Cloud Migration Services: Strategies, Timeline, and What It Actually Costs

Cloud migration is not a single project — it is a programme of work that can take months to years depending on the complexity of the existing estate. Companies that treat it as a one-time "move everything" project typically underestimate cost, overrun timelines, and end up with cloud infrastructure that costs more than their on-premise equivalent.

The 6 Rs of Cloud Migration

Every workload has a migration strategy. AWS popularised the 6Rs framework:

Most large migrations use a mix: lift-and-shift first for speed, then refactor high-value workloads over time.

Migration Sequence

Phase 1: Discovery and Assessment (2–4 weeks)
├── Inventory all workloads
├── Map dependencies between systems  
├── Classify by migration strategy (6Rs)
└── Identify quick wins (retire/retain decisions)

Phase 2: Foundation (4–8 weeks)
├── Set up landing zone (VPC, accounts, IAM)
├── Establish networking (VPN/Direct Connect)
├── Set up monitoring and logging baseline
└── Deploy CI/CD pipeline for migrated workloads

Phase 3: Wave 1 — Low-risk workloads (4–8 weeks)
├── Dev/test environments first
├── Stateless web applications
└── Validate runbooks and automation

Phase 4: Wave 2 — Production workloads (8–20 weeks)
├── Databases (most complex, highest risk)
├── Business-critical applications
└── Cutover with rollback plan

Phase 5: Optimisation (ongoing)
├── Right-sizing instances
├── Reserved instance purchases
└── Refactoring for cloud-native services

Database Migration (The Hard Part)

Database migration is where most cloud migrations hit problems. Schema changes, compatibility issues, downtime requirements, and data integrity validation are all non-trivial.

# AWS DMS (Database Migration Service) — continuous replication approach
# 1. Set up source and target endpoints
# 2. Create replication instance
# 3. Run full load + CDC (Change Data Capture) for near-zero downtime

# Zero-downtime cutover sequence:
# 1. Start DMS replication (full load + ongoing CDC)
# 2. Verify replication lag < 1 second
# 3. Put application in read-only mode (1-2 minute window)
# 4. Wait for replication to catch up completely
# 5. Update connection strings
# 6. Restore read-write mode
# 7. Monitor for 30 minutes
# 8. Stop DMS replication

Cost Expectations

Infrastructure cost changes: typically neutral to slightly higher initially (lift-and-shift), 20-40% lower after optimisation (right-sizing, reserved instances, architectural improvements).

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Planning a cloud migration? Viprasol handles cloud migrations with zero-downtime cutover plans. Contact us.

See also: AWS Development Services · DevOps Consulting Company Guide