Background: When the host was performing I/O operations on the LUN, the optical fiber for controller A was removed, and the I/O path switched over to controller B.
After the optical fiber was reinserted, we ran the upTools -S
command, only to find out that no path was generated on controller A. The output is shown in the following figure.
By viewing the information in /var/log/messages, we found out that no physical device was reported, and the system could not generate a physical path. If any device was reported, information similar to the following figure would have been displayed.
Therefore, the I/O path could not be failed back to controller A. Based on the preceding analysis, it is concluded that an HBA driver issue led to a failure to report physical devices.