Which of the Following Statements About the Performance Optimization Check

Which of the following statements about the performance optimization check items of the N8500 clustered NAS storage systems are correct? (Select three)

A) Check whether the BBUs are faulty. If only one BBU is faulty, the current write policy of LUNs changes to write through.
B) Log in to the ISM and check whether alarms indicating slow disk response exist.
C) Check on the ISM whether bit errors exist on Fibre Channel ports.
D) Check whether front-end service ports are functioning at the optimal rate. For example, check whether the port rate is 4 Gbit/s when the bandwidth is 8 Gbit/s.