The 6Rs of Cloud Migration: A Complete Guide to Choosing and Implementing the Right Strategy

Migrating to the Cloud is a major strategic decision for any organization. However, with so many options and approaches, determining the best path forward can be overwhelming. This comprehensive guide breaks down the 6Rs framework for Cloud migration – the six key considerations of rehosting, re-platforming, repurchasing, refactoring/re-architecting, retiring, and retaining on-premise. 

The 6Rs of cloud migration provide a methodology for assessing workloads, choosing optimal platforms, aligning with business objectives, and mitigating risk. This approach sets up IT teams for success by ensuring all factors are weighed before embarking on a cloud journey.

In this guide, you'll learn:

• The business drivers pushing enterprise cloud adoption
• How to build a strong cloud migration business case
• The 6Rs of cloud migration and how each guide's strategy
• Choosing the right cloud deployment model for your needs
• Best practices for implementing a successful migration

So, let's start leveraging the 6Rs to choose and strategically implement cloud migration.

The Growth of Cloud Computing

Before diving into the 6Rs, it's important to understand what's driving global enterprise adoption of cloud computing. The Cloud market is projected to grow to $917B by 2025 as more companies move from private data centers to cloud-based infrastructure.

What's behind this growth? A few key factors:

Flexibility & Scalability

The Cloud is a flexible infrastructure that scales up and down depending on business needs. Teams no longer need to predict capacity or buy hardware in advance. Instead, they can deploy servers and storage on demand, scaling capacity and costs to match business priorities with the addition or removal of resources.

Innovation

Cloud providers are all building next-generation infrastructure, security, machine learning, and application services. These advanced technologies allow companies to use them without building their expertise and tools. The innovation is much faster than most companies can create internally.

Cost Savings

With the cloud, many workloads can eliminate capital infrastructure costs and lower overall operating costs. It is possible to migrate to the Cloud with a pay-as-you-go model, which allows businesses to control cloud migration costs by utilizing resources according to needs. The cloud can provide significant savings over antiquated on-premise infrastructure and data centers for some applications.

Global Scale

With the hyper-scale of cloud providers, companies can go global fast. This allows the organization to deploy applications in distributed data centers located across regions and countries to bring latency-sensitive workloads near end users and satisfy data residency requirements.

Due to these business drivers, cloud computing becomes absolutely vital for digital initiatives, innovation and cost optimization. Moving key systems and applications to cloud infrastructure can provide the scalability, functionality and flexibility you need to compete in today's business landscape.

Building the Business Case for Cloud Migration

Before undertaking a cloud migration, it is critical to build a strong business case backed by sound analysis. This requires identifying business-critical goals and objectives and then determining if and how the Cloud can provide strategic value. 

By weighing the potential benefits of the Cloud against current infrastructure costs and limitations, companies can construct a business case for migration. This analysis also helps determine which applications and workloads are good candidates to move based on the key drivers the Cloud intends to address.

Once the business case is solidified, organizations can decide which migration approach or combination of approaches (the 6Rs) aligns best with their objectives. For example, a goal of faster innovation may prioritize re-architecting applications to leverage cloud-native capabilities. The business case and priorities shape the migration strategy.

Common business drivers that factor into cloud migration plans include:

1. Enabling business growth – Cloud scalability allows companies to quickly expand application capacity globally to acquire users, enter new markets, and facilitate transactions.
2. Speeding release velocity – Migrating to cloud-native architectures reduces release cycles from months to weeks or days, accelerating software innovation.
3. Reducing capital expenditures – The Cloud eliminates large upfront investments in on-prem infrastructure and data centers by leveraging pay-as-you-go and autoscaling capabilities.
4. Lowering operating expenses – The cloud's variable cost model and higher utilization and automation reduce overall spending for many workloads migrated from legacy infrastructure.
5. Business continuity and disaster recovery – The Cloud facilitates distributing applications across multiple data center regions, guarding against localized outages. Built-in data replication improves recovery objectives.
6. Compliance and data governance – Cloud providers hold dozens of compliance certifications (HIPAA, PCI, SOC, ISO), centralizing security, governance, and compliance programs.
7. Sustainability - Cloud data centers utilize green energy sources more than typical on-prem environments, supporting ESG program goals.

By identifying the key business priorities cloud migration intends to address, organizations can measure ROI and progress against original objectives. This analysis also helps construct a viable business case and compare the total cost of staying on legacy infrastructure vs. moving to the Cloud.

