5 \label{NewFeaturesChapter}
6 \index[general]{New Features}
8 This chapter presents the new features added to the development 2.5.x
9 versions to be released as Bacula version 3.0.0 near the end of 2008.
12 \index[general]{Accurate Backup}
14 As with most other backup programs, Bacula decides what files to backup for
15 Incremental and Differental backup by comparing the change (st\_ctime) and
16 modification (st\_mtime) times of the file to the time the last backup
17 completed. If one of those two times is different than from last backup time,
18 then the file will be backed up. This does not, however, permit tracking what
19 files have been deleted and will miss any file with an old time that may have
20 been restored or moved on the client filesystem.
22 \subsection{Accurate = \lt{}yes|no\gt{}}
23 If the {\bf Accurate = \lt{}yes|no\gt{}} directive is enabled (default no) in
24 the Job resource, the job will be run as an Accurate Job. For a {\bf Full}
25 backup, there is no difference, but for {\bf Differential} and {\bf
26 Incremental} backups, the Director will send a list of all previous files
27 backed up, and the File daemon will use that list to determine if any new files
28 have been added or or moved and if any files have been deleted. This allows
29 Bacula to make an accurate backup of your system to that point in time so that
30 if you do a restore, it will restore your system exactly. One note of caution
31 about using Accurate backup is that it requires more resources (CPU and memory)
32 on both the Director and the Client machines to create the list of previous
33 files backed up, to send that list to the File daemon, for the File daemon to
34 keep the list (possibly very big) in memory, and for the File daemon to do
35 comparisons between every file in the FileSet and the list.
39 \index[general]{Copy Jobs}
40 A new {\bf Copy} job type has been implemented. It is essentially
41 identical to the existing Migration feature with the exception that
42 the Job that is copied is left unchanged. This essentially creates
43 two identical copies of the same backup. The Copy Job runs without
44 using the File daemon by copying the data from the old backup Volume to
45 a different Volume in a different Pool. See the Migration documentation
46 for additional details.
48 \section{Virtual Backup (Vbackup)}
49 \index[general]{Virtual Backup}
50 \index[general]{Vbackup}
52 Bacula's virtual backup feature is often called Synthetic Backup or
53 Consolidation in other backup products. It permits you to consolidate
54 the previous Full backup plus the most recent Differential backup and any
55 subsequent Incremental backups into a new Full backup. This is accomplished
56 without contacting the client by reading the previous backup data and
57 writing it to a volume in a different pool.
59 In some respects the Vbackup feature works similar to a Migration job, in
60 that Bacula normally reads the data from the pool specified in the
61 Job resource, and writes it to the {\bf Next Pool} specified in the
62 Job resource. The input Storage resource and the Output Storage resource
65 The Vbackup is enabled on a Job by Job in the Job resource by specifying
66 a level of {\bf VirtualFull}.
68 A typical Job resource definition might look like the following:
82 # Default pool definition
86 Recycle = yes # Automatically recycle Volumes
87 AutoPrune = yes # Prune expired volumes
88 Volume Retention = 365d # one year
96 Recycle = yes # Automatically recycle Volumes
97 AutoPrune = yes # Prune expired volumes
98 Volume Retention = 365d # one year
102 # Definition of file storage device
109 Maximum Concurrent Jobs = 5
112 # Definition of DDS Virtual tape disk storage device
115 Address = localhost # N.B. Use a fully qualified name here
118 Media Type = DiskChangerMedia
119 Maximum Concurrent Jobs = 4
124 Then in bconsole or via a Run schedule, you would run the job as:
127 run job=MyBackup level=Full
128 run job=MyBackup level=Incremental
129 run job=MyBackup level=Differential
130 run job=MyBackup level=Incremental
131 run job=MyBackup level=Incremental
134 So providing there were changes between each of those jobs, you would end up
135 with a Full backup, a Differential, which includes the first Incremental
136 backup, then two Incremental backups. All the above jobs would be written to
137 the {\bf Default} pool.
139 To consolidate those backups into a new Full backup, you would run the
143 run job=MyBackup level=VirtualFull
146 And it would produce a new Full backup without using the client, and the output
147 would be written to the {\bf Full} Pool which uses the Diskchanger Storage.
149 \section{Duplicate Job Control}
150 \index[general]{Duplicate Jobs}
151 The new version of Bacula provides four new directives that
152 give additional control over what Bacula does if duplicate jobs
153 are started. A duplicate job in the sense we use it here means
154 a second or subsequent job with the same name starts. This
155 happens most frequently when the first job runs longer than expected because no
158 The four directives each take as an argument a {\bf yes} or {\bf no} value and
159 are specified in the Job resource.
163 \subsection{Allow Duplicate Jobs = \lt{}yes|no\gt{}}
164 If this directive is enabled duplicate jobs will be run. If
165 the directive is set to {\bf no} (default) then only one job of a given name
166 may run at one time, and the action that Bacula takes to ensure only
167 one job runs is determined by the other directives (see below).
169 \subsection{Allow Higher Duplicates = \lt{}yes|no\gt{}}
170 If this directive is set to {\bf yes} (default) the job with a higher
171 priority (lower priority number) will be permitted to run. If the
172 priorities of the two jobs are the same, the outcome is determined by
173 other directives (see below).
175 \subsection{Cancel Queued Duplicates = \lt{}yes|no\gt{}}
176 If this directive is set to {\bf yes} (default) any job that is
177 already queued to run but not yet running will be canceled.
179 \subsection{Cancel Running Duplicates = \lt{}yes|no\gt{}}
180 If this directive is set to {\bf yes} any job that is already running
181 will be canceled. The default is {\bf no}.
184 \section{TLS Authentication}
185 \index[general]{TLS Authentication}
186 In Bacula version 2.5.x and later, in addition to the normal Bacula
187 CRAM-MD5 authentication that is used to authenticate each Bacula
188 connection, you can specify that you want TLS Authentication as well,
189 which will provide more secure authentication.
191 This new feature uses Bacula's existing TLS code (normally used for
192 communications encryption) to do authentication. To use it, you must
193 specify all the TLS directives normally used to enable communications
194 encryption (TLS Enable, TLS Verify Peer, TLS Certificate, ...) and
197 \subsection{TLS Authenticate = yes}
199 TLS Authenticate = yes
202 in the main daemon configuration resource (Director for the Director,
203 Client for the File daemon, and Storage for the Storage daemon).
205 When {\bf TLS Authenticate} is enabled, after doing the CRAM-MD5
206 authentication, Bacula will do the normal TLS authentication, then TLS
207 encryption will be turned off.
