An AS400 hardware upgrade moves an IBM i workload to a different Power server. The IBM i operating-system release may change at the same time, but that is a separate compatibility decision. Start with the current machine, workloads, applications, and recovery evidence before choosing a Power 11 model or a cutover date.
Phase 1: Inventory the workload and its dependencies
Record the current machine type, IBM i release, partitions, processor and memory peaks, storage and I/O, batch windows, interfaces, third-party software, and support arrangements. Use representative performance data from the real business cycle rather than one quiet afternoon. The inventory should also show which applications cannot be unavailable together and who can verify them after a move.
Phase 2: Choose hardware with a model-level check
Power 11 has several model and configuration options. A model recommendation needs measured workload demand, growth expectations, IBM i entitlement, storage and I/O requirements, support terms, and a quote for the complete configuration. IBM's system-to-IBM i map is the starting point for release support by machine type. Compare the actual models in the portfolio Power 11 directory; do not treat one default server as the answer for every AS400 shop.
Phase 3: Plan the IBM i release separately
The target server's supported release and the source system's upgrade eligibility must both be checked. IBM i 7.6 requires Power 10 or later hardware, and IBM lists 7.4 and 7.5 as valid source releases for a 7.6 upgrade. Earlier releases need additional planning. The IBM i version upgrade planning guide sets out those gates, the required evidence, and the difference between a software install and a server refresh.
Phase 4: Prove the migration and recovery method
Choose a method that the source and target environments, media, applications, and licensed programs can support. IBM's installation and migration reference points to release-specific procedures. Test a recoverable system save, application restoration, interface reconnection, and acceptance checks on the intended target. Backup software can manage part of this work, but it cannot prove a cutover that was never rehearsed.
Phase 5: Measure the cutover instead of guessing it
Set the business-approved outage window from a rehearsal, not a generic weekend estimate. Document the sequence, owner, required media and keys, validation steps, rollback trigger, and observed recovery time. A disaster-recovery review belongs here because the new server changes what must be restored and in what order.
What the buyer should receive
A credible upgrade plan includes the workload inventory, model comparison, IBM i release decision, application and licensing checks, tested migration method, measured outage estimate, rollback conditions, and a configuration quote. The Power 11 pricing guide explains quote inputs. Bring the evidence to the sales conversation so the quote answers the actual environment, not an imagined average one.