Now, let's examine the 6Rs framework, which provides a methodology for making cloud migration decisions based on an application's unique characteristics and business goals.

The 6Rs of Cloud Migration

The 6Rs of cloud migration create an evaluation checklist to assess workloads and choose the optimal platforms. This framework guides organizations in determining the right cloud strategy for each application to meet business objectives.

The 6Rs consist of:

• Rehost ("lift and shift")
• Replatform ("lift, tinker and shift")
• Repurchase
• Refactor / Re-architect
• Retain
• Retire

Let's explore each R further:

Rehost ("Lift and Shift")

Rehosting or "lift and shift" migration is the simplest approach to moving an application to the Cloud. Organizations can quickly reap the benefits of cloud infrastructure without major app changes. However, to maximize ROI long-term, companies should view rehosting as an interim step before re-platforming or refactoring the application.

When rehosting, IT teams utilize tools to encapsulate the entire application stack into virtual machine images (VM images). These VM images replicate the on-premises production environment containing the OS, middleware, application code and data. Cloud migration tools automate the transfer of VM images to cloud data centers and the configuration of the supporting infrastructure.

Rehosted apps operate unchanged on infrastructure as a service (IaaS) providers like AWS, Google Cloud, and Azure. Organizations pay only for the underlying computing, storage and network resources consumed. Cloud infrastructure handles hardware provisioning, maintenance, and capacity scaling.

Companies realize faster time-to-value by migrating apps in weeks rather than months. Rehosting also suits smaller IT teams with limited skills in cloud-native development. The approach minimizes disruption compared to major rewrite efforts.

However, rehosted apps miss out on the benefits offered by higher-level cloud services. They still require traditional IT management, monitoring, security patching, and business continuity protections. Without rearchitecting, companies sacrifice optimizing performance, cost, resilience, and agility in Cloudthe.

Replatform ("Lift, Tinker and Shift")

Replatforming enhances a rehosted application to increase its cloud capability. IT teams tweak the OS, middleware, and supporting services to improve elasticity, availability and operational efficiency.

Common re-platforming tasks include migrating the database to a cloud-based platform-as-a-service (PaaS) like Azure SQL or Amazon RDS. Teams also connect applications to managed cloud services for caching, messaging, notifications, and workflow.

Replatforming allows more granular scaling and auto-provisioning, which is impossible with rehosting alone. For example, moving a database to Azure SQL enables paying only for storage and compute utilized versus overprovisioning an on-prem SQL server.

Containerization brings major portability and efficiency advantages over rehosting apps directly on VMs. Migrating software into Docker containers simplifies deployment, scaling, and version management. Kubernetes orchestrates container lifecycles and workload distribution across cloud infrastructure.

Overall, re-platforming strikes the right balance between materially improving cloud benefits and avoiding the risk of a full rewrite. It positions larger digital transformation down the road.

Repurchase

In the platform/repurchase decision, organizations weigh business process disruption vs. technical disruption. Shifting to a commercial SaaS product brings process changes from adopting vendor best practices, but the approach minimizes technology risks related to legacy customizations.

Procuring a SaaS replacement eliminates the costs of operating on-premises infrastructure and apps. However, subscription licensing is based on usage or users' introduction of new variable expenses. Companies must also integrate SaaS apps with existing systems and migrate data to new data models.

Organizations should evaluate SaaS when the on-premises application provides commoditized functionality with limited competitive differentiation. Other factors include the maturation of SaaS alternatives, user readiness to adopt modern interfaces, and the availability of integration tools.

Refactor / Re-architect

Refactoring for the Cloud involves rewriting application stack components to improve scale, performance and resilience. Companies can future-proof apps by utilizing cloud-native innovations in containers, serverless computing and microservices.

For example, monolithic apps can break into discrete microservices by business capability. Microservices scale independently and upgrade seamlessly via continuous delivery practices. Containers package services consistently for deployment across on-prem and multi-cloud.

Serverless architectures outsource infrastructure management to cloud vendors. Code executes only when triggered by events like incoming API calls, file uploads or scheduled jobs. Companies pay for runtime resources used per execution.

While refactoring unlocks innovations from cloud platform engineering, companies must carefully validate benefits against the implementation risks. Refactoring success depends on architecture vision, technical execution and organizational change management across business, dev and ops teams.

