Some of the biggest reasons to migrate to the cloud are to reduce costs and optimize infrastructure. Migrating to the cloud can help organizations move spending from a capital expenditure model to an operational expenditure model, reducing the need to own, operate, maintain, and refresh expensive equipment in on-premises data centers. 

Migrating to the cloud can help companies improve performance and increase uptime. The cloud also helps companies modernize workloads, avoiding burdensome licensing fees from legacy applications. The cloud can help organizations safeguard their data while increasing governance and compliance with regulators across the globe.

Organizations also migrate to the cloud to:

Unlock data analytics

Migrating existing apps to the cloud can help businesses create more value out of tools they already use, such as CRM, SAP, marketing databases, and more. Getting these systems modernized in the cloud helps companies unlock their data and find new business opportunities while increasing organizational agility to address problems. 

Increase agility

The cloud provides organizations with on-demand IT resources, so they don’t have to wait weeks or months to build apps or install on-premises hardware. The cloud enables organizations to adapt to market changes and competitor actions much more quickly, increasing flexibility for go-to-market strategies.

Consolidate and modernize data

By moving away from on-premises data centers, companies have the opportunity to consolidate their data and organize it in a universal data platform, opening up opportunities for more robust and sophisticated digital transformations.

Organizations can choose from different types of cloud migrations, depending on their goals and objectives. 

A full data center exit migration is the process of moving all applications, services, and datasets from one or more data centers to a public cloud. Depending on the size of the organization, a full data center exit can be a long process requiring more than a year of planning, testing, and execution. 

An organization may want to move from one cloud vendor to another for a variety of reasons, including changes in service level agreements, better security practices, or for access to more advanced artificial intelligence and machine learning tools. Major vendors will typically have toolsets, services and lists of third-party vendors that can help an organization move from one public cloud provider to another.

Instead of a full data center exit, organizations may wish to migrate some of their software, services, or datasets from on-premises servers to the cloud where they can be more efficient and easily managed. Business intelligence, data analytics, customer resource management (CRM), machine learning and artificial intelligence apps, and datasets are typical types of applications that are migrated to public clouds.

More targeted migrations can consist of just a specific type of workload, which are resources running in the cloud that consume some type of resource, such as computing power or storage capacity. Examples include development environments, document creation and management, distributed databases, 3D modeling, or video encoding.

Cloud migration is a multi-phase process that includes assessment, planning, migration, and optimization/modernization. A holistic, end-to-end migration program helps organizations lower risk, control costs, and simplify the path to cloud success.

Organizations have several options when beginning the cloud migration process. They can try to do it themselves with existing employees; they can partner with the public cloud vendor and utilize its suite of migration tools; and they can employ third-party migration partners to provide technical expertise and support.

A thorough checklist can provide a roadmap that organizations can follow to ease the migration to the cloud. A checklist can include the following items and more.

• Define the resources and capacity of applications
• Create a list of applications, who uses them and how often
• Identify key stakeholders early in the process
• Determine which applications are cloud eligible
• Specify security and compliance requirements

• Pick a strategy for each application
• Design cloud infrastructure such as compute, networking, security, storage, etc.
• Identify the capabilities of the workloads that will be migrating
• Create migration plans for apps and their data

• Devise a testing strategy before beginning migration
• Test data migration and synchronization
• Validate security controls
• Document necessary changes to be done as part of the migration
• Plan the time for application cutover

• Migrate according to the plan for each app, workload, and instance
• Migrate in stages, executing each wave, then validating in the cloud
• Apply lessons learned from one way to the next wave

• Monitor application and cloud usage
• Optimize user experience
• Monitor cloud costs and adjust as needed
• Upgrade apps and systems to more modern solutions, like PaaS or SaaS

The most common migration strategies exist on a spectrum from a straight migration with little to no changes to apps and virtual machines (rehosting), to a complete rethinking of the entire digital infrastructure (re-architecting or replatforming).

