On-premise to Cloud Migration: A Practical Guide 

Moving your infrastructure from on-premise to the cloud feels like a massive undertaking. And it can be. But with the right approach, what seems like an overwhelming project becomes a series of manageable steps that transform how your business operates.

Whether you’re looking at Azure, AWS, or another cloud platform, the fundamentals remain the same. You need a solid strategy, the right tools, and a clear understanding of what you’re trying to achieve. In this guide, we’ll walk through everything you need to know about migrating from on-premise infrastructure to the cloud.

If you’re specifically interested in Azure migration, you might also want to check out our guide on smart cloud migration strategies which dives deeper into Azure-specific approaches.

Moving your tech to the cloud is a fundamental business transformation. Some of our favourite reasons to do it are: 

Cost predictability is often the first driver. Instead of massive upfront investments in hardware that might sit idle, you pay for what you use. No more buying servers sized for peak capacity that only happens twice a year. The shift from CapEx to OpEx also makes budgeting more straightforward and frees up capital for other investments. 

Scalability changes everything about how you plan for growth. Need more resources for a project? Spin them up in minutes. If a project is finished, scale back down. You can’t really do that with physical servers. 

Remote working is non-negotiable for many businesses. Cloud infrastructure means your team can access resources from anywhere, without complex VPN setups or security compromises. It lets everyone work from anywhere securely. 

Innovation happens faster in the cloud. Want to try out machine learning? Spin up a GPU cluster for the afternoon. Need to test a new app architecture? Build it, test it, tear it down. All of this happens without procurement cycles or installation delays. 

Security and compliance is also a big one. It might sound counterintuitive, but cloud providers often provide better security than most orgs can achieve on-prem. They have entire teams dedicated to security, compliance certifications, and keeping infrastructure patched and protected. Yes, you’re still responsible for securing your applications and data, but the heavy lifting of infrastructure security is handled by experts. 

While Azure and AWS dominate the cloud market, you’ve got options. Google Cloud Platform brings strong data analytics and machine learning capabilities. Oracle Cloud might make sense if you’re running Oracle workloads. IBM Cloud has its place in certain enterprise scenarios. But for most organisations, the choice comes down to Azure or AWS, and increasingly, using both. 

Azure makes particular sense if you’re already invested in Microsoft technologies. The integration with Microsoft 365, Active Directory, and other Microsoft services is hard to beat. Plus, if you’re running Windows Server or SQL Server, Azure often provides the smoothest migration path. Our Azure migration tools toolkit covers the specific tools that make Azure migrations easier. 

AWS brings massive scale and the broadest range of services. If you need specific, cutting-edge services or want the most extensive third-party marketplace, AWS delivers. Their migration tools are mature and well-documented, though the learning curve can be steeper if you’re not already familiar with their ecosystem. 

Multi-cloud strategies are becoming more common, and for good reason. Maybe you want Azure for your Microsoft workloads and AWS for your web applications. Or perhaps you need to avoid vendor lock-in for regulatory reasons. Just remember that multi-cloud adds complexity. You’ll need expertise in multiple platforms and tools to manage across them. 

Hybrid approaches aren’t going away either. Some workloads might need to stay on-premise for regulatory, performance, or technical reasons. Both Azure Local and AWS Outposts let you run cloud services in your own data centre, giving you a bridge between on-premise and cloud. (Check out our deep dive into Azure Local to find out how it brings Azure services to your own infrastructure.) 

The “5 Rs” framework helps you decide how to handle each application in your portfolio. It’s a way of categorising your migration approach that’s become industry standard. 

