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Zero-downtime IT system migration

An acquisition, a merger or an ageing information system to replace: I migrate your customers, technologies and data to the target system, in ordered steps, without interrupting service for the people who depend on it.

Describe my situation

When this service helps

An acquisition to absorb
One company has bought another and has to merge two information systems, bringing customers, products and billing into a single one.
A monolith to replace
An old system that is hard to evolve must give way to a modern architecture without stopping the business.
A platform to change
Customers, products and invoices must move to a new platform without asking users to do anything complicated.

The method in five steps

Each step prepares the next. The order starts from the customer and their contract and ends on the infrastructure. The method comes from my assignment at Celeste, generalised to other systems.

  1. 1Administrative migration

    Bring customers into the target system.

  2. 2Access or service migration

    Take over what each customer uses, access by access or service by service.

  3. 3Catalogue mapping

    Build with the business teams the matrix that links each source product to its equivalent in the target system.

  4. 4Billing migration

    Move billing to the target system, checking that it does not diverge from the old one.

  5. 5Cutover

    Switch to the new infrastructure while preserving service. The aim is that the user has nothing complicated to do.

The risks the method covers

A service interruption
For customers who depend on the system, an interruption has an immediate cost. The order of the steps exists to avoid it.
A product with no equivalent
A product in the old catalogue that does not exist in the new one is spotted early, with the business teams, not on cutover day.
Diverging billing
The old and the new system must produce the same invoice for the same customer. This is checked before the cutover.

Scope

What I take on, and what stays on your side.

What I take on
Scoping and the order of the steps, building the migrations, the mapping matrix with your business teams and preparing the cutover.
What stays with you
Knowledge of your products and contracts, business decisions on the target catalogue, and sign-off on each step before moving to the next.

The proof

A completed migration, then one that is ongoing.

A ten-year-old monolith to replace

Star Croisières

Migration of a monolithic system to Laravel on AWS as microservices, during my four years as full-time CTO.

Read the project

An acquisition to absorb

Celeste

Migration of Stella Telecom's connectivity into Celeste, ongoing. The page describes the method, with no results.

Read the project

Common questions

Can you migrate without service interruption?
That is the aim of the method: ordered steps, ending with a cutover that preserves service. The exact level of risk is measured at scoping, system by system.
How long does a migration take?
It depends on the number of customers, products and systems involved. I do not give a duration before seeing your situation.
Do you work alone or with my team?
With your technical team and your business teams. The catalogue mapping matrix cannot be built without them.
What technology do you use?
I adapt to the target system. My main references are Laravel and PHP, with Docker and AWS depending on the case.