$ dpkg -l wodim | tail -1
ii  wodim          9:1.1.6-1      command line CD/DVD writing tool

$ mount | grep media
/dev/hdd on /media/cdrom1 type iso9660 (ro,noexec,nosuid,nodev,user=username)
/dev/hdb on /media/cdrom0 type iso9660 (ro,noexec,nosuid,nodev,user=username)


$ /usr/bin/wodim -scanbus
/usr/bin/wodim: No such file or directory.
Cannot open SCSI driver!
For possible targets try 'wodim --devices' or 'wodim -scanbus'.
For possible transport specifiers try 'wodim dev=help'.
For IDE/ATAPI devices configuration, see the file README.ATAPI.setup from
the wodim documentation.

$ ls -l /usr/bin/wodim
-rwxr-xr-x 1 root root 350816 2007-05-06 11:36 /usr/bin/wodim

$ /usr/bin/wodim -scanbus dev=/dev/hdb   # note /hdb
Error trying to open /dev/hdb exclusively (Device or resource busy)... retrying in 1 second.
Error trying to open /dev/hdb exclusively (Device or resource busy)... retrying in 1 second.
Error trying to open /dev/hdb exclusively (Device or resource busy)... retrying in 1 second.

$ /usr/bin/wodim -scanbus dev=/dev/hdd     # note /hdd
Error trying to open /dev/hdd exclusively (Device or resource busy)... retrying in 1 second.
Error trying to open /dev/hdd exclusively (Device or resource busy)... retrying in 1 second.
Error trying to open /dev/hdd exclusively (Device or resource busy)... retrying in 1 second.


####  NOTE (below)  This is an OLD testing version of Wodim,    ####
####  i built and installed a while ago.(note /usr/local/ path) ####


$ /usr/local/bin/wodim -scanbus dev=ATAPI
This is wodim, not cdrecord. Don't expect it to behave like cdrecord in any
way, don't refer to it as "cdrecord". Send problem reports to
debburn-devel@lists.alioth.debian.org, don't bother Joerg Schilling with any
problems caused by this application.
Copyright (C) 2006 cdrkit maintainers, (C) 1994-2006 Joerg Schilling

Using libscg version 'debburn project-0.8ubuntu1+debburn1'.
/usr/local/bin/wodim: Warning: using inofficial version of libscg (debburn project-0.8ubuntu1+debburn1 '@(#)scsitransp.c       1.91 04/06/17 Copyright 1988,1995,2000-2004 J. Schilling').
/usr/local/bin/wodim: Warning: using inofficial libscg transport code version (cdrkit-team-scsi-linux-ata.c-1.7 '@(#)scsi-linux-ata.c  1.7 04/06/12 Copyright 2002 J. Schilling').
scsibus0:
        0,0,0     0) *
        0,1,0     1) 'LITE-ON ' 'LTR-32123S      ' 'XS0R' Removable CD-ROM
        0,2,0     2) *
        0,3,0     3) *
        0,4,0     4) *
        0,5,0     5) *
        0,6,0     6) *
        0,7,0     7) *
scsibus1:
        1,0,0   100) *
        1,1,0   101) '_NEC    ' 'DVD_RW ND-3550A ' '1.05' Removable CD-ROM
        1,2,0   102) *
        1,3,0   103) *
        1,4,0   104) *
        1,5,0   105) *
        1,6,0   106) *
        1,7,0   107) *


### and still both optical drives are loop mounted ###

$ mount | grep media
/dev/hdd on /media/cdrom1 type iso9660 (ro,noexec,nosuid,nodev,user=username)
/dev/hdb on /media/cdrom0 type iso9660 (ro,noexec,nosuid,nodev,user=username)


#######       Stopped using OLD Version here      #####





### NOW, i umount only one of the drives /dev/hdb mounted on /media/cdrom0 ###

$ umount /media/cdrom0

### Only /dev/hdd remains on /media/cdrom1 ###

$ mount | grep media
/dev/hdd on /media/cdrom1 type iso9660 (ro,noexec,nosuid,nodev,user=stompthebozo)


### I run same commands as above - it now finds the one i umounted (/dev/hdb) ###

$ /usr/bin/wodim -scanbus
scsibus1000:
        1000,0,0 100000) *
        1000,1,0 100001) 'LITE-ON ' 'LTR-32123S      ' 'XS0R' Removable CD-ROM
        1000,2,0 100002) *
        1000,3,0 100003) *
        1000,4,0 100004) *
        1000,5,0 100005) *
        1000,6,0 100006) *
        1000,7,0 100007) *