IBM Midrange System DS4000 Series Hardware Manual page 485

These entries provided a centralized repository of information about the drivers and
connected hardware. After the changes, the drivers started storing all this information within
the /sys file system. Since Red Hat Enterprise Linux 5 uses Version 2.6.18 of the Linux
kernel, it is affected by this change.
Using the /sys file system means that all the Fibre Channel drivers now use a unified and
consistent manner to report data. However, it also means that the data previously available in
a single file is now scattered across a myriad of files in different parts of the /sys file system.
It is impractical to search through the /sys file system for the relevant files when there is a
large variety of Fibre Channel-related information. Instead of using a manual search, use the
systool command, which provides a simple but powerful means of examining and analyzing
this information. We show several commands in this section that demonstrates what type of
information that the systool command can be used to examine.
For example, to examine information about the Fibre Channel HBAs in a system, use the
command systool -c fc_host -v, which shows:
The WWN of a FC adapter
The FC PortID
The online state
The HBA driver and firmware level
Chapter 7. Advanced maintenance, troubleshooting, and diagnostics
467