Sun Microsystems Sun Fire V480, Руководство администратора

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88 Sun Fire V480 Server Administration Guide • February 2002
Why a POST Error May Implicate Multiple FRUs
Because each test operates at such a low level, the POST diagnostics are often more
definite in reporting the minute details of the error, like the numerical values of
expected and observed results, than they are about reporting which FRU is
responsible. If this seems counter-intuitive, consider the block diagram of one data
path within a Sun Fire V480 server, shown in
FIGURE 6-3
.
FIGURE 6-3
POST Diagnostic Running Across FRUs
The dashed lines in
FIGURE 6-3
represent boundaries between FRUs. Suppose a POST
diagnostic is running in the CPU in the left part of the diagram. This diagnostic
attempts to initiate a built-in self-test in a PCI device located in the right side of the
diagram.
If this built-in self-test fails, there could be a fault in the PCI controller, or, less likely,
in one of the data paths or components leading to that PCI controller. The POST
diagnostic can tell you only that the test failed, but not
why . So, though the POST
may present very precise data about the nature of the test failure, any of three
different FRUs could be implicated.
Controlling POST Diagnostics
You control POST diagnostics (and other aspects of the boot process) by setting
OpenBoot configuration variables in the IDPROM. Changes to OpenBoot
configuration variables generally take effect only after the machine is restarted.
CPU
I/O
bridge
Data
switch
PCI
controller
5-way
CPU / Memory board Centerplane PCI riser board
data
switch