• Rehost (lift and shift) is the quickest path to the cloud. You take your applications as they are and move them to cloud infrastructure. No changes to the application, just a new home. It’s fast and relatively low-risk, but you won’t get all the cloud benefits. Still, it’s often the right choice for getting out of a data centre quickly or moving stable applications that don’t need modernisation. 
• Replatform means making small tweaks to take advantage of cloud services without major surgery. Maybe you move your database to Azure SQL or AWS RDS, or shift from self-managed web servers to managed services. You get some cloud benefits like reduced maintenance and better scaling, without completely rearchitecting your application. 
• Refactor involves completely rearchitecting your application for the cloud. This is where you break monoliths into microservices, embrace containers, or rebuild with serverless architectures. It can take some major time and effort, but you get maximum cloud benefits like infinite scaling, reduced costs, and improved resilience. 
• Repurchase is about swapping your old application for a SaaS solution. Why migrate your on-premise CRM when you could move to Salesforce or Dynamics 365? Why maintain your own email servers when Microsoft 365 or Google Workspace exist? Sometimes it’s smarter to subscribe to a service than maintain your own. 
• Retire is the one everyone forgets. Sometimes the smartest move is to switch something off entirely. That reporting system nobody’s touched in two years, and the backup application for a system you decommissioned last year? Maybe it’s time to let them go. You’d be surprised how many applications are running just because nobody’s brave enough to turn them off. 

To decide which one of those R’s will be best for you, you’ll first want to take stock of your current situation. 

This discovery phase often takes a while, but it’s time well spent. 

Start with a complete infrastructure inventory. Not just servers and storage, but network configurations, firewall rules, load balancers, and all those forgotten systems that somehow keep running. Document dependencies between systems. That ancient server in the corner might be running a critical authentication service that three other apps depend on. 

Application assessment goes beyond just listing your apps. Which ones are business-critical? What are their performance requirements? Some applications might have hard-coded IP addresses or local file dependencies that need addressing before migration. Others might have licensing restrictions that affect where they can run. 

Don’t forget about data classification. Where does sensitive data live? What are your compliance requirements? GDPR, financial regulations, or industry-specific requirements might dictate where data can reside and how it needs to be protected. 

Skills gap analysis can be a pain, but it is necessary. Moving to the cloud needs different skills than managing on-prem infrastructure. Your VMware expert might need training on Azure Virtual Network. Or your database admin needs to understand managed database services. Plan for this training early. 

Total cost of ownership calculations help build the business case. Remember to factor in not just the cloud costs, but reduced hardware maintenance, power and cooling savings, and the opportunity cost of your team’s time. Also think about migration costs themselves: tools, training, potential downtime, and possibly consultant fees. 

Migration isn’t a single event. It’s a journey with distinct phases, each building on the last. Generally, it’ll pan out in phases that look like this: 

1. Discovery and planning is where you figure out what you’re dealing with. You can use automated discovery tools to map your environment, like Azure Migrate, AWS Application Discovery Service, or third-party options like Cloudamize. Classify applications by complexity and criticality. Build your migration roadmap, starting with simple, low-risk apps to build confidence and expertise. This phase often reveals surprises, like software everyone forgot existed or dependencies nobody documented. 
2. Proof of concept tests your approach with a non-critical application. Pick something representative but not mission-critical: maybe a development environment or internal tool. This lets you test your migration process, validate your tools, and identify issues before they affect important systems. You’ll learn more from this first migration than from weeks of planning. 
3. Full migration execution is where the real work happens. By now, you should have refined your process, trained your team, and built confidence with initial successes. Migrate in waves, grouping applications by dependencies and business requirements. Always have a rollback plan and test thoroughly at each stage. And remember to communicate constantly with stakeholders. 
4. Optimisation and governance starts once applications are running in the cloud. Right-size resources based on actual usage, and bring in cost controls & monitoring. Set up governance policies for security, compliance, and cost management. This isn’t the end of migration; it’s the beginning of your cloud operations. 
5. Continuous improvement acknowledges that cloud migration is never really “done.” New services appear constantly. Security needs continuous attention. So you really want to build a culture of continuous improvement, rather than treating migration as a one-time project. 

The right tools make migration much easier. Both Azure and AWS have some really useful toolsets to choose from, and there are third-party options to fill in the gaps. 

Assessment tools help you understand what you’re migrating. Azure Migrate gives you discovery, assessment, and migration capabilities in one package. AWS Migration Hub does similar things with its Migration Evaluator. These tools scan your environment, map dependencies, estimate costs, and even predict performance in the cloud. 

Data migration tools vary based on your needs. For big datasets, physical transfer services like Azure Data Box or AWS Snowball might be fastest. For ongoing replication, tools like Azure Database Migration Service or AWS Database Migration Service handle the heavy lifting. Don’t forget about basics like robocopy or rsync for simple file transfers. 

