Welcome to LinuxQuestions.
First off read this:
http://www.linuxquestions.org/questi...threadid=71791
Now we need some hardware information like:
What kind of SCSI controller?
What kind of tape drive?
What distribution of linux?
Does the SCSI controller recognize the tape drive during its BIOS scan at boot?
Scan the output of the console command dmesg.
Is the SCSI controller recognized?
Post the output of the console command lsmod. Are any SCSI modules loading?