209 If you want to encrypt communications data, do not turn on {\bf TLS
212 \section{bextract non-portable Win32 data}
213 \index[general]{bextract handles Win32 non-portable data}
214 {\bf bextract} has been enhanced to be able to restore
215 non-portable Win32 data to any OS. Previous versions were
216 unable to restore non-portable Win32 data to machines that
217 did not have the Win32 BackupRead and BackupWrite API calls.
219 \section{State File updated at Job Termination}
220 \index[general]{State File}
221 In previous versions of Bacula, the state file, which provides a
222 summary of previous jobs run in the {\bf status} command output was
223 updated only when Bacula terminated, thus if the daemon crashed, the
224 state file might not contain all the run data. This version of
225 the Bacula daemons updates the state file on each job termination.
227 \section{MaxFullInterval = \lt{}time-interval\gt{}}
228 \index[general]{MaxFullInterval}
229 The new Job resource directive {\bf Max Full Interval = \lt{}time-interval\gt{}}
230 can be used to specify the maximum time interval between {\bf Full} backup
231 jobs. When a job starts, if the time since the last Full backup is
232 greater than the specified interval, and the job would normally be an
233 {\bf Incremental} or {\bf Differential}, it will be automatically
234 upgraded to a {\bf Full} backup.
236 \section{MaxDiffInterval = \lt{}time-interval\gt{}}
237 \index[general]{MaxDiffInterval}
238 The new Job resource directive {\bf Max Diff Interval = \lt{}time-interval\gt{}}
239 can be used to specify the maximum time interval between {\bf Differential} backup
240 jobs. When a job starts, if the time since the last Differential backup is
241 greater than the specified interval, and the job would normally be an
242 {\bf Incremental}, it will be automatically
243 upgraded to a {\bf Differential} backup.
245 \section{Honor No Dump Flag = \lt{}yes|no\gt{}}
246 \index[general]{MaxDiffInterval}
247 On FreeBSD systems, each file has a {\bf no dump flag} that can be set
248 by the user, and when it is set it is an indication to backup programs
249 to not backup that particular file. This version of Bacula contains a
250 new Options directive within a FileSet resource, which instructs Bacula to
251 obey this flag. The new directive is:
254 Honor No Dump Flag = yes|no
257 The default value is {\bf no}.
260 \section{Ignore Dir = \lt{}filename-string\gt{}}
261 \index[general]{IgnoreDir}
262 The {\bf Ignore Dir = \lt{}filename\gt{}} is a new directive that can be added to the Include
263 section of the FileSet resource. If the specified
264 filename is found on the Client in any directory to be backed up,
265 the whole directory will be ignored (not backed up).
269 # List of files to be backed up
277 IgnoreDir = .excludeme
282 But in /home, there may be hundreds of directories of users and some
283 people want to indicate that they don't want to have certain
284 directories backed up. For example, with the above FileSet, if
285 the user or sysadmin creates a file named {\bf .excludeme} in
286 specific directories, such as
289 /home/user/www/cache/.excludeme
290 /home/user/temp/.excludeme
293 then Bacula will not backup the two directories named:
300 NOTE: subdirectories will not be backed up. That is, the directive
301 applies to the two directories in question and any children (be they
302 files, directories, etc).
306 \section{Bacula Plugins}
307 \index[general]{Plugin}
308 Support for shared object plugins has been implemented in the Linux
309 (and Unix) File daemon. The API will be documented separately in
310 the Developer's Guide or in a new document. For the moment, there is
311 a single plugin named {\bf bpipe} that allows an external program to
312 get control to backup and restore a file.
314 Plugins are also planned (partially implemented) in the Director and the
315 Storage daemon. The code is also implemented to work on Win32 machines,
316 but it has not yet been tested.
318 \subsection{Plugin Directory}
319 Each daemon (DIR, FD, SD) has a new {\bf Plugin Directory} directive that may
320 be added to the daemon definition resource. The directory takes a quoted
321 string argument, which is the name of the directory in which the daemon can
322 find the Bacula plugins. If this directive is not specified, Bacula will not
323 load any plugins. Since each plugin has a distinctive name, all the daemons
324 can share the same plugin directory.
328 \subsection{Plugin Options}
329 The {\bf Plugin Options} directive takes a quoted string
330 arguement (after the equal sign) and may be specified in the
331 Job resource. The options specified will be passed to the plugin
332 when it is run. The value defined in the Job resource can be modified
333 by the user when he runs a Job via the {\bf bconsole} command line
336 Note: this directive may be specified, but it is not yet passed to
337 the plugin (i.e. not fully implemented).
339 \subsection{Plugin Options ACL}
340 The {\bf Plugin Options ACL} directive may be specified in the
341 Director's Console resource. It functions as all the other ACL commands
342 do by permitting users running restricted consoles to specify a
343 {\bf Plugin Options} that overrides the one specified in the Job
344 definition. Without this directive restricted consoles may not modify
347 \subsection{Plugin = \lt{}plugin-command-string\gt{}}
348 The {\bf Plugin} directive is specified in the Include section of
349 a FileSet resource where you put your {\bf File = xxx} directives.
365 In the above example, when the File daemon is processing the directives
366 in the Include section, it will first backup all the files in {\bf /home}
367 then it will load the plugin named {\bf bpipe} (actually bpipe-dir.so) from
368 the Plugin Directory. The syntax and semantics of the Plugin directive
369 require the first part of the string up to the colon (:) to be the name
370 of the plugin. Everything after the first colon is ignored by the File daemon but
371 is passed to the plugin. Thus the plugin writer may define the meaning of the
372 rest of the string as he wishes.
374 Please see the next section for information about the {\bf bpipe} Bacula
377 \section{The bpipe Plugin}
378 The {\bf bpipe} plugin is provided in the directory src/plugins/fd/bpipe-fd.c of
379 the Bacula source distribution. When the plugin is compiled and linking into
380 the resulting dynamic shared object (DSO), it will have the name {\bf bpipe-fd.so}.
382 The purpose of the plugin is to provide an interface to any system program for
383 backup and restore. As specified above the {\bf bpipe} plugin is specified in
384 the Include section of your Job's FileSet resource. The full syntax of the
385 plugin directive as interpreted by the {\bf bpipe} plugin (each plugin is free
386 to specify the sytax as it wishes) is:
389 Plugin = "<field1>:<field2>:<field3>:<field4>"
394 \item {\bf field1} is the name of the plugin with the trailing {\bf -fd.so}
395 stripped off, so in this case, we would put {\bf bpipe} in this field.
