The verdict in three sentences
A failed migration costs more than the software itself: 5 to 15 % errors when copying by hand, duplicates and wrong balances. The key isn't the import, it's the upstream cleaning and mapping, then a parallel control run to compare old and new before cutting over. Expect 1 to 4 weeks and 500,000 to 2,500,000 FCFA depending on volume and data messiness.
The 5 steps of a clean migration
A migration isn't a copy-paste. Each step reduces the risk of loss or duplication.
| Step | Goal | Risk if rushed | Share of effort |
|---|---|---|---|
| Extraction | get all data out of the source | forgotten data | 10 % |
| Cleaning / dedup | fix formats, remove duplicates | duplicates, wrong balances | 35 % |
| Field mapping | align old and new model | lost fields | 25 % |
| Import | load into the new app | crash, truncation | 10 % |
| Control / parallel run | compare totals and samples | unseen errors | 20 % |
Cleaning and mapping alone account for 60 % of the work: that's normal, that's where final quality is won.
Manual vs automated: what changes
Re-typing by hand looks free, but the error rate makes it expensive past a few thousand rows.
| Criterion | Manual migration | Automated migration (script) |
|---|---|---|
| Error rate | 5-15 % | < 1 % |
| Time for 10,000 rows | 2-4 weeks | 2-5 days |
| Cost | hidden internal time | 500,000-2,500,000 FCFA |
| Reproducibility | none | replayable at will |
| Totals control | hard | automatic |
| Cutover risk | high | controlled |
Automation has another decisive advantage: you can replay the migration as many times as needed on a test environment before the real cutover.
Cutover checklist
- Freeze entries in the old system on D-day.
- Check totals: record count, sum of amounts, customer/supplier balances.
- Sample 30 to 50 random records and compare them line by line.
- Parallel run: run old and new side by side for a few days.
- Rollback plan: keep a complete usable backup.
- Sign-off by a business owner before switching off the old system.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Mariam manages a wholesaler in Dakar on an old software and three Excel files: about 12,000 items and 3,500 customers. A manual entry estimated at 3 weeks would have left, at 8 % error, nearly 1,240 wrong records to fix afterward. With a scripted migration at 1,400,000 FCFA, cleaning removes 600 duplicates, mapping aligns categories, and the parallel run shows totals matching 100 %. Cutover succeeds in 9 days, without paralyzing operations, and zero wrong customer balance at launch.
FAQ
How long does a migration take?
From 1 week for a few thousand clean rows to 4 weeks for large, messy data. Cleaning is what stretches the timeline most, not the import.
Why not just re-type by hand?
Because the error rate hits 5 to 15 %. On 10,000 rows that's hundreds of wrong records, often found too late, after the cutover.
How much does it cost?
From 500,000 FCFA for a simple migration to 2,500,000 FCFA for complex data needing heavy cleaning and several sources merged.
How can I be sure nothing is lost?
Through totals control (record count, sum of amounts) and a sample of 30-50 records compared line by line, plus a parallel run before switching off the old system.
Can I roll back if it fails?
Yes, provided you froze the old system and kept a complete usable backup. That's why you never delete the source before business sign-off.
Let's talk about your project. We audit your legacy data and deliver a scripted, controlled, loss-free migration. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
