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Data Engineering

Data Migration Services

Move data between databases, applications and clouds with complete reconciliation, rehearsed cutovers and a tested rollback plan, so the business never loses trust in its records.

Move Your Data Without Losing Accuracy or Momentum

Every ERP replacement, CRM consolidation, cloud move or merger depends on data migration, and it is often the part that causes delays. Source systems hold undocumented fields, years of workarounds and duplicate records, while target systems enforce stricter rules. Moving data successfully means understanding what it actually contains, transforming it correctly and proving that nothing was lost or changed along the way.

Hanoi Technology runs data migration as an engineering discipline. We profile source data, document mapping rules with business owners, build repeatable and automated migration pipelines, reconcile every load against the source and rehearse cutover until it is routine. You get measurable evidence of accuracy, not a promise.

The Challenge

Where Data Migrations Go Wrong

Most failed migrations share a small number of root causes.

Poorly Understood Source Data

Fields are reused for other purposes, codes change meaning over time and business rules live in people’s heads. Surprises appear late, when they are most expensive to fix.

Hidden Dependencies

Interfaces, reports and batch jobs still point at the old system. A migration can pass isolated tests and still break real processes on day one.

Validation Squeezed by Deadlines

When schedules slip, testing and reconciliation are cut first. Silent errors, such as truncated values or wrong mappings, then reach production undetected.

No Rehearsed Cutover or Rollback

A cutover executed for the first time on go-live weekend, with no tested way back, turns a small issue into a business outage.

Business Value

What a Disciplined Migration Delivers

Provable Data Accuracy

Automated counts, checksums and value comparisons document that every record arrived intact. Auditors and business owners sign off on evidence.

Minimal Downtime

Incremental loads and change data capture keep the target in sync, so the final cutover window is hours rather than days.

Cleaner Data in the New System

Duplicates, invalid values and obsolete records are resolved during migration rather than carried forward. The new platform starts with better data than the old one.

Predictable Go-Live

Multiple rehearsals with timed runbooks make cutover a known quantity. Go and no-go decisions are based on clear criteria.

Migration Is a Product with a Short Life, Built to Production Standards

Migration code runs only a few times, but each run must be correct. We build it with the same version control, automated testing and repeatability as any production pipeline, so the tenth rehearsal behaves exactly like the first and the final run holds no surprises.

Our Services

Hanoi Technology’s End-to-End Data Migration Services

Services covering every phase of a data migration program.

Migration Assessment and Strategy

We inventory sources, targets, volumes, interfaces and constraints, then recommend a big bang, phased or parallel-run approach with a clear rationale and risk register. We also confirm constraints such as blackout periods, regulatory deadlines and contract end dates for the legacy system.

  • Source and target inventory
  • Approach recommendation
  • Risk register and plan

Data Profiling and Quality Remediation

We profile real values to find nulls, duplicates, invalid codes and inconsistent formats, and agree remediation rules with data owners before mapping begins. Some issues are best fixed at the source before migration, others during transformation, and we document which is which.

  • Profiling report
  • Data quality issue log
  • Cleansing rules

Mapping and Transformation Design

We document field-level mappings, transformations, defaults and lookups in versioned specifications reviewed by business experts, including edge cases. Every rule is traceable to a requirement and an approver.

  • Source-to-target mapping specification
  • Transformation rules
  • Edge case catalog

Migration Pipeline Development

We build repeatable extract, transform and load pipelines using cloud-native services, ETL platforms or custom code, parameterized for test, rehearsal and production runs. Runs are idempotent, so a failed load can be restarted safely without creating duplicates.

  • Automated migration pipelines
  • Incremental and delta loads
  • Run logs and metrics

Reconciliation and Testing

We automate count, sum, checksum and sampled record comparisons, and support business acceptance testing of migrated data in the target application. Results are summarized in dashboards that business owners can review without technical help.

  • Reconciliation framework
  • Test evidence packs
  • Defect tracking

Cutover Planning and Execution

We write and rehearse a minute-by-minute runbook covering freeze, final sync, validation, go/no-go and rollback, then execute it with your team on go-live. Roles, communication channels and decision owners are agreed well before the cutover weekend.

  • Cutover runbook
  • Rehearsal reports
  • Hypercare support

Our Approach

Our Five-Phase Migration Method

Each phase produces evidence that the next one can safely begin.

  1. 01

    Discover and Inventory

    We catalog every table, file, interface and report that touches the data, with owners, volumes and whether each object moves, transforms or retires.

    Deliverables: Data inventory · Dependency map

  2. 02

    Profile and Plan

    We profile actual values, assess quality, choose the migration approach and define measurable acceptance criteria before any data moves.

    Deliverables: Profiling results · Acceptance criteria

  3. 03

    Design and Build

    We document mappings, build automated pipelines and reconciliation checks, and run them repeatedly against copies of production data.

    Deliverables: Mapping specifications · Migration and reconciliation code

  4. 04

    Test and Rehearse

    We run full dress rehearsals with timing, reconciliation and business validation, refining the runbook until results are consistent and within the window.

    Deliverables: Rehearsal reports · Final runbook

  5. 05

    Cut Over and Support

    We execute the cutover, validate results against the agreed criteria, make the go/no-go call with you, and provide hypercare as users start working in the new system.

