4 \chapter{Autochanger Support}
5 \label{AutochangersChapter}
6 \index[general]{Support!Autochanger }
7 \index[general]{Autochanger Support }
9 Bacula provides autochanger support for reading and writing tapes. In
10 order to work with an autochanger, Bacula requires a number of things, each of
11 which is explained in more detail after this list:
14 \item A script that actually controls the autochanger according to commands
15 sent by Bacula. We furnish such a script that works with {\bf mtx} found in
16 the {\bf depkgs} distribution.
18 \item That each Volume (tape) to be used must be defined in the Catalog and
19 have a Slot number assigned to it so that Bacula knows where the Volume is in
20 the autochanger. This is generally done with the {\bf label} command,
21 but can also done after the tape is labeled using the {\bf update slots}
23 below for more details. You must pre-label the tapes manually before
26 \item Modifications to your Storage daemon's Device configuration resource to
27 identify that the device is a changer, as well as a few other parameters.
29 \item You should also modify your Storage resource definition in the
30 Director's configuration file so that you are automatically prompted for the
31 Slot when labeling a Volume.
33 \item You need to ensure that your Storage daemon (if not running as root)
34 has access permissions to both the tape drive and the control device.
36 \item You need to have {\bf Autochanger = yes} in your Storage resource
37 in your bacula-dir.conf file so that you will be prompted for the
38 slot number when you label Volumes.
41 In version 1.37 and later, there is a new \ilink{Autochanger
42 resource}{AutochangerRes} that permits you to group Device resources thus
43 creating a multi-drive autochanger. If you have an autochanger,
44 you {\bf must} use this new resource.
46 Bacula uses its own {\bf mtx-changer} script to interface with a program
47 that actually does the tape changing. Thus in principle, {\bf mtx-changer}
48 can be adapted to function with any autochanger program, or you can
49 call any other script or program. The current
50 version of {\bf mtx-changer} works with the {\bf mtx} program. However,
51 FreeBSD users have provided a script in the {\bf examples/autochangers}
52 directory that allows Bacula to use the {\bf chio} program.
54 Bacula also supports autochangers with barcode
55 readers. This support includes two Console commands: {\bf label barcodes}
56 and {\bf update slots}. For more details on these commands, see the "Barcode
57 Support" section below.
59 Current Bacula autochanger support does not include cleaning, stackers, or
60 silos. Stackers and silos are not supported because Bacula expects to
61 be able to access the Slots randomly.
62 However, if you are very careful to setup Bacula to access the Volumes
63 in the autochanger sequentially, you may be able to make Bacula
64 work with stackers (gravity feed and such).
66 Support for multi-drive
67 autochangers requires the \ilink{Autochanger resource}{AutochangerRes}
68 introduced in version 1.37. This resource is also recommended for single
71 In principle, if {\bf mtx} will operate your changer correctly, then it is
72 just a question of adapting the {\bf mtx-changer} script (or selecting one
73 already adapted) for proper interfacing. You can find a list of autochangers
74 supported by {\bf mtx} at the following link:
75 \elink{http://mtx.opensource-sw.net/compatibility.php}
76 {http://mtx.opensource-sw.net/compatibility.php}.
77 The home page for the {\bf mtx} project can be found at:
78 \elink{http://mtx.opensource-sw.net/}{http://mtx.opensource-sw.net/}.
80 Note, we have feedback from some users that there are certain
81 incompatibilities between the Linux kernel and mtx. For example between
82 kernel 2.6.18-8.1.8.el5 of CentOS and RedHat and version 1.3.10 and 1.3.11
83 of mtx. This was fixed by upgrading to a version 2.6.22 kernel.
85 In addition, apparently certain versions of mtx, for example, version
86 1.3.11 limit the number of slots to a maximum of 64. The solution was to
89 If you are having troubles, please use the {\bf auto} command in the {\bf
90 btape} program to test the functioning of your autochanger with Bacula. When
91 Bacula is running, please remember that for many distributions (e.g. FreeBSD,
92 Debian, ...) the Storage daemon runs as {\bf bacula.tape} rather than {\bf
93 root.root}, so you will need to ensure that the Storage daemon has sufficient
94 permissions to access the autochanger.