397 \item {\bf field2} specifies the namespace, which for {\bf bpipe} is the
398 pseudo path and filename under which the backup will be saved. This pseudo
399 path and filename will be seen by the user in the restore file tree.
400 For example, if the value is {\bf /MYSQL/regress.sql}, the data
401 backed up by the plugin will be put under that "pseudo" path and filename.
402 You must be careful to choose a naming convention that is unique to avoid
403 a conflict with a path and filename that actually exists on your system.
405 \item {\bf field3} for the {\bf bpipe} plugin
406 specifies the "reader" program that is called by the plugin during
407 backup to read the data. {\bf bpipe} will call this program by doing a
410 \item {\bf field4} for the {\bf bpipe} plugin
411 specifies the "writer" program that is called by the plugin during
412 restore to write the data back to the filesystem.
415 Putting it all together, the full plugin directive line might look
419 Plugin = "bpipe:/MYSQL/regress.sql:mysqldump -f
420 --opt --databases bacula:mysql"
423 The directive has been split into two lines, but within the {\bf bacula-dir.conf} file
424 would be written on a single line.
426 This causes the File daemon to call the {\bf bpipe} plugin, which will write
427 its data into the "pseudo" file {\bf /MYSQL/regress.sql} by calling the
428 program {\bf mysqldump -f --opt --database bacula} to read the data during
429 backup. The mysqldump command outputs all the data for the database named
430 {\bf bacula}, which will be read by the plugin and stored in the backup.
431 During restore, the data that was backed up will be sent to the program
432 specified in the last field, which in this case is {\bf mysql}. When
433 {\bf mysql} is called, it will read the data sent to it by the plugn
434 then write it back to the same database from which it came ({\bf bacula}
437 The {\bf bpipe} plugin is a generic pipe program, that simply transmits
438 the data from a specified program to Bacula for backup, and then from Bacula to
439 a specified program for restore.
441 By using different command lines to {\bf bpipe},
442 you can backup any kind of data (ASCII or binary) depending
443 on the program called.
445 \section{libdbi framework}
446 As a general guideline, Bacula has support for a few catalog database drivers
447 coded natively by the Bacula team. With the libdbi implementation, which is a
448 Bacula driver that uses libdbi to access the catalog, we have an open field to
449 use many different kinds database engines following the needs of users.
451 The according to libdbi (http://libdbi.sourceforge.net/) project: libdbi
452 implements a database-independent abstraction layer in C, similar to the
453 DBI/DBD layer in Perl. Writing one generic set of code, programmers can
454 leverage the power of multiple databases and multiple simultaneous database
455 connections by using this framework.
457 Currently the libdbi driver in Bacula project only supports the same drivers
458 natively coded in Bacula. However the libdbi project has support for many
459 others database engines. You can view the list at
460 http://libdbi-drivers.sourceforge.net/. In the future all those drivers can be
461 supported by Bacula, however, they must be tested properly by the Bacula team.
463 Some of benefits of using libdbi are:
465 \item The possibility to use proprietary databases engines in which your
466 proprietary licenses prevent the Bacula team from developing the driver.
467 \item The possibility to use the drivers written for the libdbi project.
468 \item The possibility to use other database engines without recompiling Bacula
469 to use them. Just change one line in bacula-dir.conf
470 \item Abstract Database access, this is, unique point to code and profiling
471 catalog database access.
474 The following drivers have been tested:
476 \item PostgreSQL, with and without batch insert
477 \item Mysql, with and without batch insert
482 In the future, we will test and approve to use others databases engines
483 (proprietary or not) like DB2, Oracle, Microsoft SQL.
485 To compile Bacula to support libdbi we need to configure the code with the
486 --with-dbi and --with-dbi-driver=[database] ./configure options, where
487 [database] is the database engine to be used with Bacula (of course we can
488 change the driver in file bacula-dir.conf, see below). We must configure the
489 access port of the database engine with the option --with-db-port, because the
490 libdbi framework doesn't know the default access port of each database.
492 The next phase is checking (or configuring) the bacula-dir.conf, example:
496 dbdriver = dbi:mysql; dbaddress = 127.0.0.1; dbport = 3306
497 dbname = regress; user = regress; password = ""
501 The parameter {\bf dbdriver} indicates that we will use the driver dbi with a
502 mysql database. Currently the drivers supported by Bacula are: postgresql,
503 mysql, sqlite, sqlite3; these are the names that may be added to string "dbi:".
505 The following limitations apply when Bacula is set to use the libdbi framework:
506 - Not tested on the Win32 platform
507 - A little performance is lost if comparing with native database driver.
508 The reason is bound with the database driver provided by libdbi and the
509 simple fact that one more layer of code was added.
511 It is important to remember, when compiling Bacula with libdbi, the
512 following packages are needed:
514 \item libdbi version 1.0.0, http://libdbi.sourceforge.net/
515 \item libdbi-drivers 1.0.0, http://libdbi-drivers.sourceforge.net/
518 You can download them and compile them on your system or install the packages
519 from your OS distribution.
522 \section{Display Autochanger Content}
523 \index[general]{StatusSlots}
525 The {\bf status slots storage=\lt{}storage-name\gt{}} command displays autochanger content.
529 Slot | Volume Name | Status | Media Type | Pool |
530 ------+---------------+----------+-------------------+------------|
531 1 | 00001 | Append | DiskChangerMedia | Default |
532 2 | 00002 | Append | DiskChangerMedia | Default |
533 3*| 00003 | Append | DiskChangerMedia | Scratch |
538 If you an asterisk ({\bf *}) appears after the slot number, you must run an
539 {\bf update slots} command to synchronize autochanger content with your
542 \section{Miscellaneous}
543 \index[general]{Misc New Features}
545 \subsection{Allow Mixed Priority = \lt{}yes|no\g{}}
546 This directive is only implemented in version 2.5 and later. When
547 set to {\bf yes} (default {\bf no}), this job may run even if lower
548 priority jobs are already running. This means a high priority job
549 will not have to wait for other jobs to finish before starting.
