Multi-cloud vs. hybrid cloud: What's the difference and why it matters

The difference between a multi-cloud and hybrid cloud

To some extent the hybrid cloud vs. multi-cloud discussion is semantics, and, in many cases, you can safely interchange the two terms. But a hybrid cloud usually includes a combination of public and on-premises or hosted private clouds.

A multi-cloud, on the other hand, makes no distinction between the kinds of clouds that you operate. Perhaps your multi-cloud doesn't have a private cloud at all, and you operate everything on AWS and Microsoft Azure with a little bit of G Suite thrown in. That's a multi-cloud environment. Ta-da!

There's another difference to be aware of when looking at multi-cloud vs. hybrid cloud. The individual clouds in a multi-cloud setup may not be integrated with one another. That's part of the reason for the plurality in multi-cloud as opposed to the singularity of hybrid cloud. In a hybrid cloud environment, one of the sometimes incorrect assumptions is that the cloud components are integrated to form the cohesive singular entity. That's often the case, but not always.

Cloud evolution

The way people think about the cloud has changed dramatically in the last decade. Similarly, the terms used to describe cloud computing have evolved as well.

• With a private cloud, everything is inside an organization's data center. Services have their own sandboxes, and application design is monolithic.
• A public cloud is external to the data center. It's service- and app-centric with lines between each app. Cloud-native applications are more modular, but people still treat the environment as a data center rather than changing their thinking.
• A hybrid cloud is a bit of both. Each side -- the private cloud and the public cloud -- is separate, but they form a greater whole. It's still app-centric for the most part, but there's a greater level of infrastructure integration. It also has the beginnings of distributed application support.
• With multi-cloud, applications can span a number of clouds, but they don't have to. Components of an application live wherever it makes sense. People don't see data centers anymore, but they view the multi-cloud as a massive fabric that binds together application components.

These descriptions are intended to show a progression. They aren't necessarily a comprehensive outline of all types of cloud architectures.

Multi-cloud vs. hybrid cloud: The upsides

A hybrid cloud provides an organization with the flexibility to avoid vendor lock-in and use services from and deploy workloads to both on-premises private clouds and public clouds. For instance, it can deploy a mission-critical workload with significant security requirements to the private cloud, where the business retains control over both the infrastructure and software stack. Other workloads, such as web servers and test environments, may be deployed to one or more public clouds. This frees the organization from having to invest in a full private cloud infrastructure for every workload, and lets it pay only for the resources it uses for the workloads that it deploys to a public cloud.

In addition, a hybrid cloud lets an enterprise take advantage of the scalability that the public cloud offers to perform functions such as process infrequent -- but intensive -- big data analytics that involves creating a large Hadoop cluster. Hybrid clouds also enable businesses to share resources among more than one cloud. They can use a private cloud to run a workload even while the data associated with that workload is stored in the public cloud. They can also migrate a workload between public and private clouds to take advantage of fluctuating resource costs and different levels of network traffic.

With multi-cloud, the world becomes your playground. You get the most comprehensive mix of public and private clouds, and you don't necessarily need to deeply integrate the different clouds you use. Of course, depending on how you use such services, you may want to integrate them. But it isn't required by definition in a multi-cloud. For example, you may want to deploy different parts of a distributed application in multiple clouds in order to protect against the failure of one. So if a natural disaster or a manmade incident causes an outage in one provider's cloud, you will have one or more alternatives to fall back on.

With multi-cloud, the world becomes your playground. You get the most comprehensive mix of public and private clouds, and you don't necessarily need to deeply integrate the different clouds you use.

A multi-cloud approach also provides organizations and application developers with the ability to pick and choose the discrete components that will comprise their applications and workloads. There are no more technical barriers to leap over, and developers can select specific services that meet their needs rather than settling for what a single provider offers. The multi-cloud approach lets developers and IT admins choose a best-of-breed service from one cloud provider to handle specific requirements, while turning to other providers for other services where those providers have strong offerings.

The downsides of hybrid and multi-cloud options

For all the upsides of both approaches in the multi-cloud vs. hybrid cloud debate, there are also downsides. Hybrid clouds can be complex to implement and maintain. Deploying the private cloud piece of the hybrid setup can be challenging in itself. It requires an extensive infrastructure commitment and significant staff expertise. On top of that, to be considered a hybrid model, the private cloud must be integrated with at least one public cloud to the extent that the underlying software stacks work together. As the private cloud is integrated with multiple public clouds, it becomes even more complex and challenging to deal with.

Hybrid clouds also present their own management, security and orchestration challenges. To maintain a reasonable level of efficiency, most businesses will want to integrate both sides of the cloud as deeply as possible. This requires a hybrid approach that enables federated and consistent identity management and authentication processes.

Depending on the service you're integrating, you may also need to worry about other potential vulnerabilities, such as securing API traffic exchanges. On the orchestration side, a hybrid cloud might require an intelligent workload deployment tool that's able to determine deployment targets based on costs, security, traffic, the availability of public clouds and other relevant criteria.

