Exit an IBM Z mainframe and target Azure incrementally.

Modernization is delivered in successive functional waves rather than on a monolithic plan: the cadence is set at scoping based on volume and criticality. Non-critical transactions are migrated first, critical transactions (payments, central accounting) last. The mainframe-Azure coexistence lasts the entire duration of the program. The objective is total mainframe decommissioning at the end, not just lightening it.

Yes, this is rehosting on emulator (Micro Focus Enterprise Server, TmaxSoft OpenFrame). The COBOL code runs on Azure VMs. Pros: fast migration, low initial effort, preservation of existing code. Cons: no real modernization (technical debt preserved), dependency on a third-party vendor, often high emulator license costs. We see this approach as a temporary stepping stone useful to quickly exit IBM hardware, but not as a final target. True modernization comes in a second phase with rewriting to Java, .NET Core, or TypeScript.

It is a useful accelerator but not a turnkey solution. Azure Mainframe Migration offers analysis tools, partnerships (Micro Focus, Raincode, Astadia, TmaxSoft), and managed services suited to mainframe workloads. These tools can convert COBOL to Java or .NET automatically, but exiting the mainframe still requires significant characterization, parity audit, and refactoring work. Our ATLAS methodology integrates these tools as accelerators where relevant, without treating them as an end in themselves.

Azure offers native elasticity that the mainframe cannot match at this price point. Month-end peaks are absorbed by AKS or App Service auto-scaling, scaling up automatically and down in lulls. The annual accounting close can be handled by a temporary dedicated cluster. This elasticity generates significant savings compared to a mainframe sized for the peak and underutilized the rest of the time. Typical saving: 30 to 50 percent on TCO over a 3-year horizon after complete modernization.

A mainframe exit budget is driven by estate size (often one to ten million lines of COBOL) and above all by the chosen trajectory, which changes the order of magnitude entirely. We do not price a mainframe from declarations: the ATLAS Intake establishes the real inventory of programs, JCL chains and CICS transaction boundaries before any commitment. Free initial scoping call, 30 minutes to 2 hours.

Three major risks: organizational fatigue (teams tire on a long program), change of executive priorities (budget, strategy), target technology obsolescence (target technologies evolve over five years). Mitigations: contractual milestones to validate each step, incremental deliveries with visible business value each year, modular target architecture that can be revised without questioning the foundations. Our experience: programs that deliver visible value each year succeed, those that promise a five-year big-bang drift.

It depends on the migration strategy and the scope. Three trajectories with very different cost profiles: lift-and-shift (rehost on Azure VMs running an emulator), fastest but keeps the debt; replatform (move to Azure SQL, App Service, Container Apps while keeping most of the code); and refactor (cloud-native microservices modernization), longest but the only one that truly removes the dependency. The trajectory choice, made at the end of Intake, weighs more on budget than estate size. Free initial scoping call, 30 minutes to 2 hours.