Business software · 6 min read
Most data migrations fail for one boring reason: messy data
A practical software data migration checklist covering cleaning, mapping, testing and backup.
The short answer
Software data migration is the process of moving your records from an old system into a new one without losing or corrupting data. Done properly, it means cleaning the data first, mapping old fields to new ones, testing with a sample, and keeping a full backup of the original system until the new one is confirmed working.
By Raja Wahab, Co-founder, Fixby Studios · Published · Updated · 6 min read
Why data migration goes wrong
Most migration problems aren't technical failures; they're data quality problems that existed in the old system and got carried across. Duplicate customers, inconsistent formats and missing fields all cause issues once they land in a new, often stricter, system.
Software data migration checklist
- Export and review your current data: how many duplicates, blanks or inconsistent formats are there?
- Decide what genuinely needs migrating, and what can be archived instead.
- Map each old field to its new equivalent, and flag anything with no match.
- Agree who 'owns' the data decisions, such as which duplicate record is kept.
- Run a test migration with a small, anonymised sample first.
- Check the test results against the original records, field by field.
- Keep a full backup of the old system for an agreed period after go-live.
Full migration straight away
- — Higher risk of losing records
- — Mapping errors found late
Test migration first
- — Catches errors cheaply
- — Checked against original records
Testing before the full migration
Migrate a representative sample, including awkward edge cases like incomplete records or unusual characters, before committing the whole dataset. This catches most mapping errors cheaply, rather than discovering them after a full cutover.
“Clean and de-duplicate data before migrating, not after.”
A realistic migration timeline
| Stage | What happens |
|---|---|
| Audit | Review data quality and volume in the old system |
| Cleaning | Remove duplicates, fix formats, archive what's not needed |
| Mapping | Match old fields to new system fields |
| Test migration | Move a sample and check it manually |
| Full migration | Move the complete dataset, usually out of hours |
| Verification | Spot-check records in the new system against the old |
Data protection during migration
If personal data is involved, make sure it's handled securely in transit and at rest, and that you're not retaining more than necessary in temporary export files. The ICO's guidance on data minimisation is a useful reference here.
Sources
Your questions
- What is software data migration?
- It's the process of moving your records from an old system to a new one, including cleaning, mapping and testing the data so nothing important is lost or corrupted.
- How long does data migration take?
- It depends on data volume and quality. A small, clean dataset might migrate in a day; a large or messy one can take weeks once cleaning and testing are included.
- Should I clean data before or after migrating?
- Before. Migrating messy data into a new system just moves the problem and can make it harder to fix once staff rely on the new records.
- What if some old data has no matching field in the new system?
- Flag it early. You may need a custom field, an archive export, or a decision that it genuinely isn't needed going forward.
Raja Wahab is co-founder of Fixby Studios, a Huddersfield studio building websites, SEO, social media and business software for small, owner-managed businesses across West Yorkshire.
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