What is a cloud migration assessment, and what key factors should you evaluate when determining how to migrate an application?

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A cloud migration assessment is a systematic evaluation of an organization's application portfolio to determine which applications should be migrated, how they should be migrated, and in what order. This assessment phase is critical because it directly impacts the success, cost, and timeline of the entire migration program.

The assessment starts with application discovery and inventory. You need a complete picture of what applications exist, where they run, and what resources they consume. Tools like AWS Application Discovery Service, Azure Migrate, and third-party solutions like Cloudamize and Flexera scan your on-premises environment to automatically discover servers, applications, and their resource utilization. This inventory typically reveals applications the organization had forgotten about, providing an opportunity for consolidation and retirement.

Dependency mapping is one of the most valuable outputs of the assessment. Understanding which applications communicate with each other, which databases they connect to, and which external services they depend on is essential for planning migration waves. An application that depends on five other services cannot be migrated independently. Dependency mapping tools analyze network traffic to build a visual map of application interdependencies. This map determines which applications must be migrated together as a group.

Technical complexity evaluation examines factors that affect migration difficulty. These include the operating system and version, which affects cloud compatibility. The programming language and framework version matter because some older technologies have limited cloud support. Licensing models for commercial software need evaluation since some licenses do not permit cloud deployment. Custom hardware dependencies like specialized network cards or GPU requirements limit migration options. Data volumes and database sizes affect migration timelines and data transfer costs.

Business criticality assessment ranks applications by their importance to the organization. Tier one applications are mission-critical systems where any downtime has significant financial or reputational impact. Tier two applications are important but can tolerate brief outages. Tier three applications are non-critical tools. This ranking determines the level of planning, testing, and risk mitigation required for each migration.

Performance baseline establishment captures current application performance metrics before migration. Response times, throughput, error rates, and resource utilization provide benchmarks against which post-migration performance can be compared. Without these baselines, it is impossible to verify that the migrated application performs at least as well as the original.

Compliance and regulatory requirements must be documented. Applications handling personal data, financial information, or health records may have specific requirements about data residency, encryption, and access controls that constrain cloud deployment options.

The assessment output is typically a migration plan that groups applications into waves based on dependencies, assigns a migration strategy from the 6R framework to each application, estimates the effort, cost, and timeline for each wave, and identifies risks and mitigation plans. This plan becomes the roadmap for the entire migration program.