Technical data
Interpreting POST results
POST is a system check that is performed each time the switch is powered on, rebooted, or reset, and
during which the LEDs flash different colors.
Perform the following steps to determine whether POST completed successfully and whether any
errors were detected.
1. Verify that the LEDs on the switch indicate that all components are healthy (LED patterns are
described in LEDs on the port side of the Extension Switch on page 31 and LEDs on the nonport
side of the switch on page 34). If one or more LEDs do not display a healthy state:
a) Verify that the LEDs are not set to "beacon" (this can be determined through the
switchShow command or Web Tools). For information about how to turn beaconing on
and off, refer to the Fabric OS Administrator's Guide or the Web Tools Administrator's
Guide.
b) Follow the recommended action for the observed LED behavior, as shown in LEDs on the
port side of the Extension Switch on page 31 or LEDs on the nonport side of the switch on
page 34.
2. Verify the diagShow command displays that the diagnostic status for all ports in the switch is OK.
3. Review the system log for errors. Errors detected during POST are written to the system log, which
is viewed using the errShow command. For more information about this command, refer to the
Fabric OS Command Reference. For information about specific error messages, refer to the Fabric
OS Message Reference.
Switch maintenance
The switch is designed for high availability and reliability; it does not require any regular physical
maintenance. It includes diagnostic tests and field-replaceable units (FRUs).
Diagnostic tests
In addition to POST, Fabric OS includes diagnostic tests to help you troubleshoot the hardware and
firmware. This includes tests of internal connections and circuitry, fixed media, and the transceivers
and cables in use. The tests are implemented by command, either through a Telnet session or through
a terminal set up for a serial connection to the Extension Switch. Some tests require the ports to be
connected by external cables to allow diagnostics to verify the serializer/deserializer interface,
transceiver, and cable. Some tests require loopback plugs.
Diagnostic tests are run at link speeds of 2-, 4-, 8-, and 16-Gbps. For information about specific
diagnostic tests, refer to the Fabric OS Administrator's Guide.
NOTE
Diagnostic tests may temporarily lock the transmit and receive speed of the links during diagnostic
testing. Brocade recommends that you power-cycle the switch after completing offline diagnostics
tests.
Interpreting POST results
36 Brocade 7840 Extension Switch Hardware Reference Manual
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