A UCS B-Series blade server shows high CPU latency when processing network I/O. The engineer suspects a bottleneck in the I/O subsystem. Which metric in UCS Manager should be examined first?
Errors cause retransmissions and latency
Why this answer
Fabric port error counts directly reflect physical-layer issues (e.g., CRC errors, alignment errors, link flaps) that cause retransmissions and backpressure, leading to high CPU latency on the blade server. In UCS Manager, these counters are the first place to check when suspecting an I/O subsystem bottleneck because they pinpoint problems in the fabric interconnect or cabling before examining higher-layer metrics.
Exam trap
Cisco often tests the distinction between utilization metrics (which show load) and error metrics (which show health), so candidates mistakenly pick vNIC utilization thinking high usage equals a bottleneck, when the real issue is physical-layer errors causing retransmissions.
How to eliminate wrong answers
Option A is wrong because vNIC utilization percentage measures throughput usage, not errors or latency; high utilization alone does not cause CPU latency unless accompanied by errors or congestion. Option C is wrong because memory usage statistics indicate system memory pressure, which can affect overall performance but is not specific to the I/O subsystem or network latency. Option D is wrong because power consumption per server relates to thermal or power capacity issues, not to network I/O latency or fabric errors.