So here's the scenario, and I'm hoping @Chopper3 can chime in here. For our SAN fabric, we have a pair of Cisco MDS 9513 FC switches with three EMC frames and four Cisco UCS domains directly attached.
The behavior we are seeing is that the CNA's on the blades are sending FC aborts as a result of the fabric interconnect transmitting FCoE pause frames. Cisco TAC explains this behavior is a result of upstream congestion or latency. We do see a corresponding spike in our data from the 200 or so ESXi servers in the environment reporting latency spikes from 100ms to 2000ms. Some frames and paths seem hit a little harder than the others, which leads me to believe that we're hot-spotting one or more of the links.
The blades are B200M2, B200M3, and B420M3 servers, using. The M2 series use the "Palo" adapter the M81KR, and the M3 series use the VIC1240 adapter.
Since I'm not too depth FC knowledgeable, I'd appreciate some suggestions on how to hunt this down.