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8 – Performing Diagnostics
Running Loopback and Read/Write Buffer Diagnostic Tests
8-6 SN0054651-00 B
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Running the Loopback Test
The loopback test is external to the HBA. If the HBA port is in loop mode, you can
run the loopback test with a loopback connector. If the HBA port is in point-to-point
mode and attached to a switch, an echo test is run instead (no loopback
connector is used). In addition, some driver versions do not require a loopback
connector. See
“Preparing for the Loopback Test” on page 8-3 for information.
The test evaluates the ports (transmit and receive transceivers) on the HBA. More
specifically, the loopback test transmits and receives (loopback) the specified
data, performs a frame cyclic redundancy check (CRC), and looks for disparity
and length errors.
To run a loopback test:
1. Prepare for the test (see “Preparing for Diagnostic Testing” on page 8-2 ).
2. Set the diagnostic test parameters (see Setting the Diagnostic Test
Parameters in the help system).
3. Run the diagnostic test (see Running Diagnostic Tests in the help system).
4. View the diagnostic test results (see Viewing the Diagnostic Test Results in
the help system).
5. Prepare for normal HBA operations (see “Preparing for Normal HBA
Operations” on page 8-4 ).
Running the Read/Write Buffer Test
The read/write buffer test sends specified data through the
SCSI Write Buffer
command to a target device (disk or tape). It then reads the data back through the
SCSI Read Buffer
command and compares the data for errors. The test also
compares the link status of the device before and after the read/write buffer test. If
errors occur, the test indicates a broken or unreliable link between the HBA port
and the device.
NOTE:
The loopback test must be run with the loopback connector (unless the
operating system uses one of the driver versions listed in the
Table 8-1 .
NOTE:
The loopback test is disabled if you are using inbox drivers with SLES 10.0.
NOTE:
Link status is disabled if you are using inbox drivers with SLES 10.0.