    Deliverables: Go-live sign-off · Hypercare issue log · Decommissioning plan

Use Cases

Data Migration Scenarios

Typical migrations our teams plan and deliver.

ERP Replacement

Migrate customers, vendors, items, open orders and balances from a legacy ERP to a modern platform. Finance reconciles opening balances before go-live.

CRM Consolidation After a Merger

Combine two CRM instances with overlapping accounts and contacts. Matching and survivorship rules create one clean customer record.

Database Move to the Cloud

Migrate Oracle, SQL Server or MySQL databases to managed cloud databases. Change data capture keeps them in sync until a short cutover window.

Legacy Application Retirement

Extract data from a decommissioned system into an archive that remains searchable for compliance. License and hardware costs end while records stay accessible.

Warehouse and Lake Migration

Move historical analytical data to a new cloud platform with checksums for every table. Reports are validated against the old platform before switch-off.

SaaS Platform Switch

Move records, attachments and history between SaaS tools through their APIs. Rate limits and data relationships are handled without losing links.

Technology

Migration Tools and Platforms

We choose tooling by source, target and volume.

  • AWS Database Migration Service
  • Azure Database Migration Service
  • Google Database Migration Service
  • Debezium
  • Informatica
  • Azure Data Factory
  • AWS Glue
  • Apache Spark
  • dbt
  • Great Expectations
  • Oracle
  • SQL Server
  • PostgreSQL
  • SAP
  • Salesforce
  • Python

Platforms

Deliver Data Migration on Your Preferred Platform

Why Hanoi Technology

Why Organizations Choose Hanoi Technology

Senior, Cross-Functional Teams

Strategy, data, AI, cloud and engineering specialists work as one team, so nothing is lost between hand-offs.

Proven Delivery

More than 50 projects delivered for clients in North America, Europe and Asia-Pacific.

Radical Transparency

A written update every week and a demo of working software every sprint, so you always know where things stand.

Cost-Effective Global Delivery

Experienced engineers from our Hanoi delivery hub, with working-hour overlap for every major time zone.

+162%monthly active users

Success Story · Fintech

All-in-one digital banking app for a traditional bank

A traditional financial institution wanted to compete with neobanks for mobile-first customers. We replaced a set of separate banking, investing and payment apps with one product that people use every day.

Read the Full Story

More Success Stories

Explore All Success Stories

Resources

Featured Resources

Industry trends and practical guidance to help you get more value from data, AI and technology.

Plan a Migration You Can Prove Was Right

Tell us what you are moving, from where and by when. We will reply within 24 hours and arrange a free consultation to review scope, approach and key risks.

Data Migration FAQ

Should we choose a big bang or phased migration?

Big bang moves everything in one planned window. It is simpler but concentrates risk, so it suits smaller, well-understood datasets that can tolerate downtime. A phased or trickle approach moves data in batches while both systems stay live, which spreads risk but requires synchronization. A parallel run is the safest for regulated or high-stakes data but costs more. We recommend an approach based on your downtime tolerance, volumes and risk.

How do you prove that data was migrated correctly?

We define acceptance criteria before moving anything, then automate checks after every load: record counts per entity, sums of financial values, checksums of key columns and comparison of sampled records. Business users validate that reports and balances match in the target. All results are logged and packaged as evidence for sign-off and audit.

How much downtime will the cutover need?

It depends on volumes, the approach and how much data can be loaded in advance. By loading history early and using incremental loads or change data capture to keep the target current, the final window often covers only the last changes, validation and switching users. Rehearsals measure the real duration so the business can plan around it.

What if something goes wrong during cutover?

Every cutover has go/no-go checkpoints with clear criteria and a rehearsed rollback plan that keeps the source system recoverable. If validation fails, we either fix the issue within the window or roll back in a controlled way. Because rehearsals have exercised the runbook, the team knows what to do at each step.

Who needs to be involved from our side?

We need data owners or subject matter experts who understand what the data means, to review mappings and resolve quality issues, plus access to source and target environments and a business lead for acceptance testing. Their time is concentrated during mapping and testing. We send weekly written updates and run demos so stakeholders see progress without attending every meeting.

How do you protect sensitive data during migration?

Data moves over encrypted connections and is stored encrypted at rest. Development and test runs use masked or subset data wherever possible, access is limited to named team members and logged, and temporary staging areas are cleaned up after cutover. We follow your security and data residency policies and document all data flows for review.

Can you migrate data from systems with no documentation or support?

Yes, this is common with legacy applications. We reverse-engineer data structures by analyzing database schemas, application screens, reports and actual values, and we interview long-time users who understand how fields are really used. Where vendors no longer support the system, we extract data directly from the database or exports. Findings are documented as we go, so knowledge that existed only in people’s heads becomes part of the migration specification.

What happens to the old system after migration?

After a successful cutover and a hypercare period, the old system is typically set to read-only, archived or decommissioned according to your retention and compliance requirements. We help define what must be retained, in what format and for how long, and whether a searchable archive is needed for audits or legal holds. Decommissioning only happens once business owners confirm that nothing still depends on the old system.