Today, there is no single cloud computing model. Cloud technologies have expanded, matured and proliferated to support organizations' most demanding business purposes.
The proliferation of cloud technologies is particularly confusing to businesses new to cloud adoption, and they are sometimes baffled by the distinction between multi-cloud and hybrid cloud. Both architectures have a distinct definition and purpose. Here we will tease them apart and offer some tips on how to select the best architecture for your applications and business goals.
What is multi-cloud?
A multi-cloud technology strategy involves two or more cloud computing platforms or providers to handle various business tasks. A business might perform some tasks that use AWS, another set of tasks with Google Cloud Platform, and yet other tasks with Microsoft Azure.
A multi-cloud approach can be extensive and complex depending on the number of clouds involved and the ways that a business consumes each cloud resource or service. For example, a business might employ a public cloud provider's IaaS to host its workloads. At the same time, it could use specialized SaaS or PaaS providers for business services such as productivity tools (Office 365), employee expense tracking and reporting (Concur), and so on, where each service is its own cloud.
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Benefits of multi-cloud
So why undertake such complexity? There are some compelling reasons why a business might explore a multi-cloud approach. They are as follows:
- Reduce local infrastructure. A business outsources some or all of its on-premises infrastructure to third-party providers to shed the burdens of hardware, software, maintenance and support -- for example, move business email from an in-house Exchange server to Exchange Online.
- Leverage specific services. Clouds often specialize in ways that complement the provider's business background and strengths. For example, a business might use one cloud provider to host a test and development workload but use a different cloud provider's more mature AI and machine learning (ML) services.
- Manage costs. Local infrastructure requires a capital investment no matter how or even whether it's used. Cloud resources and services employ a "pay-as-you-go" model where costs scale based on actual use. For example, a SaaS platform may charge based on the number of users (seats), where other cloud services charge based on usage or recurring monthly fees. These costs are well-documented by providers, and businesses can see precisely where money is spent.
- Improve resilience and compliance. A business must run and remain secure in the face of disruption -- this is the central tenet of compliance. A business might deploy a redundant workload in two or more clouds to handle more application traffic and enhance resilience. If one cloud goes offline, the other cloud can continue to function and support the workload.
Challenges of multi-cloud
The complexities of a multi-cloud approach extend beyond just juggling resources, services and third-party providers. Organizations that embrace a multi-cloud environment potentially face some new risks and challenges rarely posed by on-premises infrastructure, such as the following:
- Security complexity. Multiple cloud providers and environments means grappling with multiple security configurations and authentications to ensure user security as well as the security of sensitive business data. It may be impractical to establish a common security configuration or workflow for all cloud providers. Also, there may be a high risk of security vulnerabilities in multi-cloud environments.
- Regulatory standards. Although multi-cloud strategies can enhance compliance in areas such as workload resilience, there are other threats to regulatory compliance, such as improper data storage locations or inadequately secured data in the cloud.
- Network security. With workloads and data in clouds, it's unavoidable that sensitive business data will traverse a public network such as the internet. Businesses must take careful precautions to ensure the security of all cloud-related data through encryption.
- Provider disruption. A business must consider the implications of network and provider disruption and devise contingency plans. Understand the impacts of an internet outage between the business and provider, a malicious attack on the provider, a deprecation of needed services or even the effects of a provider merger, acquisition or bankruptcy. It may be necessary to find another suitable cloud provider available or repatriate the service in-house.
Multi-cloud management tools
Any organization with a multi-cloud approach must recognize the resources and services it uses, understand their configurations and monitor their performance.
IT teams can use tools to handle multiple clouds from a single interface. These tools support a wide array of cloud platforms such as AWS and Azure as well as complementary tools such as Kubernetes to manage container-based workloads. Multi-cloud management tools also should support strong abstraction, orchestration and automation; handle security such as identity management and data encryption; control policy governance and compliance; monitor performance of the infrastructures and applications; and help manage costs.
What is hybrid cloud?
A hybrid cloud technology strategy merges a private cloud or on-premises infrastructure, or both, with a public cloud environment to create a single cloud computing environment that combines the best of both.
A business might create a private cloud to support self-service resource provisioning for software developers, or run an important cloud-native application locally. The business can also connect that private cloud to a public cloud to gain extra resources or use specialized services.
Types of hybrid clouds
The key to a hybrid cloud is uniformity -- consistent access and delivery of resources and services that smoothly integrate public and private clouds. There are two popular approaches to establish a uniform hybrid cloud infrastructure.
The traditional approach is to build a private cloud stack, using common platforms such as OpenStack that can integrate with a public cloud. These are sometimes referred to as "heterogeneous" hybrid clouds because the resulting hybrid cloud infrastructure includes technologies and platforms from a variety of providers.
Another approach is to use specialized appliances that contain the software stack and services specifically designed to integrate with the desired public cloud. Examples include Azure Stack, Google Anthos and AWS Outposts. These are sometimes called "homogeneous" hybrid clouds because the resulting infrastructure incorporates technologies from a single public cloud provider.
