An Implementation Engineer is performing a FlashArray//XR4 to FlashArray//XL upgrade, and is preparing to remove...

During a complex cross-generational Hardware Non-Disruptive Upgrade (HWNDU) from a FlashArray//XR4 to a FlashArray//XL, the Implementation Engineer must carefully orchestrate the shutdown and removal of the legacy compute nodes. Before physically unlatching and removing the CT0 controller, the Purity//FA operating system processes running on that specific node must be gracefully halted.

Because standard user commands do not allow for this level of low-level service manipulation, the engineer must utilize the purewes (Wessex) command-line suite. Wessex is the internal engineering toolkit used to override high-availability states during hardware replacements.

The correct command to execute is purewes controller disable --purity --verify-mode secondary --verify-array < ARRAY_NAME > ct0 .

This command contains several critical safety mechanisms. The --purity flag specifies that the script should shut down the Purity storage processes rather than just network interfaces. The --verify-mode secondary flag is a mandatory safeguard; it checks the cluster state to guarantee that CT0 has already successfully failed over its active host I/O responsibilities to CT1. If CT0 is still the primary controller, the command will intentionally fail to prevent an accidental storage outage. Finally, --verify-array ensures the engineer is executing this disruptive command on the correct physical array, which is crucial when multiple SSH sessions are open in a busy datacenter.