550 The scheduler will only mix priorities when all running jobs have
553 Note that only higher priority jobs will start early. Suppose the
554 director will allow two concurrent jobs, and that two jobs with
555 priority 10 are running, with two more in the queue. If a job with
556 priority 5 is added to the queue, it will be run as soon as one of
557 the running jobs finishes. However, new priority 10 jobs will not
558 be run until the priority 5 job has finished.
560 \subsection{Bootstrap File Directive -- FileRegex}
561 {\bf FileRegex} is a new command that can be added to the bootstrap
562 (.bsr) file. The value is a regular expression. When specified, only
563 matching filenames will be restored.
565 During a restore, if all File records are pruned from the catalog
566 for a Job, normally Bacula can restore only all files saved. That
567 is there is no way using the catalog to select individual files.
568 With this new command, Bacula will ask if you want to specify a Regex
569 expression for extracting only a part of the full backup.
572 \subsection{Virtual Tape Emulation}
573 We now have a Virtual Tape emulator that allows us to run though 99.9\% of
574 the tape code but actually reading and writing to a disk file. Used with the
575 \textbf{disk-changer} script, you can now emulate an autochanger with 10 drives
576 and 700 slots. This feature is most useful in testing. It is enabled
577 by using {\bf Device Type = vtape} in the Storage daemon's Device
578 directive. This feature is only implemented on Linux machines.
580 \subsection{Bat Enhancements}
581 Bat (the Bacula Administration Tool) GUI program has been significantly
582 enhanced and stabilized. In particular, there are new table based status
583 commands; it can now be easily localized using Qt4 Linguist.
585 The Bat communications protocol has been significantly enhanced to improve
588 \subsection{RunScript Enhancements}
589 The {\bf RunScript} resource has been enhanced to permit multiple
590 commands per RunScript. Simply specify multiple {\bf Command} directives
597 Command = "/bin/echo test"
598 Command = "/bin/echo an other test"
599 Command = "/bin/echo 3 commands in the same runscript"
606 A new Client RunScript {\bf RunsWhen} keyword of {\bf AfterVSS} has been implemented, which
607 runs the command after the Volume Shadow Copy has been made.
609 Console commands can be specified within a RunScript by using:
610 {\bf Console = \lt{}command\gt{}}, however, this command has not been
611 carefully tested and debugged and is known to easily crash the Director.
612 We would appreciate feedback. Due to the recursive nature of this command, we
613 may remove it before the final release.
615 \subsection{Status Enhancements}
616 The bconsole {\bf status dir} output has been enhanced to indicate
617 Storage daemon job spooling and despooling activity.
619 \subsection{Connect Timeout}
620 The default connect timeout to the File
621 daemon has been set to 3 minutes. Previously it was 30 minutes.
623 \subsection{ftruncate for NFS Volumes}
624 If you write to a Volume mounted by NFS (say on a local file server),
625 in previous Bacula versions, when the Volume was recycled, it was not
626 properly truncated because NFS does not implement ftruncate (file
627 truncate). This is now corrected in the new version because we have
628 written code (actually a kind user) that deletes and recreates the Volume,
629 thus accomplishing the same thing as a truncate.
631 \subsection{Support for Ubuntu}
632 The new version of Bacula now recognizes the Ubuntu (and Kubuntu)
633 version of Linux, and thus now provides correct autostart routines.
634 Since Ubuntu officially supports Bacula, you can also obtain any
635 recent release of Bacula from the Ubuntu repositories.
637 \subsection{Recycle Pool = \lt{}pool-name\gt{}}
638 The new \textbf{RecyclePool} directive defines to which pool the Volume will
639 be placed (moved) when it is recycled. Without this directive, a Volume will
640 remain in the same pool when it is recycled. With this directive, it can be
641 moved automatically to any existing pool during a recycle. This directive is
642 probably most useful when defined in the Scratch pool, so that volumes will
643 be recycled back into the Scratch pool.
645 \subsection{FD Version}
646 The File daemon to Director protocol now includes a version
647 number, which although there is no visible change for users,
648 will help us in future versions automatically determine
649 if a File daemon is not compatible.
651 \subsection{Max Run Sched Time = \lt{}time-period-in-seconds\gt{}}
652 The time specifies the maximum allowed time that a job may run, counted from
653 when the job was scheduled. This can be useful to prevent jobs from running
654 during working hours. We can see it like \texttt{Max Start Delay + Max Run
657 \subsection{Max Wait Time = \lt{}time-period-in-seconds\gt{}}
659 Previous \textbf{MaxWaitTime} directives aren't working as expected, instead
660 of checking the maximum allowed time that a job may block for a resource,
661 those directives worked like \textbf{MaxRunTime}. Some users are reporting to
662 use \textbf{Incr/Diff/Full Max Wait Time} to control the maximum run time of
663 their job depending on the level. Now, they have to use
664 \textbf{Incr/Diff/Full Max Run Time}. \textbf{Incr/Diff/Full Max Wait Time}
665 directives are now deprecated.
667 \subsection{Incremental|Differential Max Wait Time = \lt{}time-period-in-seconds\gt{}}
668 Theses directives have been deprecated in favor of
669 \texttt{Incremental|Differential Max Run Time}.
671 \subsection{Max Run Time directives}
672 Using \textbf{Full/Diff/Incr Max Run Time}, it's now possible to specify the
673 maximum allowed time that a job can run depending on the level.
675 \addcontentsline{lof}{figure}{Job time control directives}
676 \includegraphics{\idir different_time.eps}
678 \subsection{Statistics Enhancements}
679 If you (or probably your boss) want to have statistics on your backups to
680 provide some \textit{Service Level Agreement} indicators, you could use a few
681 SQL queries on the Job table to report how many:
685 \item jobs have been successful
686 \item files have been backed up
690 However, these statistics are accurate only if your job retention is greater
691 than your statistics period. Ie, if jobs are purged from the catalog, you won't
694 Now, you can use the \textbf{update stats [days=num]} console command to fill
695 the JobStat table with new Job records. If you want to be sure to take in
696 account only \textbf{good jobs}, ie if one of your important job has failed but
697 you have fixed the problem and restarted it on time, you probably want to
698 delete the first \textit{bad} job record and keep only the successful one. For
699 that simply let your staff do the job, and update JobStat table after two or
700 three days depending on your organization using the \textbf{[days=num]} option.
702 These statistics records aren't used for restoring, but mainly for
703 capacity planning, billings, etc.
705 The Bweb interface provides a statistics module that can use this feature. You
706 can also use tools like Talend or extract information by yourself.
