5 \label{_DVDChapterStart}
6 \index[general]{DVD Volumes}
7 \index[general]{Writing DVDs}
8 \index[general]{DVD Writing}
9 \index[general]{Volumes!DVD}
11 Bacula allows you to specify that you want to write to DVD. However,
12 this feature is implemented only in version 1.37 or later.
13 You may in fact write to DVD+RW, DVD+R, DVD-R, or DVD-RW
14 media. The actual process used by Bacula is to first write
15 the image to a spool directory, then when the Volume reaches
16 a certain size or, at your option, at the end of a Job, Bacula
17 will transfer the image from the spool directory to the
18 DVD. The actual work of transferring the image is done
19 by a script {\bf dvd-handler}, and the heart of that
20 script is a program called {\bf growisofs} which allows
21 creating or adding to a DVD ISO filesystem.
23 You must have {\bf dvd+rw-tools} loaded on your system for DVD writing to
24 work. Please note that the original {\bf dvd+rw-tools} package does {\bf
25 NOT} work with Bacula. You must apply a patch which can be found in the
26 {\bf patches} directory of Bacula sources with the name
27 {\bf dvd+rw-tools-5.21.4.10.8.bacula.patch} for version 5.21 of the tools,
28 or patch {bf dvd+rw-tools-6.1.bacula.patch} if you have version 6.1
29 on your system. Unfortunately, this requires you to build the dvd\_rw-tools
32 Note, some Linux distros such as Debian dvd+rw-tools-7.0-4 package already
33 have the patch applied, so please check.
35 The fact that Bacula cannot use the OS to write directly
36 to the DVD makes the whole process a bit more error prone than
37 writing to a disk or a tape, but nevertheless, it does work if you
38 use some care to set it up properly. However, at the current time
39 (version 1.39.30 -- 12 December 2006) we still consider this code to be
40 BETA quality. As a consequence, please do careful testing before relying
41 on DVD backups in production.
43 The remainder of this chapter explains the various directives that you can
44 use to control the DVD writing.
47 \section{DVD Specific SD Directives}
48 \index[general]{Directives!DVD}
49 \index[general]{DVD Specific SD Directives }
51 The following directives are added to the Storage daemon's
56 \item [Requires Mount = {\it Yes|No}]
57 \index[sd]{Requires Mount }
58 You must set this directive to {\bf yes} for DVD-writers, and to {\bf no} for
59 all other devices (tapes/files). This directive indicates if the device
60 requires to be mounted using the {\bf Mount Command}.
61 To be able to write a DVD, the following directives must also be
62 defined: {\bf Mount Point}, {\bf Mount Command}, {\bf Unmount Command} and
63 {\bf Write Part Command}.
65 \item [Mount Point = {\it directory}]
66 \index[sd]{Mount Point}
67 Directory where the device can be mounted.
69 \item [Mount Command = {\it name-string}]
70 \index[sd]{Mount Command}
71 Command that must be executed to mount the device. Although the
72 device is written directly, the mount command is necessary in
73 order to determine the free space left on the DVD. Before the command is
74 executed, \%a is replaced with the Archive Device, and \%m with the Mount
77 Most frequently, you will define it as follows:
81 Mount Command = "/bin/mount -t iso9660 -o ro %a %m"
85 However, if you have defined a mount point in /etc/fstab, you might be
86 able to use a mount command such as:
90 Mount Command = "/bin/mount /media/dvd"
95 \item [Unmount Command = {\it name-string}]
96 \index[sd]{Unmount Command}
97 Command that must be executed to unmount the device. Before the command is
98 executed, \%a is replaced with the Archive Device, and \%m with the Mount
101 Most frequently, you will define it as follows:
105 Unmount Command = "/bin/umount %m"
109 \item [Write Part Command = {\it name-string}]
110 \index[sd]{Write Part Command }
111 Command that must be executed to write a part to the device. Before the
112 command is executed, \%a is replaced with the Archive Device, \%m with the
113 Mount Point, \%e is replaced with 1 if we are writing the first part,
114 and with 0 otherwise, and \%v with the current part filename.
