First, identify the faulty BBU, either A or B, in Unisphere. Once identified, remove the BBU from the base module by pushing the orange release tab to the right while holding the BBU's handle. Carefully place the removed BBU on a clean, static-free surface to avoid any potential. This section describes how to replace a BBU. If the BBU you want to replace is located on a controller that is running services, ensure that the average CPU usage of each controller does not exceed 40%. During power-on, you need to check the status of the LEDs on the BBU3900. Check. To replace a Battery Backup Unit (BBU) in an EMC VNX5200, VNX5400, VNX5600, or VNX5800, follow these steps. SFP unavailable module alarm clear method. more How to clear Unavailable Optical Module Alarm | SFP Module Alarm | ZTE BBU. This alarm is reported when the link between the BBU and the lower-level RF units malfunctions.