Checking system hardware
Check the power supplies and LED displays to see if any error codes are displayed. Run the AIX® diag command to test the system unit.
Without an argument, diag runs as a menu-driven program. You can also run diag on a specific piece of hardware. For example:
diag -d hdisk0 -c
Starting diagnostics.
Ending diagnostics.This output indicates that hdisk0 is okay.