• Rehost: lift and shift
• A rehosting cloud migration strategy aims to make as few changes during the migration as possible, redeploying applications to the cloud without making substantial changes to how they are configured. 
• It is the most straightforward cloud migration strategy where administrators just “lift” their applications, workloads, virtual machines, and server operating systems and “shift” them to the new operating model in the public cloud. The same software that was running in the data center is now running in the cloud. 
• The drawback to a rehosting strategy is that it often does not take advantage of all the cloud-native capabilities and efficiencies that make public clouds so powerful and useful. 
• A rehosting migration strategy is best for organizations with predictable peak usage patterns (like the tax industry or food delivery), and is also commonly a ‘first step’ in a larger digital transformation project.
• Replatform: lift and optimize
• A replatforming cloud strategy is the next step from a rehosting strategy, lifting the existing applications, workloads, and virtual machines and then optimizing them for the new cloud environment. For instance, a service may replatform a workload to the cloud to be able to take advantage of cloud-based microservice architecture, or containers like Kubernetes. 
• The benefit of a replatforming cloud migration strategy is that the applications will have higher performance and more efficiency running in the cloud. The drawback is that replatforming takes more work to accomplish than a straight lift and shift. The new cloud platform will have a different underlying code base, which will mean several rounds of testing to make sure everything is running at its optimal level. 
• A replatforming cloud migration strategy is best for organizations that want to take advantage of all the core competencies of the cloud such as elastic computing, redundancy, improved performance, and security.
• Refactor: move and improve
• A refactoring cloud migration strategy means taking applications and re-engineering them to be cloud-native. 
• Refactoring often means changing the code of an application without altering its front-end behavior or experience. For example, a refactored application may be broken up from long strings of code into more modular pieces that can better take advantage of cloud capabilities, thus improving the performance of the code. 
• A refactoring strategy is often driven by the need to give existing applications new capabilities, such as increasing scalability, adding machine learning or artificial intelligence capabilities, or faster and more intuitive data analysis. 
• Refactoring can be more complex than rehosting, but also allows an organization to set priorities on which applications are moved based on business needs, giving companies greater flexibility and the ability to keep up with the competitive ecosystem.
• Re-architect
• A re-architecting cloud migration strategy is similar to refactoring but instead of restructuring how the application’s code works, it changes how that code functions in order to optimize the application and take advantage of cloud-native properties like scalability, security, and agility. 
• One example of re-architecting an application is to take one large, monolithic application and turn it into several independent microservices. 
• Re-architecting takes more time and effort than refactoring, increasing complexity while potentially introducing bugs or security issues into the new applications.
• Rebuild
• A rebuilding cloud migration strategy is when an organization takes an application and rewrites it entirely for the cloud. It is often easier to build an application from scratch than it is to refactor its old code to work in a cloud environment. 
• A rebuilding strategy allows an organization to plan from the ground up, choosing which cloud-native tools and capabilities to utilize from the beginning. 
• The drawback in a rebuilding strategy is that it takes time and can introduce bugs or other performance issues that developers had not encountered in the legacy version of the app.
• Repurchase
• A repurchasing cloud migration strategy is when an organization moves from a purchased on-premises application to cloud-hosted Software-as-a-Service equivalent. For instance, moving from on-premises collaboration software and local storage to Google Workspace’s cloud-hosted apps like Docs, Sheets, Slides, and Google Drive. 
• From a resources perspective, a repurchasing strategy can be a lot easier than refactoring, rebuilding, or re-architecting. 
• The drawback to a repurchasing strategy is that it can be a lot more expensive and organizations do not get the granular features of controlling their own cloud environments.

Full-scale migrations to the cloud can be complicated, multi-year operations. Going into a cloud migration, organizations need clear goals and attainable business objectives to aim towards while the migration is taking place. Organizations should have an understanding of what their cloud environment will look like at the end of the migration, such as if it will be a public, private, hybrid, or multicloud ecosystem. Does the migration require third-party vendors or significant assistance from the cloud provider? What apps will be run on a SaaS model? How will data be organized in the new environment? The answers to these and other strategy questions are the first challenge in migrating to the cloud.

Organizing IT operations in the cloud is different from running the same processes in on-premises environments. The cloud simplifies the use of operating models such as DevOps, automation, and infrastructure as code. Organizations will need to hire or retrain employees to perform necessary functions in a cloud environment. During the migration, organizations should allocate time for employees to train on cloud environments and obtain new certifications.

Security practices change when migrating between an on-premises environment and the cloud. Identity and access management becomes much more important in the cloud, which can create complexities for IT administrators. Organizations need to understand new security tools and best practices, such as instituting data loss prevention and zero-trust architectures. Even with robust security tools, it is the responsibility of the organization to tackle challenges around data governance and compliance policies when moving data from one environment to another.

Migrating to the cloud changes the operating model of an organization. With many moving parts, understanding all the new costs and expenditures can be daunting. Cost management becomes an ongoing challenge with cloud migration such as understanding new fee structures, billing cycles, resource consumption, software subscriptions, and calculating additional support and training. When migrating to the cloud, companies sometimes overprovision resources, and thus initially overspend on cloud resources. Some cloud providers offer proactive recommendations to help organizations adjust cloud costs and budgets.