The Dell PowerStore NDU process follows a specific internal orchestration sequence to ensure data availability. First, the Primary node (the orchestrator) is prepared (Step 1), followed by the Peer node (Step 2), which involves staging the upgrade packages. The Peer node is upgraded first (Step 3) while the Primary continues to serve I/O. The Commit step (Step 4) acts as a checkpoint to finalize the Peer's successful upgrade and readiness before the system proceeds to the final step: Upgrade old primary (Step 5). This last step typically involves failing over I/O to the newly upgraded Peer (now the active primary) and upgrading the remaining node.

Dell PowerStore Upgrades Participant Guide, Section: "Non-Disruptive Upgrade Operational Steps" (Referenced in training material for exam D-PST-MN-A-24).

Dell PowerStore Maintenance Achievement (D-PST-MN-A-24) Exam Guide, Topic: "Perform PowerStore NDU and maintenance operations."

Dell Technologies, "Dell PowerStore: Clustering and High Availability," White Paper (General reference for Node A/B failover logic during upgrades).