708 The {\textbf Statistics Retention = \lt{}time\gt{}} director directive defines
709 the length of time that Bacula will keep statistics job records in the Catalog
710 database after the Job End time. (In \texttt{JobStat} table) When this time
711 period expires, and if user runs \texttt{prune stats} command, Bacula will
712 prune (remove) Job records that are older than the specified period.
714 You can use the following Job resource in your nightly \textbf{BackupCatalog}
715 job to maintain statistics.
721 Console = "update stats days=3"
722 Console = "prune stats yes"
729 \subsection{SpoolSize = \lt{}size-specification-in-bytes\gt{}}
730 A new job directive permits to specify the spool size per job. This is used
731 in advanced job tunning. {\bf SpoolSize={\it bytes}}
734 \section{Building Bacula Plugins}
735 There is currently one sample program {\bf example-plugin-fd.c} and
736 one working plugin {\bf bpipe-fd.c} that can be found in the Bacula
737 {\bf src/plugins/fd} directory. Both are built with the following:
741 ./configure <your-options>
749 After building Bacula and changing into the src/plugins/fd directory,
750 the {\bf make} command will build the {\bf bpipe-fd.so} plugin, which
751 is a very useful and working program.
753 The {\bf make test} command will build the {\bf example-plugin-fd.so}
754 plugin and a binary named {\bf main}, which is build from the source
755 code located in {\bf src/filed/fd\_plugins.c}.
757 If you execute {\bf ./main}, it will load and run the example-plugin-fd
758 plugin simulating a small number of the calling sequences that Bacula uses
759 in calling a real plugin. This allows you to do initial testing of
760 your plugin prior to trying it with Bacula.
762 You can get a good idea of how to write your own plugin by first
763 studying the example-plugin-fd, and actually running it. Then
764 it can also be instructive to read the bpipe-fd.c code as it is
765 a real plugin, which is still rather simple and small.
767 When actually writing your own plugin, you may use the example-plugin-fd.c
768 code as a template for your code.
774 \chapter{Bacula FD Plugin API}
775 To write a Bacula plugin, you create a dynamic shared object
776 program (or dll on Win32) with a particular name and two
777 exported entry points, place it in the {\bf Plugins Directory}, which is defined in the
778 {\bf bacula-fd.conf} file in the {\bf Client} resource, and when the FD
779 starts, it will load all the plugins that end with {\bf -fd.so} (or {\bf -fd.dll}
780 on Win32) found in that directory.
782 Once the File daemon loads the plugins, it asks the OS for the
783 two entry points (loadPlugin and unloadPlugin) then calls the
784 {\bf loadPlugin} entry point (see below).
786 Bacula passes information to the plugin through this call and it gets
787 back information that it needs to use the plugin. Later, Bacula
788 will call particular functions that are defined by the
789 {\bf loadPlugin} interface.
791 When Bacula is finished with the plugin
792 (when Bacula is going to exit), it will call the {\bf unloadPlugin}
795 The two entry points are:
798 bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs)
805 both these external entry points to the shared object are defined as C entry points
806 to avoid name mangling complications with C++. However, the shared object
807 can actually be written in any language (preferrably C or C++) providing that it
808 follows C language calling conventions.
810 The definitions for {\bf bRC} and the arguments are {\bf
811 src/filed/fd-plugins.h} and so this header file needs to be included in
812 your plugin. It along with {\bf src/lib/plugins.h} define basically the whole
813 plugin interface. Within this header file, it includes the following
817 #include <sys/types.h>
819 #include "bc_types.h"
820 #include "lib/plugins.h"
821 #include <sys/stat.h>
824 Aside from the {\bf bc\_types.h} and {\bf confit.h} headers, the plugin definition uses the
825 minimum code from Bacula. The bc\_types.h file is required to ensure that
826 the data type defintions in arguments correspond to the Bacula core code.
828 The return codes are defined as:
832 bRC_Stop = 1, /* Stop calling other plugins */
833 bRC_Error = 2, /* Some kind of error */
834 bRC_More = 3, /* More files to backup */
839 At a future point in time, we hope to make the Bacula libbac.a into a
840 shared object so that the plugin can use much more of Bacula's
841 infrastructure, but for this first cut, we have tried to minimize the
842 dependence on Bacula.
845 As previously mentioned, the {\bf loadPlugin} entry point in the plugin
846 is called immediately after Bacula loads the plugin when the File daemon
847 itself is first starting. This entry point is only called once during the
848 execution of the File daemon. In calling the
849 plugin, the first two arguments are information from Bacula that
850 is passed to the plugin, and the last two arguments are information
851 about the plugin that the plugin must return to Bacula. The call is:
854 bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs)
857 and the arguments are:
861 This is information about Bacula in general. Currently, the only value
862 defined in the bInfo structure is the version, which is the Bacula plugin
863 interface version, currently defined as 1. The {\bf size} is set to the
864 byte size of the structure. The exact definition of the bInfo structure
865 as of this writing is:
868 typedef struct s_baculaInfo {
875 The bFuncs structure defines the callback entry points within Bacula
876 that the plugin can use register events, get Bacula values, set
877 Bacula values, and send messages to the Job output or debug output.
879 The exact definition as of this writing is:
881 typedef struct s_baculaFuncs {
884 bRC (*registerBaculaEvents)(bpContext *ctx, ...);
885 bRC (*getBaculaValue)(bpContext *ctx, bVariable var, void *value);
886 bRC (*setBaculaValue)(bpContext *ctx, bVariable var, void *value);
887 bRC (*JobMessage)(bpContext *ctx, const char *file, int line,
888 int type, time_t mtime, const char *fmt, ...);
889 bRC (*DebugMessage)(bpContext *ctx, const char *file, int line,
890 int level, const char *fmt, ...);
894 We will discuss these entry points and how to use them a bit later when
895 describing the plugin code.
899 When the loadPlugin entry point is called, the plugin must initialize
900 an information structure about the plugin and return a pointer to
901 this structure to Bacula.
903 The exact definition as of this writing is:
906 typedef struct s_pluginInfo {
909 const char *plugin_magic;
910 const char *plugin_license;
911 const char *plugin_author;
912 const char *plugin_date;
913 const char *plugin_version;
914 const char *plugin_description;
920 \item [version] is the current Bacula defined plugin interface version, currently
921 set to 1. If the interface version differs from the current version of
922 Bacula, the plugin will not be run (not yet implemented).
923 \item [plugin\_magic] is a pointer to the text string "*FDPluginData*", a
924 sort of sanity check. If this value is not specified, the plugin
925 will not be run (not yet implemented).