Multi-cloud has its own set of issues as well. Using a multi-cloud setup opens a floodgate of security concerns. The more clouds you consume, the bigger the security challenge. Remember, in security, the attack surface is the potential impact that hackers are aiming for. The more cloud services you add to your multi-cloud environment, the bigger the attack surface becomes, and the more opportunity you provide for a bad guy to find an opening to exploit.

Also, costs can spiral out of control with multi-cloud if you're not constantly monitoring them. Skyrocketing cloud bills often take people by surprise. Using multiple clouds makes that situation even worse. A poorly constructed database query that eats up CPU cycles in one of your cloud locations can wreak havoc on your budget.

Finally, there's the issue of governance. The right governance and oversight can counter many of the downsides, but a lot of organizations do governance poorly, and some developers still equate governance with command and control efforts. Nothing could be further from the truth, however. Governance is the creation of a foundation for future success. Command and control, on the other hand, creates a scenario ripe for long-term mediocrity if driven by the wrong people. Good governance will help developers and the organization focus more effectively on outcomes that are positive for the business and don't come with unacceptable levels of risk.

Multi-cloud vs. hybrid cloud architectures

There are similarities between multi-cloud and hybrid cloud models, but they also have some fundamental differences. As previously mentioned, a hybrid cloud is a mix of private -- either on premises or hosted -- and public clouds that are tightly integrated, with orchestration providing a cohesive workflow among them.

The private cloud part of a hybrid architecture must be compatible with the public cloud or clouds with which it's being integrated. The hypervisor and cloud software layers has to be compatible with the chosen public cloud to ensure interoperability with its APIs and services.

Hybrid clouds are frequently used for specific tasks, such as running workloads in-house that have spikes in computing demand and might need to burst into the public cloud during periods of high demand.

Multi-cloud computing is more of an overarching strategy for managing and paying for cloud services in the way that works best for an organization. The two approaches aren't mutually exclusive. Hybrid clouds are multi-clouds by definition, and a multi-cloud can be a hybrid cloud, but it doesn't have to be one. It's not required to have a private cloud component, and its various cloud components don't have to be integrated.

Differences in risks

Multi-cloud environments have developed over time at many companies that started with one cloud provider and expanded to others as IT became more comfortable with the cloud concept. This has left many organizations with a loose amalgamation of third-party cloud environments, each with a different approach to security and management.

Security is particularly daunting, given the limited visibility customers often have into how data is transferred, stored and managed in a public cloud. With less integration among the various cloud components, it can be difficult to identify security issues and coordinate threat intelligence in a multi-cloud environment.

Multi-clouds and hybrid clouds that contain multiple public clouds can mitigate the risk of a major outage at any one cloud provider. Having resources spread across multiple service providers ensures a level of data and business continuity. It also provides for backup should one provider experience an outage.

However, multiple cloud services -- whether in a multi-cloud or hybrid cloud approach -- expand the number of attack targets for cybercriminals. In addition, cloud workloads are continuously shifting, further complicating security and management.

For organizations with high compliance requirements and extensive investment in their existing data centers, such as financial institutions, a hybrid approach can have advantages. The private cloud component enables more hands-on governance and can make use of existing technology investments.

From a performance point of view, a hybrid cloud, with its on-premises component, can be the better bet. Multi-cloud environments tend to have the advantage when it comes to scalability, but often don't perform as well as hybrid clouds. Many organizations look to multi-cloud for smaller or secondary storage needs.

Cost distinctions between multi-cloud and hybrid cloud environments

When looking at multi-cloud vs. hybrid cloud environments from a cost point of view, hybrid clouds are likely to be more expensive because of the extra infrastructure and bandwidth requirements of the private cloud component. There's also the added expense of integrating on-premises data centers with the cloud infrastructure.

A multi-cloud environment using public cloud platforms can be more cost-effective, though. There are fewer or no upfront costs with the public cloud, and providers typically charge only for services used. However, a multi-cloud made up of a mix of public and private clouds will have cost constraints similar to a hybrid cloud.

The challenges ahead

Complexity is the key challenge with a multi-cloud strategy. Managing the service levels of various cloud platforms, monitoring connectivity issues across them and dealing with their associated management tools is no small task.

Hybrid clouds can be simpler to manage, because the various components are managed as one entity. However, hybrid clouds have the added challenge of constructing, running and maintaining a private cloud. In addition, enterprises must ensure private cloud workloads can interact with the public cloud components; API compatibility and network connectivity are mandatory.

With either model, there is extra complexity from connectivity, service-level agreements, threat disruptions and the need to design workloads for specific cloud environments. Different management and security systems among public cloud providers add to the challenge.

When multiple public cloud providers are used in either model, you must analyze and compare the features, prices and support of various offerings. Having the expertise needed for all aspects of both approaches in and of itself is a challenge.