An initrd image is needed for loading your SCSI module at boot time. If you do not need an initrd image, do not make one and do not edit lilo.conf or grub.conf to include this image.
The /sbin/mkinitrd shell script can build a proper initrd image for your machine if the following conditions are met:
1) The loopback block device is available.
2) The /etc/modules.conf file has a line for your SCSI adapter; for example:
alias scsi_hostadapter BusLogic
To build the new initrd image, run /sbin/mkinitrd with parameters such as this:
/sbin/mkinitrd /boot/initrd-2.4.7-3.img 2.4.7-3
In the above example, /boot/initrd-2.4.7-3.img is the filename of the new initrd image. 2.4.7-3 is the kernel whose modules (from /lib/modules) should be used in the initrd image. This is not necessarily the same as the version number of the currently running kernel.
If you don't find above info suitable for you, try this