Handrik:
...
> What's sg_map?
>
> I don't seem to have one.
...

$ man sg_map
...
       sg_map - displays mapping between Linux sg and other SCSI devices
...

$ apt-file search sg_map
sg3-utils: /usr/bin/sg_map                
sg3-utils: /usr/bin/sg_map26
sg3-utils: /usr/share/man/man8/sg_map.8.gz
sg3-utils: /usr/share/man/man8/sg_map26.8.gz
votca-csg: /usr/bin/csg_map
votca-csg: /usr/share/man/man1/csg_map.1.gz

To get the serial number of a disk, do

# sg_inq /dev/sda

Regards,
/Karl Hammar