5 \label{_DVDChapterStart}
6 \index[general]{DVD Volumes}
7 \index[general]{Writing DVDs}
8 \index[general]{DVD Writing}
9 \index[general]{Volumes!DVD}
10 \addcontentsline{toc}{section}{DVD Volumes}
12 Bacula allows you to specify that you want to write to DVD. However,
13 this feature is implemented only in version 1.37 or later.
14 You may in fact write to DVD+RW, DVD+R, DVD-R, or DVD-RW
15 media. The actual process used by Bacula is to first write
16 the image to a spool directory, then when the Volume reaches
17 a certain size or, at your option, at the end of a Job, Bacula
18 will transfer the image from the spool directory to the
19 DVD. The actual work of transferring the image is done
20 by a script {\bf dvd-handler}, and the heart of that
21 script is a program called {\bf growisofs} which allows
22 creating or adding to a DVD ISO filesystem.
24 You must have {\bf dvd+rw-tools} loaded on your system for DVD writing to
25 work. Please note that the original {\bf dvd+rw-tools} package does {\bf
26 NOT} work with Bacula. You must apply a patch which can be found in the
27 {\bf patches} directory of Bacula sources with the name
28 {\bf dvd+rw-tools-5.21.4.10.8.bacula.patch} for version 5.21 of the tools,
29 or patch {bf dvd+rw-tools-6.1.bacula.patch} if you have version 6.1
30 on your system. Unfortunately, this requires you to build the dvd_rw-tools
33 The fact that Bacula cannot use the OS to write directly
34 to the DVD makes the whole process a bit more error prone than
35 writing to a disk or a tape, but nevertheless, it does work if you
36 use some care to set it up properly. However, at the current time
37 (26 August 2006) we still consider this code to be experimental and of
38 BETA quality. As a consequence, please do careful testing before relying
39 on DVD backups in production.
41 The remainder of this chapter explains the various directives that you can
42 use to control the DVD writing.
46 \subsection*{DVD Specific SD Directives}
47 \index[general]{Directives!DVD}
48 \index[general]{DVD Specific SD Directives }
49 \addcontentsline{toc}{subsection}{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 \item [Unmount Command = {\it name-string}]
86 \index[sd]{Unmount Command}
87 Command that must be executed to unmount the device. Before the command is
88 executed, \%a is replaced with the Archive Device, and \%m with the Mount
91 Most frequently, you will define it as follows:
95 Unmount Command = "/bin/umount %m"
99 \item [Write Part Command = {\it name-string}]
100 \index[sd]{Write Part Command }
101 Command that must be executed to write a part to the device. Before the
102 command is executed, \%a is replaced with the Archive Device, \%m with the
103 Mount Point, \%e is replaced with 1 if we are writing the first part,
104 and with 0 otherwise, and \%v with the current part filename.
106 For a DVD, you will most frequently specify the Bacula supplied {\bf
107 dvd-handler} script as follows:
111 Write Part Command = "/path/dvd-handler %a write %e %v"
115 Where {\bf /path} is the path to your scripts install directory, and
116 dvd-handler is the Bacula supplied script file.
117 This command will already be present, but commented out,
118 in the default bacula-sd.conf file. To use it, simply remove
119 the comment (\#) symbol.
122 \item [Free Space Command = {\it name-string}]
123 \index[sd]{Free Space Command }
124 Command that must be executed to check how much free space is left on the
125 device. Before the command is executed,\%a is replaced with the Archive
126 Device, \%m with the Mount Point, \%e is replaced with 1 if we are writing
127 the first part, and with 0 otherwise, and \%v with the current part filename.
129 For a DVD, you will most frequently specify the Bacula supplied {\bf
130 dvd-handler} script as follows:
134 Free Space Command = "/path/dvd-handler %a free"
138 Where {\bf /path} is the path to your scripts install directory, and
139 dvd-freespace is the Bacula supplied script file.
140 If you want to specify your own command, please look at the code in
141 dvd-handler to see what output Bacula expects from this command.
142 This command will already be present, but commented out,
143 in the default bacula-sd.conf file. To use it, simply remove
144 the comment (\#) symbol.
