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The Complete Checklist for AWS Cloud Migration: Zero-Downtime Cloud Move Step-by-Step

  • software735
  • Dec 4
  • 4 min read

Updated: Dec 10

AWS cloud migration

Migrating to AWS can feel like moving an entire house—while still living in it. Things have to keep running, customers shouldn’t notice disruptions, and your team must stay sane throughout the process. The good news? With the right AWS cloud migration checklist, you can smoothly plan, migrate, test, and optimize your move with zero downtime.

Whether you’re going for a lift and shift migration, a modernized refactor, or a hybrid model, the real goal stays the same: move to AWS safely, efficiently, and without breaking anything.

This guide walks you through a complete step-by-step checklist to migrate to AWS confidently—without unexpected surprises, cost spikes, or post-migration chaos.


1. Pre-Migration Assessment: Know What You’re Moving

Before anything else, you need clarity. This phase sets the foundation for your entire cloud move.

✔ Inventory all applications and dependencies

Map out your servers, databases, APIs, security groups, cron jobs, DNS records—everything. Missing even a small dependency can break the migration later.

✔ Identify what can be lifted-and-shifted vs modernized

Not every workload deserves a full refactor.

  • Legacy apps → lift and shift

  • High-traffic apps → possibly containerize

  • Microservices → move to EKS/ECS This mixed approach is often the most efficient.

✔ Evaluate current performance metrics

Record baseline metrics now. After migration, you’ll compare AWS performance improvements and cost changes.

✔ Choose your migration window

A zero-downtime move requires careful scheduling—usually nights, weekends, or slow traffic hours.

2. Cost Planning & Budget Forecasting

Cloud migration is not just a technical shift—it’s a financial one.

✔ Estimate AWS cost before migration

Use AWS Pricing Calculator to predict VM, storage, bandwidth, and managed services cost.

✔ Identify opportunities for early optimization

Even during migration, you can use cost-saving strategies like:

  • Rightsizing EC2

  • Using Spot Instances for non-critical tasks

  • Migrating storage into S3 Glacier for cold data

✔ Calculate data transfer costs

Large data migrations (terabytes) can incur serious transfer fees. Explore:

  • AWS Snowball

  • AWS DataSync

  • S3 Transfer Acceleration



3. Choose Your AWS Cloud Migration Strategy (The 7 Rs)

AWS famously offers 7 migration strategies—but the two most common for speed and zero downtime are:

1. Lift and Shift Migration (Rehost)

You move workloads as-is, with minimal changes. Fastest, simplest, and perfect for early migration phases.

2. Replatform or Refactor

You upgrade parts of your app while moving it—for example:

  • Moving to RDS instead of self-managed MySQL

  • Moving to ECS/EKS instead of EC2

Most teams use a combination of both based on complexity.

4. Set Up Your AWS Landing Zone

A secure, scalable foundation is mandatory before apps move.

✔ Create AWS accounts with proper structure

Use AWS Organizations to separate:

  • Production

  • Development

  • Testing

  • Shared services

✔ Configure IAM roles and least-privilege access

Who can deploy? Who can manage billing? Who can touch S3?Define everything early.

✔ Networking Setup (VPC, Subnets, Routing)

Set up:

  • Public + private subnets

  • NAT gateway

  • Internet gateway

  • VPC peering or Transit Gateway

✔ Security baseline

Configure:

  • Security groups

  • NACLs

  • AWS WAF

  • GuardDuty

  • CloudTrail

  • Encryption at rest & in transit

Thinking ahead now prevents major post-migration issues.

5. Data Migration Without Downtime

Data is the heart of your system—migrating it safely is the most critical part.

✔ Choose your data migration tool

  • AWS DMS → Real-time replication for zero downtime

  • AWS Snowball → Offline large data transfer

  • S3 Multipart Upload → For large unstructured data

✔ Set up continuous data sync

Run full load + CDC (Change Data Capture) to keep the destination DB synced until cutover.

✔ Validate data integrity

Check:

  • Record counts

  • Missing or corrupted data

  • Schema mismatches

Data verification often saves teams from post-migration panic.


AWS cloud migration

6. Application Migration: Safe and Controlled

Once data is synced, apps can move.

✔ Containerized apps → ECS/EKS

Perfect if your current stack already uses Docker.

✔ Virtual machines → AWS Server Migration Service (SMS)

For traditional VM-based apps that need full rehosting.

✔ Serverless → Lambda for event-driven workloads

✔ Set up CI/CD pipelines

Use:

  • AWS CodePipeline

  • GitHub Actions

  • GitLab CIThis ensures consistent, repeatable deployments.

7. Perform a Dry Run (Your Dress Rehearsal)

A zero-downtime migration requires practice before the actual cutover.

✔ Spin up a staging environment identical to production

Match:

  • Configurations

  • VPC

  • IAM

  • Storage

  • Networking

✔ Test load & performance

Use load testing tools to see if AWS can handle peak traffic.

✔ Run failover tests and rollback readiness

Know exactly what happens if you need to roll back.

✔ Validate logs & monitoring

CloudWatch, X-Ray, and OpenTelemetry should all be properly capturing data.

8. Cutover Plan: Achieve Zero Downtime

The moment of truth—your actual migration.

✔ Enable final data sync (CDC catch-up)

Ensure no writes are lost during the switch.

✔ Switch DNS using Route 53

Use weighted routing or blue-green deployment to switch traffic gradually.

✔ Monitor health checks and logs continuously

Watch:

  • 5xx error rates

  • Latency

  • Database performance

  • Application logs

✔ Keep rollback plan ready

If something breaks, you must be able to revert instantly.



9. Post-Migration Optimization

Your migration isn’t complete until your AWS environment is fully optimized.

✔ Rightsize EC2 instances

Most teams over-provision during migration—now is the time to reduce waste.

✔ Switch to managed services

Move databases to RDS, caching to ElastiCache, file storage to EFS/S3.

✔ Implement autoscaling

Scale up during peak hours, scale down automatically to save money.

✔ Review security posture

Enable:

  • CloudTrail

  • Config Rules

  • IAM Access Analyzer

  • WAF

  • Shield Advanced (if needed)

✔ Continuous cost monitoring

Cloud costs can skyrocket silently if not monitored.

Tools like AWS Cost Explorer provide visibility, but third-party or automation-driven solutions give more control.


A complete AWS cloud migration checklist covering lift and shift migration steps, zero-downtime planning, and a full migrate to AWS guide for smooth transitions.


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