926 \item [plugin\_license] is a pointer to a text string that describes the
927 plugin license. Bacula will only accept compatible licenses (not yet
929 \item [plugin\_author] is a pointer to the text name of the author of the program.
930 This string can be anything but is generally the author's name.
931 \item [plugin\_date] is the pointer text string containing the date of the plugin.
932 This string can be anything but is generally some human readable form of
934 \item [plugin\_version] is a pointer to a text string containing the version of
935 the plugin. The contents are determined by the plugin writer.
936 \item [plugin\_description] is a pointer to a string describing what the
937 plugin does. The contents are determined by the plugin writer.
940 The pInfo structure must be defined in static memory because Bacula does not
941 copy it and may refer to the values at any time while the plugin is
942 loaded. All values must be supplied or the plugin will not run (not yet
943 implemented). All text strings must be either ASCII or UTF-8 strings that
944 are terminated with a zero byte.
947 When the loadPlugin entry point is called, the plugin must initialize
948 an entry point structure about the plugin and return a pointer to
949 this structure to Bacula. This structure contains pointer to each
950 of the entry points that the plugin must provide for Bacula. When
951 Bacula is actually running the plugin, it will call the defined
952 entry points at particular times. All entry points must be defined.
954 The pFuncs structure must be defined in static memory because Bacula does not
955 copy it and may refer to the values at any time while the plugin is
958 The exact definition as of this writing is:
961 typedef struct s_pluginFuncs {
964 bRC (*newPlugin)(bpContext *ctx);
965 bRC (*freePlugin)(bpContext *ctx);
966 bRC (*getPluginValue)(bpContext *ctx, pVariable var, void *value);
967 bRC (*setPluginValue)(bpContext *ctx, pVariable var, void *value);
968 bRC (*handlePluginEvent)(bpContext *ctx, bEvent *event, void *value);
969 bRC (*startBackupFile)(bpContext *ctx, struct save_pkt *sp);
970 bRC (*endBackupFile)(bpContext *ctx);
971 bRC (*startRestoreFile)(bpContext *ctx, const char *cmd);
972 bRC (*endRestoreFile)(bpContext *ctx);
973 bRC (*pluginIO)(bpContext *ctx, struct io_pkt *io);
974 bRC (*createFile)(bpContext *ctx, struct restore_pkt *rp);
975 bRC (*setFileAttributes)(bpContext *ctx, struct restore_pkt *rp);
979 The details of the entry points will be presented in
980 separate sections below.
984 \item [size] is the byte size of the structure.
985 \item [version] is the plugin interface version currently set to 1.
988 Sample code for loadPlugin:
990 bfuncs = lbfuncs; /* set Bacula funct pointers */
992 *pinfo = &pluginInfo; /* return pointer to our info */
993 *pfuncs = &pluginFuncs; /* return pointer to our functions */
998 where pluginInfo and pluginFuncs are statically defined structures.
999 See bpipe-fd.c for details.
1005 \section{Plugin Entry Points}
1006 This section will describe each of the entry points (subroutines) within
1007 the plugin that the plugin must provide for Bacula, when they are called
1008 and their arguments. As noted above, pointers to these subroutines are
1009 passed back to Bacula in the pFuncs structure when Bacula calls the
1010 loadPlugin() externally defined entry point.
1012 \subsection{newPlugin(bpContext *ctx)}
1013 This is the entry point that Bacula will call
1014 when a new "instance" of the plugin is created. This typically
1015 happens at the beginning of a Job. If 10 Jobs are running
1016 simultaneously, there will be at least 10 instances of the
1019 The bpContext structure will be passed to the plugin, and
1020 during this call, if the plugin needs to have its private
1021 working storage that is associated with the particular
1022 instance of the plugin, it should create it from the heap
1023 (malloc the memory) and store a pointer to
1024 its private working storage in the {\bf pContext} variable.
1025 Note: since Bacula is a multi-threaded program, you must not
1026 keep any variable data in your plugin unless it is truely meant
1027 to apply globally to the whole plugin. In addition, you must
1028 be aware that except the first and last call to the plugin
1029 (loadPlugin and unloadPlugin) all the other calls will be
1030 made by threads that correspond to a Bacula job. The
1031 bpContext that will be passed for each thread will remain the
1032 same throughout the Job thus you can keep your privat Job specific
1033 data in it ({\bf bContext}).
1036 typedef struct s_bpContext {
1037 void *pContext; /* Plugin private context */
1038 void *bContext; /* Bacula private context */
1043 This context pointer will be passed as the first argument to all
1044 the entry points that Bacula calls within the plugin. Needless
1045 to say, the plugin should not change the bContext variable, which
1046 is Bacula's private context pointer for this instance (Job) of this
1049 \subsection{freePlugin(bpContext *ctx)}
1050 This entry point is called when the
1051 this instance of the plugin is no longer needed (the Job is
1052 ending), and the plugin should release all memory it may
1053 have allocated for this particular instance (Job) i.e. the pContext.
1054 This is not the final termination
1055 of the plugin signaled by a call to {\bf unloadPlugin}.
1056 Any other instances (Job) will
1057 continue to run, and the entry point {\bf newPlugin} may be called
1058 again if other jobs start.
1060 \subsection{getPluginValue(bpContext *ctx, pVariable var, void *value)}
1061 Bacula will call this entry point to get
1062 a value from the plugin. This entry point is currently not called.
1064 \subsection{setPluginValue(bpContext *ctx, pVariable var, void *value)}
1065 Bacula will call this entry point to set
1066 a value in the plugin. This entry point is currently not called.
1068 \subsection{handlePluginEvent(bpContext *ctx, bEvent *event, void *value)}
1069 This entry point is called when Bacula
1070 encounters certain events (discussed below). This is, in fact, the
1071 main way that most plugins get control when a Job runs and how
1072 they know what is happening in the job. It can be likened to the
1073 {\bf RunScript} feature that calls external programs and scripts,
1074 and is very similar to the Bacula Python interface.
1075 When the plugin is called, Bacula passes it the pointer to an event
1076 structure (bEvent), which currently has one item, the eventType:
1079 typedef struct s_bEvent {
1084 which defines what event has been triggered, and for each event,
1085 Bacula will pass a pointer to a value associated with that event.
1086 If no value is associated with a particular event, Bacula will
1087 pass a NULL pointer, so the plugin must be careful to always check
1088 value pointer prior to dereferencing it.
