Figure 2-2 Post Diagnostic Running Across Frus - Sun Microsystems Sun Fire V440 Diagnostics And Troubleshooting Manual

Identifying FRUs
An important feature of POST error messages is the H/W under test line. (The
second line in
The H/W under test line indicates which FRU or FRUs may be responsible for the
error. Note that in
TABLE 2-15
likely caused by bad integrated circuits (IO-Bridge) or electrical pathways on the
motherboard. However, the error message also indicates that the master CPU, in this
case CPU 1, may be at fault. For information on how Sun Fire V440 CPUs are
numbered, see "Identifying CPU/Memory Modules" on page 46.
Though beyond the scope of this manual, it is worth noting that POST error
messages provide fault isolation capability beyond the FRU level. In the current
example, the MSG line located immediately below the H/W under test line specifies
the particular integrated circuit (DEVICE NAME: SCSI) most likely at fault. This
level of isolation is most useful at the repair depot.
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 V440 server, shown in
CPU
CPU/memory
module
FIGURE 2-2
The dashed line in
diagnostic is running in the CPU in the left part of the diagram. This diagnostic
attempts to access registers in a PCI device located in the right side of the diagram.
If this access fails, there could be a fault in the PCI device, or, less likely, in one of the
data paths or components leading to that PCI device. The POST diagnostic can tell
you only that the test failed, but not why. So, though the POST diagnostic may
present very precise data about the nature of the test failure, potentially several
different FRUs could be implicated.
12 Sun Fire V440 Server Diagnostics and Troubleshooting Guide • July 2003
CODE EXAMPLE 2-1
CODE EXAMPLE 2-1
to decode some of the terms, you can see that this POST error was most
I/O
bridge
Motherboard
POST Diagnostic Running Across FRUs
represents a boundary between FRUs. Suppose a POST
FIGURE 2-2
.)
, two different FRUs are indicated. Using
FIGURE 2-2
PCI
device
.