Complex upgrades that involve both removing old capacity (evacuation) and replacing controllers (hardware NDU) require a "checkpoint" with Pure Storage Support to ensure data safety.
The correct procedure dictates contacting support after removing the fully evacuated drives but before proceeding with the hardware NDU.
Why? Once the old drives are physically removed, the array's configuration state has changed. Support needs to verify that the evacuation was 100% successful, that no stale objects or pointers to the removed drives remain in the database, and that the system is fully healthy and redundant.
Proceeding directly into a controller reboot (NDU) without this verification could lead to issues if the array still "thinks" it needs the removed drives, potentially causing a boot failure or data unavailability during the controller failover.