96 Some users have reported that the the Storage daemon blocks under certain
97 circumstances in trying to mount a volume on a drive that has a different
98 volume loaded. As best we can determine, this is simply a matter of
99 waiting a bit. The drive was previously in use writing a Volume, and
100 sometimes the drive will remain BLOCKED for a good deal of time (up to 7
101 minutes on a slow drive) waiting for the cassette to rewind and to unload
102 before the drive can be used with a different Volume.
105 \section{Knowing What SCSI Devices You Have}
106 \index[general]{Have!Knowing What SCSI Devices You }
107 \index[general]{Knowing What SCSI Devices You Have }
108 \index[general]{SCSI devices}
109 \index[general]{devices!SCSI}
119 to see what SCSI devices you have available. You can also:
123 cat /proc/scsi/sg/device_hdr /proc/scsi/sg/devices
127 to find out how to specify their control address ({\bf /dev/sg0} for the
128 first, {\bf /dev/sg1} for the second, ...) on the {\bf Changer Device = }
131 For more detailed information on what SCSI devices you have please see
132 the \ilink{Linux SCSI Tricks}{SCSITricks} section of the Tape Testing
133 chapter of this manual.
135 Under FreeBSD, you can use:
143 To list the SCSI devices as well as the {\bf /dev/passn} that you will use on
144 the Bacula {\bf Changer Device = } directive.
146 Please check that your Storage daemon has permission to access this
149 The following tip for FreeBSD users comes from Danny Butroyd:
150 on reboot Bacula will NOT have permission to
151 control the device /dev/pass0 (assuming this is your changer device).
152 To get around this just edit the /etc/devfs.conf file and add the
153 following to the bottom:
156 own pass0 root:bacula
158 own nsa0.0 root:bacula
163 This gives the bacula group permission to write to the nsa0.0 device
164 too just to be on the safe side. To bring these changes into effect
167 /etc/rc.d/devfs restart
169 Basically this will stop you having to manually change permissions on these
170 devices to make Bacula work when operating the AutoChanger after a reboot.
173 \section{Example Scripts}
174 \index[general]{Scripts!Example }
175 \index[general]{Example Scripts }
177 Please read the sections below so that you understand how autochangers work
178 with Bacula. Although we supply a default {\bf mtx-changer} script, your
179 autochanger may require some additional changes. If you want to see examples
180 of configuration files and scripts, please look in the {\bf
181 \lt{}bacula-src\gt{}/examples/devices} directory where you will find an
182 example {\bf HP-autoloader.conf} Bacula Device resource, and several {\bf
183 mtx-changer} scripts that have been modified to work with different
189 \index[general]{Slots }
191 To properly address autochangers, Bacula must know which Volume is in each
192 {\bf slot} of the autochanger. Slots are where the changer cartridges reside
193 when not loaded into the drive. Bacula numbers these slots from one to the
194 number of cartridges contained in the autochanger.
196 Bacula will not automatically use a Volume in your autochanger unless it is
197 labeled and the slot number is stored in the catalog and the Volume is marked
198 as InChanger. This is because it must know where each volume is (slot) to
199 be able to load the volume.
200 For each Volume in your
201 changer, you will, using the Console program, assign a slot. This information
202 is kept in {\bf Bacula's} catalog database along with the other data for the
203 volume. If no slot is given, or the slot is set to zero, Bacula will not
204 attempt to use the autochanger even if all the necessary configuration records
205 are present. When doing a {\bf mount} command on an autochanger, you must
206 specify which slot you want mounted. If the drive is loaded with a tape
207 from another slot, it will unload it and load the correct tape, but
208 normally, no tape will be loaded because an {\bf unmount} command causes
209 Bacula to unload the tape in the drive.
212 You can check if the Slot number and InChanger flag are set by doing a:
217 in the Console program.
