Qlogic Storage Networking (Unified Fabric Pilot), Руководство по установке

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5–Validation Methods for DCB and FCoE
Validation Step 5—ETS Verification
51031-00 A 5-25
Exchange Completion Time (Latency Monitor)
Latency is the measurement of how fast commands complete. The time between
command issue and status received is measured in milliseconds (ms).
Figure 5-27 shows the Fibre Channel read-response time in relationship to
changes in traffic load. The graph also shows increases in maximum and average
response times between the switch and the storage, while the switch issues
pause requests to the storage device. The read latency increases from about
10ms to 12.5ms.
Figure 5-27. Read Latency Measurement
In this test, the link congestion did not happen at the host with the
oversubscription scenario. Instead, the switch was congested. This is because of
the multiplexing oversubscription at the egress port. The two ingress links sent a
total of over 100 percent of traffic bandwidth to the egress port, causing the
congestion and generation of PFC pause requests through the FCoE ingress port
to the FCoE target. As
Validation Step 7—Virtualization Verification will show, to
congest the converged network adapter initiator, you can leverage the virtual
machine carrying various applications and unified storage to avoid traffic
multiplexing at the switch.