Define business success
Identify why you are migrating: modernization, consolidation, decommissioning or a platform change. Set measurable acceptance criteria, owners and dependencies.
Inventory more than storage volume
Count objects, versions, renditions and relationships. Identify custom types, metadata, permissions, inaccessible objects and source API constraints.
Agree content and security mappings
Decide how source fields, classifications, identities and ACLs map to the target. Record unsupported constructs and the agreed fallback representation.
Prove the difficult cases in a pilot
Include large files, deep hierarchies, unusual characters, many versions, compound objects and complex ACLs. Validate with content owners, not just technical teams.
Plan throughput and cutover
Measure export, transformation, import and validation rates. Include API throttling, network limits, staging storage, delta runs and any freeze period.
Define reconciliation and acceptance
Record expected and actual counts, integrity results, metadata checks, permissions tests and exceptions. Assign remediation owners and sign-off authority.
Separate migration from source retirement
Keep source retention, backups, legal holds, access, recovery and decommissioning approval in an explicit retirement plan. Retire only after agreed acceptance.