A better way to find out the correct host controller:

# udevadm info -a -p /sys/class/scsi_generic/sg0

where sg0 is the device node of which you’d like to know the corresponding SCSI controller – down that tree you will find hostX mentioned as part of the device path.

And thanks for the rescanning tip, it saved my day.

via Re-scan the SCSI bus in Linux after hot-swapping a drive | Racker Hacker.