220 \section{Multiple Devices}
221 \index[general]{Devices!Multiple}
222 \index[general]{Multiple Devices}
224 Some autochangers have more than one read/write device (drive). The
225 new \ilink{Autochanger resource}{AutochangerRes} introduced in version
226 1.37 permits you to group Device resources, where each device
227 represents a drive. The Director may still reference the Devices (drives)
228 directly, but doing so, bypasses the proper functioning of the
229 drives together. Instead, the Director (in the Storage resource)
230 should reference the Autochanger resource name. Doing so permits
231 the Storage daemon to ensure that only one drive uses the mtx-changer
232 script at a time, and also that two drives don't reference the
235 Multi-drive requires the use of the {\bf
236 Drive Index} directive in the Device resource of the Storage daemon's
237 configuration file. Drive numbers or the Device Index are numbered beginning
238 at zero, which is the default. To use the second Drive in an autochanger, you
239 need to define a second Device resource and set the Drive Index to 1 for
240 that device. In general, the second device will have the same {\bf Changer
241 Device} (control channel) as the first drive, but a different {\bf Archive
244 As a default, Bacula jobs will prefer to write to a Volume that is
245 already mounted. If you have a multiple drive autochanger and you want
246 Bacula to write to more than one Volume in the same Pool at the same
247 time, you will need to set \ilink{Prefer Mounted Volumes} {PreferMountedVolumes}
248 in the Directors Job resource to {\bf no}. This will cause
249 the Storage daemon to maximize the use of drives.
252 \label{ConfigRecords}
253 \section{Device Configuration Records}
254 \index[general]{Records!Device Configuration }
255 \index[general]{Device Configuration Records }
257 Configuration of autochangers within Bacula is done in the Device resource of
258 the Storage daemon. Four records: {\bf Autochanger}, {\bf Changer Device},
259 {\bf Changer Command}, and {\bf Maximum Changer Wait} control how Bacula uses
262 These four records, permitted in {\bf Device} resources, are described in
263 detail below. Note, however, that the {\bf Changer Device} and the
264 {\bf Changer Command} directives are not needed in the Device resource
265 if they are present in the {\bf Autochanger} resource.
269 \item [Autochanger = {\it Yes|No} ]
270 \index[sd]{Autochanger }
271 The {\bf Autochanger} record specifies that the current device is or is not
272 an autochanger. The default is {\bf no}.
274 \item [Changer Device = \lt{}device-name\gt{}]
275 \index[sd]{Changer Device }
276 In addition to the Archive Device name, you must specify a {\bf Changer
277 Device} name. This is because most autochangers are controlled through a
278 different device than is used for reading and writing the cartridges. For
279 example, on Linux, one normally uses the generic SCSI interface for
280 controlling the autochanger, but the standard SCSI interface for reading and
281 writing the tapes. On Linux, for the {\bf Archive Device = /dev/nst0}, you
282 would typically have {\bf Changer Device = /dev/sg0}. Note, some of the more
283 advanced autochangers will locate the changer device on {\bf /dev/sg1}. Such
284 devices typically have several drives and a large number of tapes.
286 On FreeBSD systems, the changer device will typically be on {\bf /dev/pass0}
287 through {\bf /dev/passn}.
289 On Solaris, the changer device will typically be some file under {\bf
292 Please ensure that your Storage daemon has permission to access this
295 \item [Changer Command = \lt{}command\gt{}]
296 \index[sd]{Changer Command }
297 This record is used to specify the external program to call and what
298 arguments to pass to it. The command is assumed to be a standard program or
299 shell script that can be executed by the operating system. This command is
300 invoked each time that Bacula wishes to manipulate the autochanger. The
301 following substitutions are made in the {\bf command} before it is sent to
302 the operating system for execution:
307 %a = archive device name
308 %c = changer device name
309 %d = changer drive index base 0
312 %o = command (loaded, load, or unload)
319 An actual example for using {\bf mtx} with the {\bf mtx-changer} script (part
320 of the Bacula distribution) is:
324 Changer Command = "/etc/bacula/mtx-changer %c %o %S %a %d"
328 Where you will need to adapt the {\bf /etc/bacula} to be the actual path on
329 your system where the mtx-changer script resides. Details of the three
330 commands currently used by Bacula (loaded, load, unload) as well as the
331 output expected by Bacula are give in the {\bf Bacula Autochanger Interface}
334 \item [Maximum Changer Wait = \lt{}time\gt{}]
335 \index[sd]{Maximum Changer Wait }
336 This record is used to define the maximum amount of time that Bacula
337 will wait for an autoloader to respond to a command (e.g. load). The
338 default is set to 120 seconds. If you have a slow autoloader you may
339 want to set it longer.
