The proc pseudo file system provides some useful information about the SCSI subsystem. The kernel configuration option that selects "proc_fs" is CONFIG_PROC_FS and in almost all cases it should be selected. SCSI specific information is found under the directory /proc/scsi. Probably the most commonly accessed entry is cat /proc/scsi/scsi which lists the attached SCSI devices. See Section 8.3 for more details.
The lower level drivers are allocated proc_fs entries of the form:
The cdrom driver provides information about attached cdrom devices in the /proc/sys/dev/cdrom directory. This will include both SCSI devices (i.e. those controlled by the sr driver) and IDE devices (i.e. those controlled by the ide-cd driver). See Section 9.2.3.
The sg driver provides information about its state and attached hosts and devices in the /proc/scsi/sg directory. See Section 9.4.3.
More general information on the proc pseudo file system can be found in the kernel source file: /usr/src/linux/Documentation/filesystems/proc.txt.