146 If you do not set it, Bacula will expect there is always free space on the
151 In addition to the directives specified above, you must also
152 specify the other standard Device resource directives. Please see the
153 sample DVD Device resource in the default bacula-sd.conf file. Be sure
154 to specify the raw device name for {\bf Archive Device}. It should
155 be a name such as {\bf /dev/cdrom} or {\bf /media/cdrecorder} or
156 {\bf /dev/dvd} depending on your system. It will not be a name such
160 \subsection*{DVD Specific Director Directives}
161 \index[general]{Directives!DVD}
162 \index[general]{DVD Specific Director Directives }
163 \addcontentsline{toc}{subsection}{DVD Specific Director Directives}
165 The following directives are added to the Director's Job resource.
167 \label{WritePartAfterJob}
169 \item [Write Part After Job = \lt{}yes|no\gt{}]
170 \index[dir]{Write Part After Job }
171 If this directive is set to {\bf yes} (default {\bf no}), the
172 Volume written to a temporary spool file for the current Job will
173 be written to the DVD as a new part file
174 will be created after the job is finished.
176 It should be set to {\bf yes} when writing to devices that require a mount
177 (for example DVD), so you are sure that the current part, containing
178 this job's data, is written to the device, and that no data is left in
179 the temporary file on the hard disk. However, on some media, like DVD+R
180 and DVD-R, a lot of space (about 10Mb) is lost everytime a part is
181 written. So, if you run several jobs each after another, you could set
182 this directive to {\bf no} for all jobs, except the last one, to avoid
183 wasting too much space, but to ensure that the data is written to the
184 medium when all jobs are finished.
186 This directive is ignored for devices other than DVDs.
192 \subsection*{Other Points}
193 \index[general]{Points!Other }
194 \index[general]{Other Points }
195 \addcontentsline{toc}{subsection}{Other Points}
198 \item Writing and reading of DVD+RW seems to work quite reliably
199 provided you are using the patched dvd+rw-mediainfo programs.
200 On the other hand, we do not have enough information to ensure
201 that DVD-RW or other forms of DVDs work correctly.
202 \item DVD+RW supports only about 1000 overwrites. Every time you
203 mount the filesystem read/write will count as one write. This can
204 add up quickly, so it is best to mount your DVD+RW filesystem read-only.
205 Bacula does not need the DVD to be mounted read-write, since it uses
206 the raw device for writing.
207 \item Reformatting DVD+RW 10-20 times can apparently make the medium
208 unusable. Normally you should not have to format or reformat
209 DVD+RW media. If it is necessary, current versions of growisofs will
211 \item We have had several problems writing to DVD-RWs (this does NOT
212 concern DVD+RW), because these media have two writing-modes: {\bf
213 Incremental Sequential} and {\bf Restricted Overwrite}. Depending on
214 your device and the media you use, one of these modes may not work
215 correctly (e.g. {\bf Incremental Sequential} does not work with my NEC
216 DVD-writer and Verbatim DVD-RW).
218 To retrieve the current mode of a DVD-RW, run:
220 dvd+rw-mediainfo /dev/xxx
222 where you replace xxx with your DVD device name.
224 {\bf Mounted Media} line should give you the information.
226 To set the device to {\bf Restricted Overwrite} mode, run:
228 dvd+rw-format /dev/xxx
230 If you want to set it back to the default {\bf Incremental Sequential} mode, run:
232 dvd+rw-format -blank /dev/xxx
235 \item Bacula only accepts to write to blank DVDs. To quickly blank a DVD+/-RW, run
238 dd if=/dev/zero bs=1024 count=512 | growisofs -Z /dev/xxx=/dev/fd/0
240 Then, try to mount the device, if it cannot be mounted, it will be considered
241 as blank by Bacula, if it can be mounted, try a full blank (see below).
243 \item If you wish to blank completely a DVD+/-RW, use the following:
245 growisofs -Z /dev/xxx=/dev/zero
247 where you replace xxx with your DVD device name. However, note that this
248 blanks the whole DVD, which takes quite a long time (16 minutes on mine).
249 \item DVD+RW and DVD-RW support only about 1000 overwrites (i.e. don't use the
250 same medium for years if you don't want to have problems...).
252 \item For more informations about DVD writing, please look at the
253 \elink{dvd+rw-tools homepage}{http://fy.chalmers.se/~appro/linux/DVD+RW/}.