341 If the autoloader program fails to respond in this time, it will be killed
342 and Bacula will request operator intervention.
344 \item [Drive Index = \lt{}number\gt{}]
345 \index[sd]{Drive Index }
346 This record allows you to tell Bacula to use the second or subsequent
347 drive in an autochanger with multiple drives. Since the drives are
348 numbered from zero, the second drive is defined by
357 To use the second drive, you need a second Device resource definition in the
358 Bacula configuration file. See the Multiple Drive section above in this
359 chapter for more information.
362 In addition, for proper functioning of the Autochanger, you must
363 define an Autochanger resource.
364 \input{autochangerres}
367 \section{An Example Configuration File}
368 \index[general]{Example Configuration File }
369 \index[general]{File!Example Configuration }
371 The following two resources implement an autochanger:
378 Changer Device = /dev/sg0
379 Changer Command = "/etc/bacula/mtx-changer %c %o %S %a %d"
385 Archive Device = /dev/nst0 # Normal archive device
388 AutomaticMount = yes;
394 where you will adapt the {\bf Archive Device}, the {\bf Changer Device}, and
395 the path to the {\bf Changer Command} to correspond to the values used on your
398 \section{A Multi-drive Example Configuration File}
399 \index[general]{Multi-drive Example Configuration File }
401 The following resources implement a multi-drive autochanger:
407 Device = Drive-1, Drive-2
408 Changer Device = /dev/sg0
409 Changer Command = "/etc/bacula/mtx-changer %c %o %S %a %d"
416 Archive Device = /dev/nst0 # Normal archive device
419 AutomaticMount = yes;
427 Archive Device = /dev/nst1 # Normal archive device
430 AutomaticMount = yes;
437 where you will adapt the {\bf Archive Device}, the {\bf Changer Device}, and
438 the path to the {\bf Changer Command} to correspond to the values used on your
441 \label{SpecifyingSlots}
442 \section{Specifying Slots When Labeling}
443 \index[general]{Specifying Slots When Labeling }
444 \index[general]{Labeling!Specifying Slots When }
446 If you add an {\bf Autochanger = yes} record to the Storage resource in your
447 Director's configuration file, the Bacula Console will automatically prompt
448 you for the slot number when the Volume is in the changer when
449 you {\bf add} or {\bf label} tapes for that Storage device. If your
450 {\bf mtx-changer} script is properly installed, Bacula will automatically
451 load the correct tape during the label command.
454 {\bf Autochanger = yes} in the Storage daemon's Device resource
455 as we have described above in
456 order for the autochanger to be used. Please see the
457 \ilink{Storage Resource}{Autochanger1} in the Director's chapter
459 \ilink{Device Resource}{Autochanger} in the Storage daemon
460 chapter for more details on these records.
462 Thus all stages of dealing with tapes can be totally automated. It is also
463 possible to set or change the Slot using the {\bf update} command in the
464 Console and selecting {\bf Volume Parameters} to update.
466 Even though all the above configuration statements are specified and correct,
467 Bacula will attempt to access the autochanger only if a {\bf slot} is non-zero
468 in the catalog Volume record (with the Volume name).
470 If your autochanger has barcode labels, you can label all the Volumes in
471 your autochanger one after another by using the {\bf label barcodes} command.
472 For each tape in the changer containing a barcode, Bacula will mount the tape
473 and then label it with the same name as the barcode. An appropriate Media
474 record will also be created in the catalog. Any barcode that begins with the
475 same characters as specified on the "CleaningPrefix=xxx" command, will be
476 treated as a cleaning tape, and will not be labeled. For example with:
478 Please note that Volumes must be pre-labeled to be automatically used in
479 the autochanger during a backup. If you do not have a barcode reader, this
480 is done manually (or via a script).
