Cloud Migration: Costs, Risks and Schedule

Cloud Migration: Costs, Risks and Schedule Plan realistically

Short: Cloud migration is on the agenda of many midsize IT departments.

Cloud migration is on the agenda of many midsize IT departments. Promises are known: lower operating costs, higher scalability, more modern development platforms. The reality is more differentiated.

Projects estimated at three months often last one year. Cost savings do not automatically adjust.

And whoever shifts legacy systems into the cloud without modernizing them gets the same problems with higher invoice.

This article gives a realistic grouping – for leaders who put facts instead of promises.

What cloud migration really means: The seven strategies

Short response: Cloud migration sounds easier than it is.

Who plans Cloud Migration. Costs, Risks and Schedule realistically from idea to rollout, will find cost calculator. Legacy-Modernization, Solution. Legacy abbau, Comparison. Monolith vs. Microservices.

This also covers legacy code analysis in 5 days suitable entry on our website.

Not all cloud migrations are the same. McKinsey and Gartner describe seven basic strategies (the "7 R's") that bring very different challenges and risks:

Strategy	Description	Exercise	Benefit
Retire	Remove application	Minimum	Cost saving by omission
Retain	On-Premise leave	Minimum	No change
Rehost (Lift & Shift)	Move VM to Cloud	Low	Operation Room to adapt
Relocate	Move container in cloud	Low–Means	Portability
Repurchase	Replace with SaaS solution	Medium	Modernization
Replatform	With small adjustments in Cloud	Medium–High	Partial modernization
Refactor/Re-architect	Developing for Cloud	High	Full Cloud Benefits

The most common beginners mistake: "We migrate into the cloud". Often means Rehost – but promises the benefits of Refactor.

This is the starting point for many disappointed cloud projects.

What a cloud migration really costs

The cost calculation of a cloud migration has two pages: migration costs and running cloud operating costs.

Some migration costs:

Cost block	Driver
Planning and Assessment	Inventory, Dependency Review, Target Architecture
Technical Migration	Rehosting, Replating or Refactoring per Application
Testing	Functional, integration, load and safety tests
Data migration	Volume, format, quality control
Parallel operation	Costs for old + new system during transfer
Unforeseen	Experience value: 20–30 % Buffer schedule

Orientation values for mid-sized firms:

• Rehost of 5–10 VMs: 20,000–60,000 €.
• Replatforming an average application: 50,000–150.000 €.
• Complete re-architecture of a business application: €150,000–500.000+.

Building cloud costs: The most common miscalculation

Many companies compare on-premise writedowns with cloud usage costs. That's wrong.

Compare the Total Cost of Ownership – including electricity, cooling, maintenance, space, hardware renewal, IT personnel for on-premise vs. cloud usage, support contracts, egress costs (move data from the cloud) and license adjustments.

Cloud can be cheaper – but not automatically.

Anyone who pushes an on-premise application into the cloud as a lift-&-shift and continues to run as before pays typically 20–40 % more than on-premise.

Hidden risks that make projects fail

Unknown dependencies. In grown IT landscapes there are more undocumented connections between systems than anyone suspected. A dependency review before migration is not a guarantee, but a duty.

Legacy systems without API.

Older applications that communicate directly at database level or use proprietary protocols cannot simply be moved to the cloud.

Legacy-Modernization is often a needed parallel path.

Data migration underestimates. Large amounts of data, poor data quality and complex transformations make data migration the often underestimated discipline.

Anyone who calculates "we copy the database" underestimates the cleaning, validation and reconstruction of relationships.

Compliance and privacy. Where are the cloud regions? What personal data are stored? GDPR needs, operating arrangements and industry regulation must be clarified before migration – not afterwards.

Network latency. Applications that responded very quickly on-premise with local database can become noticeably slower after cloud migration through network latencies – especially with high DB traffic.

Lock-in risk. Anyone who invests deeply in proprietary cloud services of a provider (AWS, Azure, GCP) restricts later options of change. Think about portability strategy from the beginning.

Realistic schedule: What happens when

A typical cloud migration schedule for a midsize company with 10–30 applications:

Phase 1: Assessment (4–8 weeks)

• Application inventory
• Dependency review
• Cost modelling (on-premise vs. Cloud)- Target architecture per application (strategy: Rehost / Replatform / Refactor).
• Migration priority

Phase 2: Pilot Migration (4–8 weeks)

• migrate 1–2 uncritical applications
• Establishing processes and tools
• School team
• Using experiences for the main rollout.

Phase 3: Main Migration (3–12 months)

• Prioritized applications migrate into waves.
• parallel operation and acceptance tests.
• Turn off old systems

Phase 4: Optimization (running)

• Improve costs (Rightsizing, Reserved Instances).
• Improve monitoring and alerting
• Strengthen security architecture

Total project for a typical midsize company: 8–18 months, realistic rather at the top when legacy systems are affected.

Cloud Migration and Software Development

Short: Anyone who also modernizes applications or develops new applications during a cloud migration should coordinate the projects – not as separate silos.

Anyone who also modernizes applications or develops new applications during a cloud migration should coordinate the projects – not as separate silos. Individual software development to make cloud-native (container, microservices, infrastructure-as-code) pays off in the long term.

However, initially costs more.

New interface development is often needed to connect on-premise systems that run parallel to cloud-based applications. This integration layer is often underestimated.

Conclusion

Cloud migration is worthwhile if it is planned with realistic effort, clear strategy and matching timing.

Lift-&-Shift is the fastest way to the cloud, but brings the least benefits. Re-architecture is complex, but provides the greatest savings and room to adapt gains in the long term.

Our team accompanies cloud migration projects from hosting and cloud consulting through technical rollout to cloud migration – with the claim that in the end not only the systems are running in the cloud.

However, the operation is more efficient than before.

Frequently Asked Questions (FAQ)

Which cloud provider is the right one for German mid-sized businesses?

AWS, Azure and GCP provide all German data centers. Important are: existing Microsoft licensing (speaks for Azure), existing developer expertise, specific services and compliance needs.

There is no universally correct answer.

Do you have to go completely into the cloud, or are there alternatives?

Hybrid cloud architectures – part on-premise, part cloud – are the pragmatic solution for many midsize companies.

Not everything has to go to the cloud, just what it benefits.

What about GDPR and cloud?

All three major cloud providers have EU data protection guarantees (SCC, data processing agreements) and EU regions.

With especially sensitive data, a German data center or a sovereign cloud option (e.g. GAIA-X-compatible provider) can be useful.

Can we continue working during migration?

Yes – with parallel operation and phase shift. A big boom change (all at once) is almost always too risky for productive systems.

Stepwise migration with fallback option is standard.

Technical sources and further links

The following separate references complement the grouping on the topics of this Article:

• Bitkom – Digital Economy Association.
• BSI – Federal Office for Information Security.
• European Commission – Digital Strategy.
• MDN Web Docs (Mozilla)
• W3C – World Wide Web Consortium.

"APIs are the backbone of modern software: If you stabilize interfaces late, you will pay with double integration work."

— *Björn Groenewold, Managing Director, Groenewold IT Solutions *