The "Failed to RUN_ARRAY /dev/md0 invalid argument" error can occur when you try to start a Linux software RAID array and the array cannot be started due to an invalid argument or configuration.
There are a few possible causes of this error:
The RAID array configuration is incorrect or corrupt. This can happen if the configuration file (usually /etc/mdadm.conf) or the metadata stored on the RAID devices is incorrect or has been damaged. You can try rebuilding the array configuration by running the mdadm --examine --scan command and using the output to create a new configuration file. You can then use the mdadm --assemble --scan command to try to start the array.
The RAID devices are not available or have failed. This can happen if one or more of the devices in the array have become unavailable or have failed. You can check the status of the devices using the mdadm --detail /dev/md0 command and looking for any errors or failed devices. You can also try running the smartctl command to check the status of the individual devices.
The RAID devices are not properly partitioned or formatted. This can happen if the devices have not been properly partitioned or formatted for use in a RAID array. You can check the partition table and filesystem on the devices using the fdisk -l and lsblk commands, respectively.
The kernel module for the RAID array is not loaded. This can happen if the kernel module for the RAID array (usually md-mod) is not loaded or has not been compiled into the kernel. You can check if the module is loaded using the lsmod command and try loading it manually using the modprobe command.
If you continue to have issues with the RAID array, you may want to check the system logs for more information about the cause of the error. You may also want to consider consulting the documentation for the mdadm tool or seeking additional help from a qualified system administrator or support representative.