486 Cleaning Prefix = "CLN"
491 Any slot containing a barcode of CLNxxxx will be treated as a cleaning tape
492 and will not be mounted.
494 \section{Changing Cartridges}
495 \index[general]{Changing Cartridges }
496 If you wish to insert or remove cartridges in your autochanger or
497 you manually run the {\bf mtx} program, you must first tell Bacula
498 to release the autochanger by doing:
503 (change cartridges and/or run mtx)
508 If you do not do the unmount before making such a change, Bacula
509 will become completely confused about what is in the autochanger
510 and may stop function because it expects to have exclusive use
511 of the autochanger while it has the drive mounted.
515 \section{Dealing with Multiple Magazines}
516 \index[general]{Dealing with Multiple Magazines }
517 \index[general]{Magazines!Dealing with Multiple }
519 If you have several magazines or if you insert or remove cartridges from a
520 magazine, you should notify Bacula of this. By doing so, Bacula will as
521 a preference, use Volumes that it knows to be in the autochanger before
522 accessing Volumes that are not in the autochanger. This prevents unneeded
523 operator intervention.
525 If your autochanger has barcodes (machine readable tape labels), the task of
526 informing Bacula is simple. Every time, you change a magazine, or add or
527 remove a cartridge from the magazine, simply do
533 (insert new magazine)
539 in the Console program. This will cause Bacula to request the autochanger to
540 return the current Volume names in the magazine. This will be done without
541 actually accessing or reading the Volumes because the barcode reader does this
542 during inventory when the autochanger is first turned on. Bacula will ensure
543 that any Volumes that are currently marked as being in the magazine are marked
544 as no longer in the magazine, and the new list of Volumes will be marked as
545 being in the magazine. In addition, the Slot numbers of the Volumes will be
546 corrected in Bacula's catalog if they are incorrect (added or moved).
548 If you do not have a barcode reader on your autochanger, you have several
552 \item You can manually set the Slot and InChanger flag using the {\bf update
553 volume} command in the Console (quite painful).
555 \item You can issue a
563 command that will cause Bacula to read the label on each of the cartridges in
564 the magazine in turn and update the information (Slot, InChanger flag) in the
565 catalog. This is quite effective but does take time to load each cartridge
566 into the drive in turn and read the Volume label.
568 \item You can modify the mtx-changer script so that it simulates an
569 autochanger with barcodes. See below for more details.
573 \section{Simulating Barcodes in your Autochanger}
574 \index[general]{Autochanger!Simulating Barcodes in your }
575 \index[general]{Simulating Barcodes in your Autochanger }
577 You can simulate barcodes in your autochanger by making the {\bf mtx-changer}
578 script return the same information that an autochanger with barcodes would do.
579 This is done by commenting out the one and only line in the {\bf list)} case,
584 ${MTX} -f $ctl status | grep " *Storage Element [0-9]*:.*Full" | awk "{print \$3 \$4}" | sed "s/Full *\(:VolumeTag=\)*//"
588 at approximately line 99 by putting a \# in column one of that line, or by
589 simply deleting it. Then in its place add a new line that prints the contents
590 of a file. For example:
594 cat /etc/bacula/changer.volumes
598 Be sure to include a full path to the file, which can have any name. The
599 contents of the file must be of the following format:
610 Where the 1, 2, 3 are the slot numbers and Volume1, Volume2, ... are the
611 Volume names in those slots. You can have multiple files that represent the
612 Volumes in different magazines, and when you change magazines, simply copy the
613 contents of the correct file into your {\bf /etc/bacula/changer.volumes} file.
614 There is no need to stop and start Bacula when you change magazines, simply
615 put the correct data in the file, then run the {\bf update slots} command, and
616 your autochanger will appear to Bacula to be an autochanger with barcodes.