Retain

Keep applications on-premises when regulatory compliance, data gravity or integration complexity outweigh the benefits of migration. Legacy platforms like mainframes and niche databases suited for specialized workloads remain on existing infrastructure.

Data gravity refers to the high costs of moving huge datasets to the Cloud. The bandwidth and latency needs make it impractical even as cloud storage costs decline. Companies analyze the tipping point where cloud migration and management expenses offset on-prem infrastructure.

Other retain cases include applications with too much technical debt and customization. The code can't practically port and run reliably on cloud platforms. A legacy batch processing system tightly coupled to specialized hardware represents one example.

Instead of migration, companies can still gain cloud oversight, automation and disaster recovery by managing on-premises infrastructure using Azure or AWS hybrid cloud services. Examples include cloud backup, site recovery, Kubernetes management, and unified monitoring.

Retire

Actively retire applications that no longer deliver differentiated business value. Typical candidates have highly manual processes better suited for commercial off-the-shelf software. Retirement also allows capital and talent to be reallocated from supporting unused legacy systems to innovation.

Companies quantify the total cost of ownership beyond the licensing, infrastructure and ops expenses. Retiring legacy apps also reduces the opportunity costs of technical debt, which limits developer productivity. Removing unused software increases security by shrinking the attack surface area.

On legacy modernization programs, retirement helps fund transformation initiatives through cost savings. The initial cost avoidance funds re-platforming viable applications and refactoring business-critical systems over time.

By methodically assessing each application against the 6Rs, organizations can map out an effective cloud migration strategy aligned with business priorities. The framework guides workload placement decisions and investment based on application characteristics and opportunities to extract business value.

This analysis may lead to rehosting simpler apps first while re-platforming business-critical systems and refactoring complex apps over longer timelines. Companies can also identify top candidates for retirement or repurchase rather than migration.

Carefully developing a 6R strategy that considers costs, benefits, and risks preempts many issues down the road and unlocks greater returns from cloud investments.

Choosing the Right Cloud Deployment Model

The 6Rs provide application rationalization for cloud migrations. Next, organizations must choose the appropriate cloud deployment model that aligns with workload placement decisions and business requirements.

The four standard cloud deployment models include:

• Public Cloud
• Private Cloud
• Hybrid Cloud
• Multi-Cloud

Let's examine the capabilities, use cases, and considerations around each model:

Public Cloud

The public Cloud offers immense flexibility and scale, making it suitable for various use cases. Global web applications can leverage the vast capacity and worldwide footprint of hyperscale data centers. Development, test, and staging environments benefit from the ability to quickly stand up resources as needed without procurement delays. Analytics platforms for big data initiatives provide nearly unlimited storage and computing for massively parallel processing. Media processing and scale streaming is possible thanks to high bandwidth networks and CDN integration. Even cutting-edge workloads like containers, serverless functions, and AI derive great advantages from public cloud services that are purpose-built for these technologies.

However, the public Cloud does come with considerations. There is no ownership or physical control over hardware, meaning security and compliance must be handled through policies and configurations. Vendor lock-in can occur when leveraging proprietary services, limiting portability between cloud providers. And low latency connectivity is required for the best performance to public endpoints.

Private Cloud

The private Cloud allows organizations to reap many rapid provisioning and scalability benefits of public infrastructure, but it is contained fully behind the corporate firewall. This makes it well-suited for workloads involving highly sensitive data with strict regulatory controls that preclude the public Cloud. Latency-sensitive applications such as voice and video that require local access also align with private cloud placement where bandwidth is abundant. Legacy applications that cannot be re-architected for the Cloud make good candidates for lift-and-shift migrations to private virtualized infrastructure. The private Cloud provides an avenue for integrating edge capacity with public cloud resources.

However, the private Cloud does not come without its challenges. IT staff will need training in virtualization, automation, and cloud-native operations models to build and manage private infrastructure effectively. Budgeted capacity limits in on-premises data centers can constrict scaling workloads. Tools for cloud interoperability and hybrid connectivity must be evaluated and implemented for private cloud success.

Hybrid Cloud

A hybrid cloud delivers the best private and public infrastructure by seamlessly bridging internal and external capacity. This provides nearly unlimited options for extending data centers with cloud resources. When internal capacity is insufficient, organizations can burst batch processing jobs or traffic spikes transparently into the public Cloud. Critical data can be backed up or mirrored to cloud storage for disaster recovery purposes. Global applications can deploy regionally to the local private Cloud while leveraging a central public cloud backend. And legacy systems can be maintained on existing infrastructure while next-gen workloads innovate on public cloud platforms.