116 For a DVD, you will most frequently specify the Bacula supplied {\bf
117 dvd-handler} script as follows:
121 Write Part Command = "/path/dvd-handler %a write %e %v"
125 Where {\bf /path} is the path to your scripts install directory, and
126 dvd-handler is the Bacula supplied script file.
127 This command will already be present, but commented out,
128 in the default bacula-sd.conf file. To use it, simply remove
129 the comment (\#) symbol.
132 \item [Free Space Command = {\it name-string}]
133 \index[sd]{Free Space Command }
134 Command that must be executed to check how much free space is left on the
135 device. Before the command is executed,\%a is replaced with the Archive
138 For a DVD, you will most frequently specify the Bacula supplied {\bf
139 dvd-handler} script as follows:
143 Free Space Command = "/path/dvd-handler %a free"
147 Where {\bf /path} is the path to your scripts install directory, and
148 dvd-freespace is the Bacula supplied script file.
149 If you want to specify your own command, please look at the code in
150 dvd-handler to see what output Bacula expects from this command.
151 This command will already be present, but commented out,
152 in the default bacula-sd.conf file. To use it, simply remove
153 the comment (\#) symbol.
155 If you do not set it, Bacula will expect there is always free space on the
160 In addition to the directives specified above, you must also
161 specify the other standard Device resource directives. Please see the
162 sample DVD Device resource in the default bacula-sd.conf file. Be sure
163 to specify the raw device name for {\bf Archive Device}. It should
164 be a name such as {\bf /dev/cdrom} or {\bf /media/cdrecorder} or
165 {\bf /dev/dvd} depending on your system. It will not be a name such
168 Finally, for {\bf growisofs} to work, it must be able to lock
169 a certain amount of memory in RAM. If you have restrictions on
170 this function, you may have failures. Under {\bf bash}, you can
171 set this with the following command:
179 \section{Edit Codes for DVD Directives}
180 \index[general]{Directives!DVD Edit Codes}
181 \index[general]{Edit Codes for DVD Directives }
183 Before submitting the {\bf Mount Command}, {\bf Unmount Command},
184 {\bf Write Part Command}, or {\bf Free Space Command} directives
185 to the operating system, Bacula performs character substitution of the
186 following characters:
191 %a = Archive device name
192 %e = erase (set if cannot mount and first part)
195 %v = last part name (i.e. filename)
201 \section{DVD Specific Director Directives}
202 \index[general]{Directives!DVD}
203 \index[general]{DVD Specific Director Directives }
205 The following directives are added to the Director's Job resource.
207 \label{WritePartAfterJob}
209 \item [Write Part After Job = \lt{}yes|no\gt{}]
210 \index[dir]{Write Part After Job }
211 If this directive is set to {\bf yes} (default {\bf no}), the
212 Volume written to a temporary spool file for the current Job will
213 be written to the DVD as a new part file
214 will be created after the job is finished.
216 It should be set to {\bf yes} when writing to devices that require a mount
217 (for example DVD), so you are sure that the current part, containing
218 this job's data, is written to the device, and that no data is left in
219 the temporary file on the hard disk. However, on some media, like DVD+R
220 and DVD-R, a lot of space (about 10Mb) is lost everytime a part is
221 written. So, if you run several jobs each after another, you could set
222 this directive to {\bf no} for all jobs, except the last one, to avoid
223 wasting too much space, but to ensure that the data is written to the
224 medium when all jobs are finished.
226 This directive is ignored for devices other than DVDs.
232 \section{Other Points}
233 \index[general]{Points!Other }
234 \index[general]{Other Points }
237 \item Please be sure that you have any automatic DVD mounting
238 disabled before running Bacula -- this includes auto mounting
239 in /etc/fstab, hotplug, ... If the DVD is automatically
240 mounted by the OS, it will cause problems when Bacula tries
241 to mount/unmount the DVD.
