Migration checks and Exit Guides

MIGRATION  Guides.    

For uor clients we have templates and guides that we have used sucessfully on programmes and projects. Here are some extracts.

 

Exiting a Legacy Physical Data Centre" The basics "

Successfully exiting a data centre involves deciding what to do with each application, system, or service currently hosted in that facility. 

The 7 R’s framework offers strategic options for these decisions, which can help inform decommissioning, migration, or transformation plans.

Classification & Weighting

Each “R” is classified based on:

  • Complexity: (Simple, Moderate, Complex)

  • Typical Weighting (0–10): Based on effort, resources, and risk typically associated.

Strategy Summary Complexity Suggested Weighting (Effort/Complexity)
1. Retire Shut down the application completely. Used when systems are obsolete, duplicated, or no longer add value. Simple 2
2. Retain Keep the system as-is, potentially in the same data centre or in a “cocoon” environment. Typically used for niche systems with long lifespans. Simple 3
3. Rehost "Lift and shift" to the cloud or another hosted infrastructure. No application changes. Moderate 5
4. Replatform Move with some optimizations (e.g., upgrading OS/database). Minimal code change but adds some modernization. Moderate 6
5. Refactor Rewrite portions of the application to better fit a cloud-native architecture (e.g., microservices). Complex 8
6. Re-architect Substantial redesign to take full advantage of new infrastructure paradigms, often cloud-native. High cost but long-term value. Complex 9
7. Replace Fully swap the application with a new SaaS product or commercial off-the-shelf solution. Often expensive but fast-tracks modernization. Moderate–Complex 7

 

 

 

Data Centre Exit to Cloud: Best-Practice

the basics

Objective:

Exit physical DC lease without service interruption, data loss, or surprise cost overruns — by migrating all workloads off-premises into a fit-for-purpose cloud estate

 

Phased Approach (With Key Activities)

1. Discovery & Assessment (Baseline Everything)

“You can’t migrate what you don’t fully understand.”

  • Asset Inventory: Servers, storage, network gear, workloads, apps, integrations, data flows.

  • Application Mapping: Dependencies, uptime needs, data sensitivity, regulatory requirements.

  • Technical Debt Check: Legacy OS, unsupported hardware, hardcoded IPs, licensing traps.

  • Classify Workloads: By criticality, complexity, cloud readiness (Retire, Rehost, Refactor etc).

External Skills Needed:

  • Enterprise architects

  • Infrastructure & network specialists

  • Cloud solution consultants (Azure-specific expertise)

  • Application SME(s) for complex / in-house software

2. Strategy & Roadmap Design

“Not every workload is cloud-ready, and not all cloud is cost-effective.”

  • Apply the 7Rs (Retire, Retain, Rehost, Replatform, Refactor, Repurchase, Relocate)

  • Design target state architecture (landing zones, identity, network, security)

  • Build migration waves by priority, dependency, and risk

  • Define data migration & backup strategy (include rollback)

  • Define compliance and regulatory requirements (e.g., GDPR, ISO, PCI SOX HMRC IRS and more)

 

External Skills check-

  • Cloud architects

  • Security & compliance consultants

  • FinOps/Cloud cost modelling experts

  • Programme manager with cloud migration experience

3. Build & Prepare (Cloud Foundation & Readiness)

“Move fast, but build slow. Mistakes here echo loudly.”

  • Set up cloud landing zones (security, IAM, resource groups, logging)

  • Network design and hybrid connectivity (ExpressRoute / VPNs)

  • Pre-staging resources (storage, compute, backups)

  • Run pilot migrations to validate tooling and process

 

External Skills Check

  • Azure engineers DBA's etc.

  • Network/security engineers

  • CI/CD & infrastructure automation (DevOps)if you're going that far...

4. Migrate & Transform

“Do it once. Do it clean.”  or measure twice cut once... or really understand what it is you are moving

  • Execute migration waves with rollback plans

  • Monitor in real time, validate post-move performance

  • Tweak performance, reconfigure for cloud cost optimisation

  • Update documentation and support runbooks

  • Conduct security hardening post-migration

 

External Skills Check

  • Migration tooling experts (e.g., Azure Migrate, ASR)

  • Database admins (for SQL / Oracle / NoSQL)

  • Cloud-native engineers (to refactor apps if needed)

  • Operational support teams (ITSM alignment)

5. Decommission & Lease Exit

“No ghosts left behind. No license left active.”

  • Fully decommission infrastructure (secure data wipe, return leased kit)

  • Validate data sovereignty compliance

  • Final reporting & sign-off

  • Update asset and CMDB records if you don't have it then that's more work

  • Close down the lease (remove circuits, power, contracts) and telecoms T1 etc....

 

External Skills Check

  • Decommissioning specialists

  • IT kit Re use there could be some big value here...

  • Data destruction/certification service provider

  • Legal/contract advisory (esp. for landlord terms)

 

Peter Maher Ltd has managed this for enterprise clients delivered all of this and more...

 

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