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We Are Scared of Losing Data if We Migrate. How Do We Do It Safely?

Fear of losing records keeps you on an old system. How SpiderHunts migrates data with repeatable scripts, reconciliation and a way back if something is wrong.

Updated 3 min readBy SpiderHunts Technologies

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Quick answer — TL;DR

A safe migration uses repeatable scripts rather than one-off exports, reconciles counts and sample records against the source, rehearses the move several times on copies, and keeps the old system readable afterwards. Data loss comes from skipping those steps, not from migrating.

Why the new system keeps getting postponed

Everyone agrees the old system should go. The new one has been chosen, or at least discussed. And the move keeps slipping, because every time it comes up someone asks the question nobody can answer: what if we lose something?

It is a reasonable fear. Maybe you have seen it happen. A previous migration left notes behind, dropped attachments, or turned every date into the American format. Customers rang about things the new system had no record of. People still open the old system to check history because they do not trust the new one.

Where data actually gets lost

Data rarely disappears in one dramatic failure. It leaks through small gaps that nobody checked.

GapWhat goes missing
Export does not include everythingNotes, attachments, history tables, custom fields
Field too short or wrong typeTruncated text, lost leading zeros, broken dates
No home in the new systemData with nowhere to go is quietly left behind
Character encodingAccented names and symbols turned to question marks
Relationships breakOrders no longer linked to their customer
Records change during the moveWork done on cutover day is lost

The common thread is that the migration was a single manual event: export, tidy in a spreadsheet, import, hope. When that is the method, nobody can say for sure what arrived.

What staying put costs

  • Continued licence and support fees for a system you have outgrown
  • Workarounds and spreadsheets around its limits
  • Risk growing each year as the old system ages
  • A new system paid for and not used, or used alongside the old one
  • Staff frustration with a tool everyone knows should have gone

Postponing does not reduce the risk. The data only grows, and the people who remember why things are the way they are gradually leave.

There is also a cost to the new system if it is already bought. A package that sits half set up, with a few enthusiasts using it alongside the old one, splits your records in two. Every month that goes on, the eventual migration has more to merge.

How we migrate

  1. Full extraction. We take the data from the source database itself where possible, not from a report or a partial export, including notes, attachments and history.
  2. Mapping document. Every source table and field is mapped to a destination, with a transformation rule if needed. Anything with no destination is listed, and you decide what happens to it, whether that is a custom field, an archive or a deliberate drop.
  3. Scripted migration. The move is a script that can be run again and again. That means we can rehearse it on copies, fix what is wrong and rerun it cleanly.
  4. Reconciliation. After every run we compare record counts per type, totals for money fields, and a sample of records checked field by field, including the awkward ones like long notes and unusual characters.
  5. User testing. Staff check records they know well in the new system and report anything that looks wrong.
  6. Cutover plan. A short freeze on the old system, a final delta migration for recent changes, a final reconciliation, then go live. A rollback plan is written in advance.
  7. Archive. The old system or a searchable copy of its data is kept read-only, so history can always be checked.

After the move

Staff work in the new system knowing the history is there, because they checked it during testing. If someone does find a gap, the mapping document and reconciliation reports show exactly what was moved, and the archive holds the original.

The fear goes because the unknowns were turned into lists and checked, not because anyone promised nothing would go wrong.

The scripts themselves remain useful too. If the business later merges with another, or adds a second system, the same mapping and reconciliation approach can be reused rather than worked out again from scratch.

Signs you are stuck here

  • A system change has been postponed more than once over data worries
  • A past migration lost notes, attachments or history
  • Nobody is sure what the old system holds beyond the main screens
  • Staff still open an old system to check history
  • The migration plan is an export into a spreadsheet

FAQ

Frequently asked questions

The questions readers ask us after this guide.

Still have a question?

Ask us directly — a senior engineer will get back to you.

Ask about your project

Can you promise nothing will be lost?

No honest supplier can promise that. What we can do is make every record accounted for: counted, sampled, mapped or deliberately excluded, with the old data kept readable.

What if our old system cannot export properly?

We go to the underlying database where we can. If that is not possible, we combine the exports that exist and check them against the screens.

How much downtime is involved?

It depends on data volume and the systems involved. Rehearsals tell us how long the final run takes, so the cutover window is planned from real timings.

Should we clean our data before migrating?

Some cleaning during migration makes sense, such as merging obvious duplicates. Large clean-ups are often better done afterwards so they do not delay the move.

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