Moving from on-premise infrastructure to the cloud is one of the highest-risk IT projects a business can undertake, because the window for error is narrow and the consequences of a poorly planned migration are visible to everyone.

Downtime during a migration can quickly become a business orders, if orders do not get processed, staff cannot access systems, or customers experience failures. Here’s how you can prevent those failures.

Phase 1: Discovery and Assessment

No migration should begin without a complete inventory of what exists.

• Document every application, database, and service running on-premise, including version numbers, dependencies, and the teams that depend on them
• Identify which workloads are migration-ready and which require remediation first
• Map all integrations and data flows between systems so that nothing is discovered mid-migration
• Assess current infrastructure performance baselines so the cloud environment can be sized appropriately
• Identify data classification requirements: what data is sensitive, regulated, or subject to residency requirements
• Document current backup and recovery procedures so they can be replicated or improved in the new environment

Phase 2: Architecture and Planning

• Select the target cloud environment based on workload requirements, not default vendor preference
• Define the migration approach for each workload: lift-and-shift, re-platform, or re-architect
• Design the network topology for the cloud environment including segmentation, access controls, and connectivity back to any remaining on-premise systems
• Define identity and access management for the new environment before migration begins
• Set performance and availability targets for each migrated workload and confirm the target environment can meet them
• Establish a naming and tagging convention so that costs and ownership are clear from day one
• Define a rollback plan for each workload in the event the migration fails or performance is unacceptable

Phase 3: Pre-Migration Preparation

• Communicate the migration schedule to all affected teams with enough lead time for them to plan around it
• Identify and contact all third-party vendors whose integrations will be affected and confirm their readiness
• Create a complete backup of all systems being migrated and verify the restore process works
• Set up monitoring and alerting in the target environment before workloads are moved
• Establish a migration runbook: a step-by-step operational guide for each workload being moved
• Assign clear ownership for each workload during migration, including who makes the go or no-go decision at each checkpoint
• Define communication protocols for the migration window: who is informed of progress, who is notified of issues, and how decisions are escalated

Phase 4: The Migration Window

• Begin with lower-risk, non-critical workloads to validate the process before moving business-critical systems
• Follow the runbook for each workload without improvising unless a specific issue requires it
• Validate each migrated workload against the defined performance and functionality checklist before proceeding to the next
• Keep the on-premise environment intact and operational until validation is complete, not until migration is complete
• Log every action taken during the migration window so that issues can be traced and reviewed afterward
• Maintain a clear record of what has been migrated, what is in progress, and what remains

Phase 5: Post-Migration Validation

• Test every application and integration in the new environment against a defined acceptance criteria list
• Confirm that backup and recovery procedures are operational in the cloud environment
• Verify that monitoring and alerting are functioning as configured
• Conduct a performance comparison between the pre-migration baseline and the cloud environment
• Review access permissions to confirm that only appropriate users have access to each migrated system
• Decommission on-premise resources only after validation is complete and a defined stabilization period has passed
• Conduct a post-migration review to document what went well, what did not, and what should be done differently in future migrations

This Checklist Is Your Insurance Policy

Although the checklist above does not guarantee a perfect migration, it does guarantee that when something unexpected happens, the team has the information and the structure to respond without making the situation worse.

At Smartt, we manage cloud migrations for organizations that cannot afford downtime and do not have the internal capacity to run a migration of this complexity alongside everything else. FlexHours gives you structured cross-disciplinary migration support along with discounts and credits on hosting and hardware purchases for hybrid clouds. If a migration is on your roadmap, reach out before the planning stage!