1090 The current list of events are:
1096 bEventStartBackupJob = 3,
1097 bEventEndBackupJob = 4,
1098 bEventStartRestoreJob = 5,
1099 bEventEndRestoreJob = 6,
1100 bEventStartVerifyJob = 7,
1101 bEventEndVerifyJob = 8,
1102 bEventBackupCommand = 9,
1103 bEventRestoreCommand = 10,
1110 Most of the above are self-explanatory.
1113 \item [bEventJobStart] is called whenever a Job starts. The value
1114 passed is a pointer to a string that contains: "Jobid=nnn
1115 Job=job-name". Where nnn will be replaced by the JobId and job-name
1116 will be replaced by the Job name. The variable is temporary so if you
1117 need the values, you must copy them.
1119 \item [bEventJobEnd] is called whenever a Job ends. No value is passed.
1121 \item [bEventStartBackupJob] is called when a Backup Job begins. No value
1124 \item [bEventEndBackupJob] is called when a Backup Job ends. No value is
1127 \item [bEventStartRestoreJob] is called when a Restore Job starts. No value
1130 \item [bEventEndRestoreJob] is called when a Restore Job ends. No value is
1133 \item [bEventStartVerifyJob] is called when a Verify Job starts. No value
1136 \item [bEventEndVerifyJob] is called when a Verify Job ends. No value
1139 \item [bEventBackupCommand] is called prior to the bEventStartBackupJob and
1140 the plugin is passed the command string (everything after the equal sign
1141 in "Plugin =" as the value.
1143 Note, if you intend to backup a file, this is an important first point to
1144 write code that copies the command string passed into your pContext area
1145 so that you will know that a backup is being performed and you will know
1146 the full contents of the "Plugin =" command (i.e. what to backup and
1147 what virtual filename the user wants to call it.
1149 \item [bEventRestoreCommand] is called prior to the bEventStartRestoreJob and
1150 the plugin is passed the command string (everything after the equal sign
1151 in "Plugin =" as the value.
1153 See the notes above concerning backup and the command string. This is the
1154 point at which Bacula passes you the original command string that was
1155 specified during the backup, so you will want to save it in your pContext
1156 area for later use when Bacula calls the plugin again.
1158 \item [bEventLevel] is called when the level is set for a new Job. The value
1159 is a 32 bit integer stored in the void*, which represents the Job Level code.
1161 \item [bEventSince] is called when the since time is set for a new Job. The
1162 value is a time\_t time at which the last job was run.
1165 During each of the above calls, the plugin receives either no specific value or
1166 only one value, which in some cases may not be sufficient. However, knowing the
1167 context of the event, the plugin can call back to the Bacula entry points it
1168 was passed during the {\bf loadPlugin} call and get to a number of Bacula variables.
1169 (at the current time few Bacula variables are implemented, but it easily extended
1170 at a future time and as needs require).
1172 \subsection{startBackupFile(bpContext *ctx, struct save\_pkt *sp)}
1173 Called when beginning the backup of a file. Here Bacula provides you
1174 with a pointer to the {\bf save\_pkt} structure and you must fill in
1175 this packet with the "attribute" data of the file.
1179 int32_t pkt_size; /* size of this packet */
1180 char *fname; /* Full path and filename */
1181 char *link; /* Link name if any */
1182 struct stat statp; /* System stat() packet for file */
1183 int32_t type; /* FT_xx for this file */
1184 uint32_t flags; /* Bacula internal flags */
1185 bool portable; /* set if data format is portable */
1186 char *cmd; /* command */
1187 int32_t pkt_end; /* end packet sentinel */
1191 The second argument is a pointer to the {\bf save\_pkt} structure for the file
1192 to be backed up. The plugin is responsible for filling in all the fields
1193 of the {\bf save\_pkt}. If you are backing up
1194 a real file, then generally, the statp structure can be filled in by doing
1195 a {\bf stat} system call on the file.
1197 If you are backing up a database or
1198 something that is more complex, you might want to create a virtual file.
1199 That is a file that does not actually exist on the filesystem, but represents
1200 say an object that you are backing up. In that case, you need to ensure
1201 that the {\bf fname} string that you pass back is unique so that it
1202 does not conflict with a real file on the system, and you need to
1203 artifically create values in the statp packet.
1205 Example programs such as {\bf bpipe-fd.c} show how to set these fields.
1206 You must take care not to store pointers the stack in the pointer fields such
1207 as fname and link, because when you return from your function, your stack entries
1208 will be destroyed. The solution in that case is to malloc() and return the pointer
1209 to it. In order to not have memory leaks, you should store a pointer to all memory
1210 allocated in your pContext structure so that in subsequent calls or at termination,
1211 you can release it back to the system.
1213 Once the backup has begun, Bacula will call your plugin at the {\bf pluginIO}
1214 entry point to "read" the data to be backed up. Please see the {\bf bpipe-fd.c}
1215 plugin for how to do I/O.
1217 Example of filling in the save\_pkt as used in bpipe-fd.c:
1220 struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext;
1221 time_t now = time(NULL);
1222 sp->fname = p_ctx->fname;
1223 sp->statp.st_mode = 0700 | S_IFREG;
1224 sp->statp.st_ctime = now;
1225 sp->statp.st_mtime = now;
1226 sp->statp.st_atime = now;
1227 sp->statp.st_size = -1;
1228 sp->statp.st_blksize = 4096;
1229 sp->statp.st_blocks = 1;
1230 p_ctx->backup = true;
1234 Note: the filename to be created has already been created from the
1235 command string previously sent to the plugin and is in the plugin
1236 context (p\_ctx->fname) and is a malloc()ed string. This example
1237 creates a regular file (S\_IFREG), with various fields being created.
1239 In general, the sequence of commands issued from Bacula to the plugin
1240 to do a backup while processing the "Plugin = " directive are:
1243 \item generate a bEventBackupCommand event to the specified plugin
1244 and pass it the command string.
1245 \item make a startPluginBackup call to the plugin, which
1246 fills in the data needed in save\_pkt to save as the file
1247 attributes and to put on the Volume and in the catalog.
1248 \item call Bacula's internal save\_file() subroutine to save the specified
1249 file. The plugin will then be called at pluginIO() to "open"
1250 the file, and then to read the file data.