An enterprise must consider the costs, performance and management requirements, as well as the technology roadmap, to choose the hybrid cloud program that best fits its needs.
Benefits of hybrid cloud
Organizations may choose to add a hybrid cloud strategy for a variety of reasons, including the following:
- Cost management. Infrastructure is a sunk cost, and some workloads and data will always require local infrastructure, so a business may choose to build a private cloud with on-premises systems that's fast and flexible. Meanwhile, it can relocate other workloads and data to the public cloud as needed to take advantage of the "pay-as-you-go" or "pay-per-use" models. Merging these public and private clouds into a consistent hybrid cloud enables easy migration of workloads and data as cost benefits allow.
- Security and compliance. Some workloads and data must run on local infrastructure for security, compliance and regulatory requirements. A hybrid cloud allows the business to establish and apply consistent security and compliance processes to address regulatory concerns.
- Scalability. Workloads may need flexibility to add or drop resources as traffic ebbs and flows. Hybrid clouds allow workloads and data to shift between private and public clouds as demand dictates.
- Business agility. Competitive advantages, new business opportunities and faster time-to-market usually rely on rapid infrastructure provisioning to support activities such as new workload testing, deployment and migration. A hybrid cloud strategy is uniquely suited to such agility -- staff can provision resources on a private cloud, and then move workloads and data between public and private clouds.
Challenges of hybrid cloud
While a well-designed hybrid cloud can offer compelling benefits for a busy enterprise, there are also various hybrid cloud drawbacks to consider, including the following:
- Lack of capability. Building a hybrid cloud from scratch, especially a cobbled-together heterogeneous hybrid cloud, can be technically challenging and time-consuming. Not all hybrid cloud projects are successful or meet the organization's expectations. A business must possess solid employee skills and tools before it embarks on a hybrid cloud initiative, and proceed in carefully orchestrated phases.
- Costs. While hybrid clouds can benefit overall cost management, it's still expensive to keep and maintain additional private cloud infrastructure, as well as develop new workflows and guidelines for private and hybrid cloud use. Consider all of the costs when planning a hybrid cloud project.
- Integration problems. The whole point of a hybrid cloud is to integrate a private and public cloud, but in reality this is one of the biggest challenges. (Homogeneous hybrid cloud products make this considerably easier.) In addition, the hybrid cloud may require upkeep with changes and updates to match updates to the public cloud provider's infrastructure or software stack.
- Network disruption. Hybrid clouds depend on WAN connectivity. Any disruptions can render the hybrid cloud inoperative.
Multi-cloud vs. hybrid cloud: What are the key differences?
Hybrid cloud and multi-cloud deployment models differ in purpose and infrastructure design, and consequently they have similarities and differences. Both hybrid and multi-cloud do the following:
- provide flexibility and redundancy;
- enable the business to deploy highly tailored infrastructures; and
- support the transition of capital investments into operational expenses.
At the same time, there are important distinctions, such as the following:
- Hybrid clouds always involve public and private clouds, whereas multi-clouds involve only public clouds (IaaS, PaaS and SaaS).
- Hybrid clouds connect a private and public cloud to establish a single ubiquitous environment (including management); multi-clouds do not even attempt such interoperability.
Can a hybrid cloud be multi-cloud?
Given their similarities and differences, hybrid cloud and multi-cloud are typically regarded as separate approaches or architectures, both with their own purpose.
However, hybrid clouds and multi-clouds can coexist. A business can build a private cloud for internal use, merge that private cloud with a public cloud to create a hybrid cloud, and then add or integrate multiple other clouds (whether IaaS, PaaS or SaaS) to deliver specific resources or services to the business. Similarly, a business could create a hybrid cloud with one public cloud provider, but also consume the resources and services of other public clouds outside of the hybrid cloud environment.
It is theoretically possible to create a "hybrid multi-cloud," but this would require a private cloud that integrates with two or more public clouds simultaneously. In practice, the complex technical hurdles involved in such simultaneous integrations are rarely worth the effort. Only the largest and technically adept enterprises with demanding hybrid project requirements should consider such an endeavor.
How to choose which cloud is best for your business
The general criteria to choose a hybrid or multi-cloud strategy can be reduced to a matter of ownership or control. The choice isn't always obvious or easy, but it will always be driven by specific business needs and goals.
When to choose a hybrid cloud strategy: A business requires cloud flexibility, resources, and services, but is obligated (by choice or regulatory standards) to host certain data or workloads locally and cannot place that data or workloads outside of the organization's on-premises data centers or direct geopolitical control. For example, a business wants to build cloud-native applications and host some applications in the public cloud, but must run certain critical workloads locally.
When to choose a multi-cloud strategy: A business requires services, resources, infrastructure or cost models provided by specific cloud providers. For example, a business might opt for VM and storage instances from one public cloud provider, business applications (such as productivity or finance) from various SaaS providers and perhaps AI/ML cloud services or language cloud services from other cloud providers.
Always choose a cloud architecture based on specific business needs and goals. There is no "best" cloud. Rather, understand the complexities and challenges that each cloud option presents.