619 \section{The Full Form of the Update Slots Command}
620 \index[general]{Full Form of the Update Slots Command }
621 \index[general]{Command!Full Form of the Update Slots }
623 If you change only one cartridge in the magazine, you may not want to scan all
624 Volumes, so the {\bf update slots} command (as well as the {\bf update slots
625 scan} command) has the additional form:
629 update slots=n1,n2,n3-n4, ...
633 where the keyword {\bf scan} can be appended or not. The n1,n2, ... represent
634 Slot numbers to be updated and the form n3-n4 represents a range of Slot
635 numbers to be updated (e.g. 4-7 will update Slots 4,5,6, and 7).
637 This form is particularly useful if you want to do a scan (time expensive) and
638 restrict the update to one or two slots.
640 For example, the command:
644 update slots=1,6 scan
648 will cause Bacula to load the Volume in Slot 1, read its Volume label and
649 update the Catalog. It will do the same for the Volume in Slot 6. The command:
658 will read the barcoded Volume names for slots 1,2,3 and 6 and make the
659 appropriate updates in the Catalog. If you don't have a barcode reader or have
660 not modified the mtx-changer script as described above, the above command will
661 not find any Volume names so will do nothing.
664 \section{FreeBSD Issues}
665 \index[general]{Issues!FreeBSD }
666 \index[general]{FreeBSD Issues }
668 If you are having problems on FreeBSD when Bacula tries to select a tape, and
669 the message is {\bf Device not configured}, this is because FreeBSD has made
670 the tape device {\bf /dev/nsa1} disappear when there is no tape mounted in the
671 autochanger slot. As a consequence, Bacula is unable to open the device. The
672 solution to the problem is to make sure that some tape is loaded into the tape
673 drive before starting Bacula. This problem is corrected in Bacula versions
677 \ilink{ Tape Testing}{FreeBSDTapes} chapter of this manual for
678 {\bf important} information concerning your tape drive before doing the
680 \label{AutochangerTesting}
682 \section{Testing Autochanger and Adapting mtx-changer script}
683 \index[general]{Testing the Autochanger }
684 \index[general]{Adapting Your mtx-changer script}
687 Before attempting to use the autochanger with Bacula, it is preferable to
688 "hand-test" that the changer works. To do so, we suggest you do the
689 following commands (assuming that the {\bf mtx-changer} script is installed in
690 {\bf /etc/bacula/mtx-changer}):
694 \item [Make sure Bacula is not running.]
696 \item [/etc/bacula/mtx-changer \ /dev/sg0 \ list \ 0 \ /dev/nst0 \ 0]
697 \index[sd]{mtx-changer list}
699 This command should print:
711 or one number per line for each slot that is occupied in your changer, and
712 the number should be terminated by a colon ({\bf :}). If your changer has
713 barcodes, the barcode will follow the colon. If an error message is printed,
714 you must resolve the problem (e.g. try a different SCSI control device name
715 if {\bf /dev/sg0} is incorrect). For example, on FreeBSD systems, the
716 autochanger SCSI control device is generally {\bf /dev/pass2}.
718 \item [/etc/bacula/mtx-changer \ /dev/sg0 \ slots ]
719 \index[sd]{mtx-changer slots}
721 This command should return the number of slots in your autochanger.
723 \item [/etc/bacula/mtx-changer \ /dev/sg0 \ unload \ 1 \ /dev/nst0 \ 0 ]
724 \index[sd]{mtx-changer unload}
726 If a tape is loaded from slot 1, this should cause it to be unloaded.
728 \item [/etc/bacula/mtx-changer \ /dev/sg0 \ load \ 3 \ /dev/nst0 \ 0 ]
729 \index[sd]{mtx-changer load}
731 Assuming you have a tape in slot 3, it will be loaded into drive (0).
734 \item [/etc/bacula/mtx-changer \ /dev/sg0 \ loaded \ 0 \ /dev/nst0 \ 0]
735 \index[sd]{mtx-changer loaded}
738 Note, we have used an "illegal" slot number 0. In this case, it is simply
739 ignored because the slot number is not used. However, it must be specified
740 because the drive parameter at the end of the command is needed to select
743 \item [/etc/bacula/mtx-changer \ /dev/sg0 \ unload \ 3 /dev/nst0 \ 0]
745 will unload the tape into slot 3.
