As promised here comes part two of my “Backup with Bacula and LUKS encrypted USB disks” howto. In part one I explained how to prepare the disks for using them with autofs and how to configure autofs itself. Now we have a good basis for Bacula to use those disks as storage for the backups.
As I said I want to use those disks as virtual tapes in a virtual tape library. This gives us the most flexibility in changing the disks or not (holidays, etc.). With vchanger you get a nice tool to emulate such a virtual tape library. After installation the vchanger binary should be available at /usr/local/bin. I created a config file called vchanger.conf at /usr/local/etc with the following content:

# changer_name  -  [required] Name of this autochanger
changer_name = "usbchanger1"
# state_dir - Directory where virtual drive state and symlinks are created
#             [Default: /var/lib/bacula/]
state_dir = "/var/lib/bacula/usbchanger1"
# logfile  -  Path to a file where errors and debugging info will be logged.
#             [Default: none]
logfile = "/var/lib/bacula/usbchanger1.log"
# slots_per_magazine  -  Number of slots each of the autochanger's magazines
#                        will have. [Default: 10]
slots_per_magazine = 10
# virtual_drives  -  Number of virtual drives to use. [Default: 1]
Virtual_Drives = 1
# magazine  -  [Required] Gives the mountpoint directory of a magazine.
#              Multiple magazine directives may be specified to define
#              a multi-magazine autochanger. Each magazine has the same
#              number of slots, so the autochanger will have
magazine = "/mnt/usbchanger1/magazine"

To use that virtual device with Bacula, modify the configuration of the Bacula storage daemon.

[..]
Autochanger {
 Name = usb-changer-1
 Device = usb-changer-1-drive-0
 Changer Command = "/usr/local/bin/vchanger %c %o %S %a %d"
 Changer Device = "/usr/local/etc/vchanger.conf"
}
#---  drive 0 of the usb-changer-1 autochanger
Device {
 Name = usb-changer-1-drive-0
 DriveIndex = 0
 Autochanger = yes;
 DeviceType = File
 MediaType = File
 ArchiveDevice = /var/lib/bacula/usbchanger1/0/drive0
 RemovableMedia = no;
 RandomAccess = yes;
}
[..]

And add this device as storage to you Bacula director’s configuration.

[..]
Storage {
 Name = usbchanger1   # same as defined by 'baculasd' in vchanger config file
 Address = hostname.of.my.baculasd.system
 SDPort = 9103
 Password = "mysecretpasswort"
 Device = usb-changer-1  # name of the Autochanger resource defined in bacula-sd.conf
 Media Type = File
 Autochanger = yes;
}
[..]

Now we can start initializing the tape library by adding the tapes. For each disk run the following commands after it has been attached to the server.

chown bacula:disk /mnt/usbchanger1/magazine/
vchanger -u bacula -g disk /usr/local/etc/vchanger.conf initmag 1
bconsole << EOF
label barcodes
yes
2
quit
EOF

Now the virtual tape changer is married with Bacula and I am sure they will have a very good time together.

All other things you need to know, e.g. how to to configure Bacula to you needs, what a good backup strategy is, do apply to any other backup media as well. So I am not handling them in this howto. I hope this helped you somehow and feedback is always welcome.