Application migration gets complex quickly. Azure Migrate handles Windows and Linux servers, while AWS Application Migration Service (formerly CloudEndure) handles block-level replication. For containerised applications, tools like Azure Migrate for Containers or AWS App2Container help modernise as you migrate. 

For more details on Azure-specific tools, head over to our Azure migration tools toolkit. 

Years of cloud migrations have taught the industry some hard lessons. Learn from others’ mistakes by following these best practices for on-premise to cloud migrations: 

• Start with non-critical workloads. Your first migration shouldn’t be your ERP system. Pick development environments, test systems, or internal tools. Build expertise and confidence with systems where mistakes won’t stop the business. 
• Implement governance early. It’s easier to start with good practices than fix bad ones later. Set up naming conventions (our Azure naming conventions guide can help), tagging standards, and cost allocation from day one. 
• Monitor costs from the beginning. Cloud costs can spiral without proper controls. Set up budgets, alerts, and regular reviews. Tag resources properly so you know what’s costing money and why. 
• Keep data secure during migration. This is non-negotiable. Always use encrypted connections, VPNs, or physical device encryption when transferring data. Understand who has access to data during migration and how it’s protected. For large datasets (anything over a few terabytes), physical transfer services might be both faster and more secure than network transfers. Check data integrity at every stage using checksums and validation tests. Don’t assume everything transferred correctly. 
• Document everything. Not just technical documentation, but the reasoning behind decisions and lessons you learned. Build runbooks for common tasks: future you will thank current you. 
• Train your team throughout the process. Don’t wait until after migration to start training. Involve your team in planning and execution. They’ll learn by doing and feel ownership of the new environment. 
• Plan for rollback. Hopefully you won’t need it, but plan as if you will. Know exactly how to reverse each migration step. Test your rollback procedures, and define clear criteria for when to pull the trigger. 

Every migration faces obstacles. Knowing which ones you might face will help you prepare: 

• Legacy application dependencies cause lots of delays compared to other technical issues. That old application might depend on specific Windows versions, hardcoded server names, or ancient protocols. Sometimes refactoring is necessary. Sometimes you need creative workarounds. Sometimes you just need to plan for keeping some systems on-premise. 
• Bandwidth limitations affect the timelines of your migration. Calculate how long data transfers will take and plan accordingly. Consider temporary bandwidth upgrades or physical transfer services for large datasets. 
• Compliance and regulatory hurdles vary by industry but can’t be ignored. Data residency requirements might limit your cloud region choices. Audit requirements might need specific logging configurations. Get your compliance team involved early to avoid the faff. 
• Organisational resistance is real and needs addressing. People don’t usually like change, especially when it affects their daily work. Communicate the benefits clearly. Involve skeptics in planning and celebrate early wins in a way that’s visible to everyone. 
• Cost overruns happen when migrations take longer than expected or cloud resources aren’t properly managed. Build contingency into your budget and monitor costs weekly during migration. Be prepared to adjust your approach if costs spiral. 

Every on-premise to cloud migration needs a proper checklist to keep things on track. Whether you’re migrating a handful of applications or your entire data centre, having a structured list of tasks helps make sure nothing gets missed. 

Feel free to adapt this to your specific situation, but these are the essentials that every migration should cover. 

Migrating from on-premise to cloud is a significant undertaking that touches every part of your IT infrastructure (and your company). Getting a great result comes from careful planning, the right tools, and a methodical approach. Whether you choose Azure, AWS, or another platform, the principles remain the same: understand what you have, plan your approach, execute carefully, and optimise continuously. 

And getting to the cloud is just the beginning. Once you’re there, you can start thinking about ongoing optimisation: right-sizing resources, managing costs, and taking advantage of new cloud services as they become available. 

While it’s possible to handle migration internally, you don’t have to do it alone. Working with an experienced partner can make the journey much smoother. At Synextra, we’re regulars in the cloud migration game. We’ve seen the pitfalls and know how to keep your business running smoothly during the transformation. 

Ready to start your cloud journey? Contact us today.