing and optimization tools help maintain performance during scaling.

Cloud services ensure high availability with features like automatic failover, data redundancy, and multi-region deployments. Scaling operations are seamless and automated, minimizing downtime. Extensive data center networks and robust disaster recovery mechanisms enable quick resource adjustments and constant service availability.

Scaling bare metal servers involves adding or removing hardware so that the servers maintain a consistent level of performance as their workload changes. The fact that there is no virtualization overhead means that bare metal servers use resources more efficiently than cloud services.

Scaling bare metal servers can impact availability due to the time needed for hardware procurement and installation, potentially causing downtime. High availability requires significant investment in redundancy and failover solutions, which are less seamless than equivalent cloud options.