Why do I need a "scsi_hostadapter" line in the /etc/modprobe.conf file to load the HBA driver?

The line containing the module scsi_hostadapter in /etc/modprobe.conf informs the kernel which kernel module to load to allow access to the SCSI host adapter. This provides the base level access to SCSI devices attached to the Host Bus Adapter (HBA), additional modules should be automatically loaded depending on the devices attached. Below is a description of how indi...