749 Once all the above commands work correctly, assuming that you have the right
750 {\bf Changer Command} in your configuration, Bacula should be able to operate
751 the changer. The only remaining area of problems will be if your autoloader
752 needs some time to get the tape loaded after issuing the command. After the
753 {\bf mtx-changer} script returns, Bacula will immediately rewind and read the
754 tape. If Bacula gets rewind I/O errors after a tape change, you will probably
755 need to insert a {\bf sleep 20} after the {\bf mtx} command, but be careful to
756 exit the script with a zero status by adding {\bf exit 0} after any additional
757 commands you add to the script. This is because Bacula checks the return
758 status of the script, which should be zero if all went well.
760 You can test whether or not you need a {\bf sleep} by putting the following
761 commands into a file and running it as a script:
766 /etc/bacula/mtx-changer /dev/sg0 unload 1 /dev/nst0 0
767 /etc/bacula/mtx-changer /dev/sg0 load 3 /dev/nst0 0
768 mt -f /dev/st0 rewind
773 If the above script runs, you probably have no timing problems. If it does not
774 run, start by putting a {\bf sleep 30} or possibly a {\bf sleep 60} in the
775 script just after the mtx-changer load command. If that works, then you should
776 move the sleep into the actual {\bf mtx-changer} script so that it will be
777 effective when Bacula runs.
779 A second problem that comes up with a small number of autochangers is that
780 they need to have the cartridge ejected before it can be removed. If this is
781 the case, the {\bf load 3} will never succeed regardless of how long you wait.
782 If this seems to be your problem, you can insert an eject just after the
783 unload so that the script looks like:
788 /etc/bacula/mtx-changer /dev/sg0 unload 1 /dev/nst0 0
789 mt -f /dev/st0 offline
790 /etc/bacula/mtx-changer /dev/sg0 load 3 /dev/nst0 0
791 mt -f /dev/st0 rewind
796 Obviously, if you need the {\bf offline} command, you should move it into the
797 mtx-changer script ensuring that you save the status of the {\bf mtx} command
798 or always force an {\bf exit 0} from the script, because Bacula checks the
799 return status of the script.
801 As noted earlier, there are several scripts in {\bf
802 \lt{}bacula-source\gt{}/examples/devices} that implement the above features,
803 so they may be a help to you in getting your script to work.
805 If Bacula complains "Rewind error on /dev/nst0. ERR=Input/output error." you
806 most likely need more sleep time in your {\bf mtx-changer} before returning to
807 Bacula after a load command has been completed.
811 \section{Using the Autochanger}
812 \index[general]{Using the Autochanger }
813 \index[general]{Autochanger!Using the }
815 Let's assume that you have properly defined the necessary Storage daemon
816 Device records, and you have added the {\bf Autochanger = yes} record to the
817 Storage resource in your Director's configuration file.
819 Now you fill your autochanger with say six blank tapes.
821 What do you do to make Bacula access those tapes?
823 One strategy is to prelabel each of the tapes. Do so by starting Bacula, then
824 with the Console program, enter the {\bf label} command:
829 Connecting to Director rufus:8101
830 1000 OK: rufus-dir Version: 1.26 (4 October 2002)
835 it will then print something like:
839 Using default Catalog name=BackupDB DB=bacula
840 The defined Storage resources are:
843 Select Storage resource (1-2): 1
847 I select the autochanger (1), and it prints:
851 Enter new Volume name: TestVolume1
852 Enter slot (0 for none): 1
856 where I entered {\bf TestVolume1} for the tape name, and slot {\bf 1} for the
864 Select the Pool (1-2): 1
868 I select the Default pool. This will be automatically done if you only have a
869 single pool, then Bacula will proceed to unload any loaded volume, load the
870 volume in slot 1 and label it. In this example, nothing was in the drive, so
875 Connecting to Storage daemon Autochanger at localhost:9103 ...
876 Sending label command ...
877 3903 Issuing autochanger "load slot 1" command.
