VMware to Azure, without stopping the airline

01 — The challenge

Where it started.

The estate was a set of interdependent applications on VMware, supporting operations that do not stop. The hard part was never the individual move; it was what breaks when systems that talk to each other sit on different sides of the migration for a period.

Downtime had to be minimal, performance had to match the on-premise baseline, and compatibility between applications had to hold throughout.

02 — What we built

The work itself.

Azure Site Recovery. Virtual machines replicated ahead of cutover, so the switch is a short tested step rather than a copy performed under pressure.

Azure VMs and virtual networks. A target environment matched to the on-premise specification, so performance could be compared rather than hoped for.

ExpressRoute and site-to-site VPN. Secure routes between what had moved and what had not, which is what allows a migration to be staged at all.

Waves, each tested. A lift-and-shift ordered by dependency, with testing per wave rather than a single validation at the end.

03 — Results

What the client has now.

Downtime through the migration kept minimal, with critical services operational throughout. Application compatibility maintained across interdependent systems. Performance consistent with the on-premise specification. Hardware maintenance removed, with scalability and Azure’s security and compliance controls gained.