Why Hybrid & Phased Migration?
Most enterprises cannot migrate everything to Azure in a single cutover. Dependencies, compliance requirements, and downtime concerns demand a hybrid or phased strategy. This allows workloads to be migrated gradually while keeping critical services online.
Hybrid Migration Approaches
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Hybrid Cloud (On-Prem + Azure)
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Workloads run across both environments.
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On-premises Active Directory synced with Entra ID.
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Hybrid networking via VPN/ExpressRoute.
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Used when apps cannot be moved fully due to compliance or latency.
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Hybrid Identity
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Use Azure AD Connect / Entra Connect for synchronization.
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Enables SSO for apps still running on-premises.
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Supports staged migrations (users and groups moved gradually).
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Hybrid Storage
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Azure File Sync keeps on-prem file servers in sync with Azure Files.
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Cached copies locally, full dataset in Azure.
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Useful for branch office workloads.
Phased Migration Approaches
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Pilot/Canary Migration
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Migrate small subset of workloads first.
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Validate performance, security, and cost.
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Expand gradually after success.
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Parallel Run
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Run workloads in both environments temporarily.
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Validate that Azure system behaves as expected before decommissioning legacy.
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Big-Bang vs Phased
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Big-Bang: move everything in one cutover (risk of downtime).
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Phased: migrate in waves (less risk, but longer duration).
Supporting Tools
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Azure Migrate → for discovery & phased execution.
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Azure Site Recovery (ASR) → for near-zero downtime cutovers.
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ExpressRoute/VPN Gateway → hybrid connectivity.
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Azure Arc → extend governance & security to on-prem workloads.
Example Enterprise Scenario
A government agency requires:
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Legacy ERP cannot be migrated immediately due to compliance.
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Customer portal must move to Azure App Service quickly.
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File shares must remain accessible on-prem for branch offices.
Correct design:
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Keep ERP system on-prem but extend governance with Azure Arc.
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Migrate customer portal in Phase 1.
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Enable Azure File Sync for hybrid file storage.
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Use ExpressRoute for secure, low-latency hybrid connectivity.
Confusion Buster
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Hybrid Cloud vs Multi-Cloud
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Hybrid = Azure + on-prem.
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Multi-cloud = Azure + AWS + GCP, etc.
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Azure Arc vs ASR
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Arc = governance/management for hybrid.
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ASR = replication/failover for migration/DR.
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Pilot vs Parallel Run
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Pilot = small subset testing.
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Parallel = full workload duplication in both environments.
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Exam Tips
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“Which service extends Azure governance to on-prem workloads?” → Azure Arc.
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“Which tool replicates workloads for near-zero downtime migration?” → ASR.
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“Which service keeps on-prem file servers synced with Azure Files?” → Azure File Sync.
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“Which migration approach reduces risk by moving workloads in waves?” → Phased migration.
What to Expect in the Exam
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Direct Q: “Which Azure service provides hybrid governance for on-prem workloads?” → Azure Arc.
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Scenario Q: “Agency must migrate workloads gradually due to compliance.” → Phased migration with Azure Migrate.
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Scenario Q: “Branch office must keep local file access but use Azure for central storage.” → Azure File Sync.
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Trick Q: “Hybrid and multi-cloud are the same.” → False.