Background: In the process of host executing the I/O read and write operation for the LUN, plug out the fiber cable from the A controller, switch the I/O path to the B controller.
After plugging in the fiber, view the current path information via the “upTools –S”, we find there isn’t path in the A controller. As the figure 1 displayed:
Figure 1. The path information
Check the logs (/var/log/messages), there isn’t physical information reporting, the system can’t create the physical path. There will be the following information if a device is reported, as the figure 2 displayed.
Figure 2. Logs information
Therefore, the I/O path can’t failback from the B controller to the A controller. According to the above condition, we conclude that it’s the driver’s fault of the HBA card which caused there hasn’t reported the physical device.