1251 Note, if you are dealing with a virtual file, the "open" operation
1252 is something the plugin does internally and it doesn't necessarily
1253 mean opening a file on the filesystem. For example in the case of
1254 the bpipe-fd.c program, it initiates a pipe to the requested program.
1255 Finally when the plugin signals to Bacula that all the data was read,
1256 Bacula will call the plugin with the "close" pluginIO() function.
1260 \subsection{endBackupFile(bpContext *ctx)}
1261 Called at the end of backing up a file. If the plugin's work
1262 is done, it should return bRC\_OK. If the plugin wishes to create another
1263 file and back it up, then it must return bRC\_More (not yet implemented).
1264 This is probably a good time to release any malloc()ed memory you used to
1265 pass back filenames.
1267 \subsection{startRestoreFile(bpContext *ctx, const char *cmd)}
1268 Not yet implemented.
1270 \subsection{createFile(bpContext *ctx, struct restore\_pkt *rp)}
1271 Called to create a file during a Restore job before restoring the data.
1272 This entry point is called before any I/O is done on the file. After
1273 this call, Bacula will call pluginIO() to open the file for write.
1276 restore\_pkt is passed to the plugin and is based on the data that was
1277 originally given by the plugin during the backup and the current user
1278 restore settings (e.g. where, RegexWhere, replace). This allows the
1279 plugin to first create a file (if necessary) so that the data can
1280 be transmitted to it. The next call to the plugin will be a
1281 pluginIO command with a request to open the file write-only.
1283 This call must return one of the following values:
1287 CF_SKIP = 1, /* skip file (not newer or something) */
1288 CF_ERROR, /* error creating file */
1289 CF_EXTRACT, /* file created, data to extract */
1290 CF_CREATED /* file created, no data to extract */
1294 in the restore\_pkt value {\bf create\_status}. For a normal file,
1295 unless there is an error, you must return {\bf CF\_EXTRACT}.
1299 struct restore_pkt {
1300 int32_t pkt_size; /* size of this packet */
1301 int32_t stream; /* attribute stream id */
1302 int32_t data_stream; /* id of data stream to follow */
1303 int32_t type; /* file type FT */
1304 int32_t file_index; /* file index */
1305 int32_t LinkFI; /* file index to data if hard link */
1306 uid_t uid; /* userid */
1307 struct stat statp; /* decoded stat packet */
1308 const char *attrEx; /* extended attributes if any */
1309 const char *ofname; /* output filename */
1310 const char *olname; /* output link name */
1311 const char *where; /* where */
1312 const char *RegexWhere; /* regex where */
1313 int replace; /* replace flag */
1314 int create_status; /* status from createFile() */
1315 int32_t pkt_end; /* end packet sentinel */
1320 \subsection{setFileAttributes(bpContext *ctx, struct restore\_pkt *rp)}
1321 This is call not yet implemented.
1323 See the definition of {\bf restre\_pkt} in the above section.
1325 \subsection{endRestoreFile(bpContext *ctx)}
1326 Called when done restoring a file.
1328 \subsection{pluginIO(bpContext *ctx, struct io\_pkt *io)}
1329 Called to do the input (backup) or output (restore) of data from or to a
1330 file. These routines simulate the Unix read(), write(), open(), close(),
1331 and lseek() I/O calls, and the arguments are passed in the packet and
1332 the return values are also placed in the packet. In addition for Win32
1333 systems the plugin must return two additional values (described below).
1345 int32_t pkt_size; /* Size of this packet */
1346 int32_t func; /* Function code */
1347 int32_t count; /* read/write count */
1348 mode_t mode; /* permissions for created files */
1349 int32_t flags; /* Open flags */
1350 char *buf; /* read/write buffer */
1351 const char *fname; /* open filename */
1352 int32_t status; /* return status */
1353 int32_t io_errno; /* errno code */
1354 int32_t lerror; /* Win32 error code */
1355 int32_t whence; /* lseek argument */
1356 boffset_t offset; /* lseek argument */
1357 bool win32; /* Win32 GetLastError returned */
1358 int32_t pkt_end; /* end packet sentinel */
1362 The particular Unix function being simulated is indicated by the {\bf func},
1363 which will have one of the IO\_OPEN, IO\_READ, ... codes listed above.
1364 The status code that would be returned from a Unix call is returned in
1365 {\bf status} for IO\_OPEN, IO\_CLOSE, IO\_READ, and IO\_WRITE. The return value for
1366 IO\_SEEK is returned in {\bf offset} which in general is a 64 bit value.
1368 When there is an error on Unix systems, you must always set io\_error, and
1369 on a Win32 system, you must always set win32, and the returned value from
1370 the OS call GetLastError() in lerror.
1372 For all except IO\_SEEK, {\bf status} is the return result. In general it is
1373 a positive integer unless there is an error in which case it is -1.
1375 The following describes each call and what you get and what you
1380 You will be passed fname, mode, and flags.
1381 You must set on return: status, and if there is a Unix error
1382 io\_errno must be set to the errno value, and if there is a
1383 Win32 error win32 and lerror.
1386 You will be passed: count, and buf (buffer of size count).
1387 You must set on return: status to the number of bytes
1388 read into the buffer (buf) or -1 on an error,
1389 and if there is a Unix error
1390 io\_errno must be set to the errno value, and if there is a
1391 Win32 error, win32 and lerror must be set.
1394 You will be passed: count, and buf (buffer of size count).
1395 You must set on return: status to the number of bytes
1396 written from the buffer (buf) or -1 on an error,
1397 and if there is a Unix error
1398 io\_errno must be set to the errno value, and if there is a
1399 Win32 error, win32 and lerror must be set.
1402 Nothing will be passed to you. On return you must set
1403 status to 0 on success and -1 on failure. If there is a Unix error
1404 io\_errno must be set to the errno value, and if there is a
1405 Win32 error, win32 and lerror must be set.
1408 You will be passed: offset, and whence. offset is a 64 bit value
1409 and is the position to seek to relative to whence. whence is one
1410 of the following SEEK\_SET, SEEK\_CUR, or SEEK\_END indicating to
1411 either to seek to an absolute possition, relative to the current
1412 position or relative to the end of the file.
1413 You must pass back in offset the absolute location to which you
1414 seeked. If there is an error, offset should be set to -1.
1415 If there is a Unix error
1416 io\_errno must be set to the errno value, and if there is a
1417 Win32 error, win32 and lerror must be set.
1419 Note: Bacula will call IO\_SEEK only when writing a sparse file.