878 3000 OK label. Volume=TestVolume1 Device=/dev/nst0
879 Media record for Volume=TestVolume1 successfully created.
880 Requesting mount Autochanger ...
881 3001 Device /dev/nst0 is mounted with Volume TestVolume1
887 You may then proceed to label the other volumes. The messages will change
888 slightly because Bacula will unload the volume (just labeled TestVolume1)
889 before loading the next volume to be labeled.
891 Once all your Volumes are labeled, Bacula will automatically load them as they
894 To "see" how you have labeled your Volumes, simply enter the {\bf list
895 volumes} command from the Console program, which should print something like
901 Using default Catalog name=BackupDB DB=bacula
905 Select the Pool (1-2): 1
906 +-------+----------+--------+---------+-------+--------+----------+-------+------+
907 | MedId | VolName | MedTyp | VolStat | Bites | LstWrt | VolReten | Recyc | Slot |
908 +-------+----------+--------+---------+-------+--------+----------+-------+------+
909 | 1 | TestVol1 | DDS-4 | Append | 0 | 0 | 30672000 | 0 | 1 |
910 | 2 | TestVol2 | DDS-4 | Append | 0 | 0 | 30672000 | 0 | 2 |
911 | 3 | TestVol3 | DDS-4 | Append | 0 | 0 | 30672000 | 0 | 3 |
913 +-------+----------+--------+---------+-------+--------+----------+-------+------+
919 \section{Barcode Support}
920 \index[general]{Support!Barcode }
921 \index[general]{Barcode Support }
923 Bacula provides barcode support with two Console commands, {\bf label
924 barcodes} and {\bf update slots}.
926 The {\bf label barcodes} will cause Bacula to read the barcodes of all the
927 cassettes that are currently installed in the magazine (cassette holder) using
928 the {\bf mtx-changer} {\bf list} command. Each cassette is mounted in turn and
929 labeled with the same Volume name as the barcode.
931 The {\bf update slots} command will first obtain the list of cassettes and
932 their barcodes from {\bf mtx-changer}. Then it will find each volume in turn
933 in the catalog database corresponding to the barcodes and set its Slot to
934 correspond to the value just read. If the Volume is not in the catalog, then
935 nothing will be done. This command is useful for synchronizing Bacula with the
936 current magazine in case you have changed magazines or in case you have moved
937 cassettes from one slot to another.
939 The {\bf Cleaning Prefix} statement can be used in the Pool resource to define
940 a Volume name prefix, which if it matches that of the Volume (barcode) will
941 cause that Volume to be marked with a VolStatus of {\bf Cleaning}. This will
942 prevent Bacula from attempting to write on the Volume.
946 \section{Bacula Autochanger Interface}
947 \index[general]{Interface!Bacula Autochanger }
948 \index[general]{Bacula Autochanger Interface }
950 Bacula calls the autochanger script that you specify on the {\bf Changer
951 Command} statement. Normally this script will be the {\bf mtx-changer} script
952 that we provide, but it can in fact be any program. The only requirement
953 for the script is that it must understand the commands that
954 Bacula uses, which are {\bf loaded}, {\bf load}, {\bf
955 unload}, {\bf list}, and {\bf slots}. In addition,
956 each of those commands must return the information in the precise format as
961 - Currently the changer commands used are:
962 loaded -- returns number of the slot that is loaded, base 1,
963 in the drive or 0 if the drive is empty.
964 load -- loads a specified slot (note, some autochangers
965 require a 30 second pause after this command) into
967 unload -- unloads the device (returns cassette to its slot).
968 list -- returns one line for each cassette in the autochanger
969 in the format <slot>:<barcode>. Where
970 the {\bf slot} is the non-zero integer representing
971 the slot number, and {\bf barcode} is the barcode
972 associated with the cassette if it exists and if you
973 autoloader supports barcodes. Otherwise the barcode
975 slots -- returns total number of slots in the autochanger.
979 Bacula checks the exit status of the program called, and if it is zero, the
980 data is accepted. If the exit status is non-zero, Bacula will print an
981 error message and request the tape be manually mounted on the drive.