AWS Cloud Migration Services

AWS cloud migration has gotten complicated with all the tools, strategies, and migration patterns flying around. As someone who has led multiple enterprise migrations from on-premises data centers to AWS, I learned everything there is to know about making this transition successfully. Today, I will share it all with you.

Migration is one of those things that looks simple on a whiteboard and gets incredibly complex in practice. You’ve got legacy applications that nobody fully understands, databases with years of accumulated data, networking configurations that evolved organically, and stakeholders with wildly different priorities. AWS provides a solid toolkit for handling all of this, but you need to know which tools to reach for and when.

Why Migrate to AWS?

Probably should have led with this section, honestly. Before diving into the how, let’s talk about the why. The most common reasons I’ve seen companies migrate to AWS include cost reduction (though this one is more nuanced than vendors admit), scalability, improved security posture, disaster recovery, and the ability to innovate faster with managed services.

The honest truth about cost savings: migration itself isn’t cheap, and your monthly cloud bill might actually be higher than your data center costs initially. The savings come from optimization over time — right-sizing instances, using reserved capacity, leveraging serverless where appropriate, and shutting down resources you don’t need. I’ve seen migrations that delivered 30-40% cost reductions within 18 months, but I’ve also seen ones that cost more than expected because teams didn’t optimize after the lift-and-shift.

The Migration Strategies (The 7 Rs)

AWS describes seven migration strategies, commonly called the 7 Rs. Understanding which strategy fits each application is the most critical decision you’ll make during a migration:

• Rehost (Lift and Shift): Move applications to AWS with minimal changes. Fast and low risk, but you don’t get cloud-native benefits. I use this for applications that need to move quickly and can be optimized later.
• Replatform (Lift, Tinker, and Shift): Make a few cloud optimizations during migration without changing core architecture. Example: moving a database from self-managed MySQL to RDS. This is my preferred default strategy — you get meaningful benefits without excessive risk.
• Refactor/Re-architect: Redesign the application to be cloud-native. Most expensive and time-consuming but delivers the biggest long-term benefits. I reserve this for applications where the business case is strong enough to justify the investment.
• Repurchase: Replace with a SaaS solution. If your on-premises CRM can be replaced by Salesforce, sometimes that’s the right move. Not really a migration, more of a replacement.
• Retire: Turn it off. During migration assessments, I typically find 10-20% of applications that nobody actually uses anymore. Don’t waste time migrating dead applications.
• Retain: Keep it on-premises for now. Some applications have regulatory, latency, or technical requirements that make cloud migration impractical today.
• Relocate: Move VMware workloads to VMware Cloud on AWS. Useful for organizations heavily invested in VMware.

Key AWS Migration Services

That’s what makes AWS migration services endearing to us cloud engineers — they’ve built a tool for every phase of the migration journey. Here are the services I use most:

1. AWS Migration Hub

Migration Hub is your central dashboard for tracking migration progress across multiple applications and services. It integrates with other migration tools and gives you a single pane of glass to see where everything stands. I set this up first on every migration project. Without it, you’re tracking progress in spreadsheets, and that gets messy fast with large migrations.

2. AWS Application Discovery Service

Before you migrate anything, you need to understand what you have. Application Discovery Service collects data about your on-premises servers — CPU utilization, memory, storage, network connections, running processes, and dependencies between servers. This data feeds directly into Migration Hub and helps you plan migration groups.

I’ve used both the agentless collector (deploys as a virtual appliance in your VMware environment) and the agent-based approach (installs on individual servers). The agent provides richer data, especially around network dependencies, which is crucial for understanding which servers need to migrate together.

3. AWS Server Migration Service (SMS)

SMS automates the migration of on-premises virtual machines to AWS. It takes incremental snapshots of your servers, converts them to AMIs, and launches them in AWS. The incremental approach means you can keep your on-premises servers running during migration and do a final cutover with minimal downtime.

4. AWS Database Migration Service (DMS)

DMS is one of my favorite AWS services, period. It handles database migrations with ongoing replication, meaning you can migrate your database while keeping it operational. It supports homogeneous migrations (Oracle to Oracle) and heterogeneous migrations (Oracle to PostgreSQL). The Schema Conversion Tool handles the schema translation for heterogeneous migrations.

I’ve used DMS for dozens of database migrations, and it’s remarkably reliable. The continuous replication feature means you can run the source and target databases in parallel, validate data consistency, and then do a clean cutover when you’re confident everything is in sync. That approach has saved me from many sleepless cutover weekends.

5. AWS Transfer Family

For transferring large datasets, Transfer Family provides managed SFTP, FTPS, and FTP endpoints backed by S3 or EFS. It’s particularly useful when you have partners or legacy systems that send data via file transfer protocols.

Migration Phases

Every successful migration I’ve led follows roughly the same phases:

1. Assessment: Discovery, dependency mapping, TCO analysis. This phase typically takes 4-8 weeks depending on environment size.
2. Planning: Define migration groups, select strategies, create runbooks, set up landing zone. Another 4-6 weeks.
3. Migration: Execute migrations in waves, starting with low-risk applications. Duration varies enormously based on scope.
4. Optimization: Right-size resources, implement reserved instances, leverage managed services. This is ongoing and where the real cost savings materialize.

Best Practices

Here’s what I’ve learned from leading migrations of varying sizes:

• Start with a non-critical application to build team confidence and work out process kinks
• Invest heavily in the assessment phase — skimping here causes problems later
• Migrate in waves, not all at once. Group applications by dependency, risk level, and business criticality
• Automate testing. Manual testing of every migrated application doesn’t scale
• Plan your rollback strategy before you start. Know exactly how to revert if something goes wrong
• Don’t underestimate the organizational change management required. People resist change
• Budget for post-migration optimization. The lift-and-shift is not the end — it’s the beginning

Conclusion

Cloud migration to AWS is a journey that requires planning, the right tools, and realistic expectations. The services AWS provides are mature and battle-tested, but they’re not magic — success depends on thorough assessment, careful planning, and disciplined execution. Take it in phases, learn from each wave, and optimize continuously. The cloud is absolutely worth the effort, but respect the process and you’ll get there smoothly.