[All Linux Operating Systems] A control unit (CU) failover and failback might generate a driver trace log message which is informational only.
A CU failover and failback might generate in the logs a driver trace message that is informational only. When one path fails, the failover path is chosen, and I/O continues on that path until the original path (failback) is restored. The failover and failback process might generate a driver trace message which can be ignored.
Here is an example of how a driver trace message might appear in the logs. Note, in the example, the operating system version is not shown but in the log files, the operating system version is listed.
Mar 28 20:15:14 kernal: INFO: task multipathd:2550 blocked for more than 120 seconds kernal: "echo 0 > /proc/sys/kernal/hung_task_timeout_secs" disables this message. kernal: multipathd d 00000000000 0 2550 1 2551 2533...