However, the flexibility of the hybrid model does introduce additional complexity. Careful network planning is required to ensure secure and performant connectivity between domains. Consistent identity and access policies must be implemented across environments. Compliance and regulatory considerations get more complicated, spanning mixed infrastructure. Seamless interoperability between private and public clouds relies heavily on specialized tooling and well-defined processes for cross-cloud management.

Multi-Cloud

Rather than committing to a single public cloud provider, many organizations choose to diversify across AWS, Azure, and GCP in a multi-cloud approach. This allows workloads to be strategically placed on optimal platforms based on capability, performance, or cost considerations. It also helps mitigate the risk of vendor lock-in by maintaining portability across cloud environments.

Multi-cloud enables several use cases that are not easily accomplished within a single cloud. Portable containerized applications can be distributed across cloud properties for redundancy or regional placement purposes. Disaster recovery configurations can replicate data and systems across multiple vendors. Cloud management tools aggregate monitoring and visibility data across disparate public cloud accounts. Leveraging differing discount models and spot pricing can be used to optimize cloud spending across providers.

The multi-cloud strategy does require additional oversight and tooling complexity compared to a single-provider approach. However, the flexibility, risk mitigation, and cost optimization benefits often outweigh the modest incremental overhead. As cloud strategies mature, most organizations adopt a multi-cloud model to match the right cloud services to application needs while avoiding vendor lock-in.

Implementing a Successful Cloud Migration

Developing a solid cloud strategy and business case provides direction, but executing a seamless migration requires meticulous planning and governance. How can organizations set their teams up for success? Here are the best practices to smooth the transition to the Cloud:

1. Take Inventory

The first step involves creating a complete inventory of infrastructure, applications, dependencies, data flows, and interfaces. Thoroughly documenting the existing landscape prevents surprises down the road as hidden touch points surface.

Teams should capture integration points, data models, security policies, backup processes, disaster recovery tests, and performance benchmarks as key baselines before migration.

2. Assess and Map Dependencies

With a complete inventory, analyze upstream and downstream application dependencies, data flows, network links, and user and system access requirements.

Identify which application groups should move together in later migration waves based on tight couplings. Also, Windows availability and testing procedures for integrated systems must be determined.

Documenting these technical and business dependencies through visual maps and diagrams ensures successful migrations without unplanned downtime or access issues.

3. Develop the Migration Plan

Next, findings will be consolidated into a master cloud migration plan that sequences tasks into manageable phases. Applications will be assigned into migration waves based on the 6R application rationalization, sizing for network and storage needs, calculating related costs, and defining owner teams.

The plan should specify timelines, resource requirements, testing procedures, and rollback steps. It should also build in ample buffers and contingency time for unforeseen issues.

Focus initial waves on simpler applications to validate processes before tackling complex mission-critical systems. Target quick wins that build business confidence in cloud capabilities.

4. Set Up Governance Early

Establishing cloud governance, security, compliance, and cost management controls early on will help establish guardrails as usage scales across projects.

Establish access controls, VPNs, encryption standards, data protection and backup requirements for each workload according to its sensitivity level.

Enforce these policies automatically, provide a view into resource consumption and prevent configuration drift.

5. Prioritize Culture Change

Technology migrations always affect people and processes. Education, skills training, and clear communication help teams embrace modern operations practices that fully realize cloud value.

Instead of resisting change, promote a culture that welcomes innovation and change. Make cloud proficiency a key competency and provide learning opportunities for staff at all levels to become comfortable operating in the Cloud.

Conclusion

Enterprise workload migration to the Cloud enables organizations to innovate faster, reduce costs and achieve global scale. The 6Rs provide a proven framework for deciding which applications should migrate to the Cloud and how best to do it.

By carefully evaluating each application against business goals and technical requirements, IT teams are set up for success. Choosing the right deployment model and practicing cloud governance best practices further ease the transition and maximize the cloud's potential.

Cloud-based digital transformation is the key to moving to the Cloud, but you need to plan carefully and align technology with people and processes. A good map and compass are essential to any journey into uncharted territory, and the 6Rs are that for cloud migration.

‍