# Move off the warehouse without a Friday night

> Snowflake, Synapse, Teradata or SQL Server onto Databricks, in validated waves, with a cutover that has a tested way back.

Canonical: https://www.techfabric.com/solutions/warehouse-migration

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## The conversion is the part everybody plans for

It is also the part that goes fine. What sinks a migration is the six months afterwards.

### Nobody can say what was in scope

The inventory was a spreadsheet taken in March by somebody who has since left, and three objects nobody counted are still running.

### The cutover has no reverse

Which is why it is scheduled for a Friday night. A plan with no way back can only run in a window where being wrong is survivable.

### The old platform stays on

Decommissioning is nobody's funded phase, so both bills run for a year and the migration has not saved anything yet.

None of that is conversion. It is record-keeping, and a migration that keeps its own records answers all three without anybody being asked to remember.

## What we install

### Two weeks, fixed fee

A Migration Readiness Sprint. What the estate contains, what converts cleanly, what will fight back, and a sequence with a number against it.

### A pilot subject area

One real workload moved end to end and validated, so the estimate for everything else stops being a guess.

### Waves, not a big bang

The estate moves in sequenced waves, each validated and each reversible, and the business keeps running throughout.

### Evidence per object

Signed migration certificates recording what converted, by which tool version, and what validation said.

### Governance carried across

Grants and lineage designed in Unity Catalog as part of the move rather than reconstructed afterwards from what the old system implied.

### Decommissioning

Turning the old platform off is in the plan, because it is the phase that decides whether any of this saved money.

## Twenty-seven source platforms

Airlift exists because we ran these migrations by hand first, and the parts that hurt are the parts it now handles. It is free and open source and it runs in your own workspace.

## Questions

### How long does it take?

Nobody can tell you before the assessment, and a firm that quotes a duration on a first call is guessing. What is fixed is the assessment: two weeks, fixed fee, ending in a sequence and a number.

### What happens if the cutover goes wrong?

You go back. The reverse path has been tested rather than documented, which is why these do not have to happen on a Friday night.

### Can we keep running the old platform in parallel?

For a period, and it is usually the right call. What matters is that turning it off is a dated phase rather than an intention, because otherwise it does not happen.