HP HPE Alletra 2140 Hardware Manual page 115

ctrlr --list --array array_name
c) Halt the standby controller.
halt --array array_name --controller {A | B}
Example
$ halt --array array123 --controller A
2. Remove the existing Standby controller to be upgraded.
a) Disconnect the power cords from the two controller power supplies.
b) Label all cables to ensure proper recabling later, then remove them from the controller.
c) Loosen the left and right thumbscrews to free the controller release levers from the controller.
1 Thumbscrew
2 Controller release lever
d) Pull the controller release levers down until they stop. The controller ejects slightly from the chassis.
e) Supporting the weight of the controller, pull the controller release levers to slide the controller out of the chassis. Then
place the controller on a flat surface.
1 Controller release lever (open)
2 Controller
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3 Controller
3 Chassis
Upgrade Procedures 115