242 \item Please be sure that you the directive {\bf Write Part After Job}
243 set to {\bf yes}, otherwise the last part of the data to be
244 written will be left in the DVD spool file and not written to
245 the DVD. The DVD will then be unreadable until this last part
246 is written. If you have a series of jobs that are run one at
247 a time, you can turn this off until the last job is run.
248 \item The current code is not designed to have multiple simultaneous
249 jobs writing to the DVD. As a consequence, please ensure that
250 only one DVD backup job runs at any time.
251 \item Writing and reading of DVD+RW seems to work quite reliably
252 provided you are using the patched dvd+rw-mediainfo programs.
253 On the other hand, we do not have enough information to ensure
254 that DVD-RW or other forms of DVDs work correctly.
255 \item DVD+RW supports only about 1000 overwrites. Every time you
256 mount the filesystem read/write will count as one write. This can
257 add up quickly, so it is best to mount your DVD+RW filesystem read-only.
258 Bacula does not need the DVD to be mounted read-write, since it uses
259 the raw device for writing.
260 \item Reformatting DVD+RW 10-20 times can apparently make the medium
261 unusable. Normally you should not have to format or reformat
262 DVD+RW media. If it is necessary, current versions of growisofs will
264 \item We have had several problems writing to DVD-RWs (this does NOT
265 concern DVD+RW), because these media have two writing-modes: {\bf
266 Incremental Sequential} and {\bf Restricted Overwrite}. Depending on
267 your device and the media you use, one of these modes may not work
268 correctly (e.g. {\bf Incremental Sequential} does not work with my NEC
269 DVD-writer and Verbatim DVD-RW).
271 To retrieve the current mode of a DVD-RW, run:
273 dvd+rw-mediainfo /dev/xxx
275 where you replace xxx with your DVD device name.
277 {\bf Mounted Media} line should give you the information.
279 To set the device to {\bf Restricted Overwrite} mode, run:
281 dvd+rw-format /dev/xxx
283 If you want to set it back to the default {\bf Incremental Sequential} mode, run:
285 dvd+rw-format -blank /dev/xxx
288 \item Bacula only accepts to write to blank DVDs. To quickly blank a DVD+/-RW, run
291 dd if=/dev/zero bs=1024 count=512 | growisofs -Z /dev/xxx=/dev/fd/0
293 Then, try to mount the device, if it cannot be mounted, it will be considered
294 as blank by Bacula, if it can be mounted, try a full blank (see below).
296 \item If you wish to blank completely a DVD+/-RW, use the following:
298 growisofs -Z /dev/xxx=/dev/zero
300 where you replace xxx with your DVD device name. However, note that this
301 blanks the whole DVD, which takes quite a long time (16 minutes on mine).
302 \item DVD+RW and DVD-RW support only about 1000 overwrites (i.e. don't use the
303 same medium for years if you don't want to have problems...).
305 To write to the DVD the first time use:
307 growisofs -Z /dev/xxx filename
310 To add additional files (more parts use):
313 growisofs -M /dev/xxx filename
316 The option {\bf -use-the-force-luke=4gms} was added in growisofs 5.20 to
317 override growisofs' behavior of always checking for the 4GB limit.
318 Normally, this option is recommended for all Linux 2.6.8 kernels or
319 greater, since these newer kernels can handle writing more than 4GB.
320 See below for more details on this subject.
322 \item For more information about DVD writing, please look at the
323 \elink{dvd+rw-tools homepage}{http://fy.chalmers.se/~appro/linux/DVD+RW/}.
325 \item According to bug #912, bscan cannot read multi-volume DVDs. This is
326 on our TODO list, but unless someone submits a patch it is not likely to be
327 done any time in the near future. (9 Sept 2007).