4 \section*{What is Bacula?}
5 \label{_ChapterStart41}
6 \index[general]{Bacula!What is }
7 \index[general]{What is Bacula? }
8 \addcontentsline{toc}{section}{What is Bacula?}
10 {\bf Bacula} is a set of computer programs that permits you (or the system
11 administrator) to manage backup, recovery, and verification of computer data
12 across a network of computers of different kinds. In technical terms, it is a
13 network Client/Server based backup program. Bacula is relatively easy to use
14 and efficient, while offering many advanced storage management features that
15 make it easy to find and recover lost or damaged files. Due to its modular
16 design, Bacula is scalable from small single computer systems to systems
17 consisting of hundreds of computers located over a large network.
19 \subsection*{Who Needs Bacula?}
20 \index[general]{Who Needs Bacula? }
21 \index[general]{Bacula!Who Needs }
22 \addcontentsline{toc}{subsection}{Who Needs Bacula?}
24 If you are currently using a program such as {\bf tar}, {\bf dump}, or {\bf
25 bru} to backup your computer data, and you would like a network solution, more
26 flexibility, or catalog services, Bacula will most likely provide the
27 additional features you want. However, if you are new to Unix systems or do
28 not have offsetting experience with a sophisticated backup package, we do not
29 recommend using Bacula as it is much more difficult to setup and use than {\bf
32 If you want Bacula to behave like the above mentioned simple
33 programs and write over any tape that you put in the drive, then you will find
34 working with Bacula difficult. Bacula is designed to protect your data
35 following the rules you specify, and this means reusing a tape only
36 as the last resort. It is possible to ``force'' Bacula to write
37 over any tape in the drive, but it is easier and more efficient to use a
38 simpler program for that kind of operation.
40 If you are running {\bf Amanda} and would like a backup program that can write
41 to multiple volumes (i.e. is not limited by your tape drive capacity), Bacula
42 can most likely fill your needs. In addition, quite a number of our users
43 report that Bacula is simpler to setup and use than other equivalent programs.
45 If you are currently using a sophisticated commercial package such as Legato
46 Networker. ARCserveIT, Arkeia, or PerfectBackup+, you may be interested in
47 Bacula, which provides many of the same features, and is free software
48 available under the GNU Version 2 software license.
50 \subsection*{Bacula Components or Services}
51 \index[general]{Bacula Components or Services }
52 \index[general]{Services!Bacula Components or }
53 \addcontentsline{toc}{subsection}{Bacula Components or Services}
55 Bacula is made up of the following five major components or services:
57 \addcontentsline{lof}{figure}{Bacula Applications}
58 \includegraphics{./bacula-applications.eps}
59 (thanks to Aristedes Maniatis for this graphic and the one below)
64 {\bf Bacula Director} service consists of the program that supervises all the
65 backup, restore, verify and archive operations. The system administrator uses
66 the Bacula Director to schedule backups and to recover files. For more
67 details see the Director Services Daemon Design Document in the Bacula
68 Developer's Guild. The Director runs as a daemon or a service (i.e. in the
72 {\bf Bacula Console} services is the program that allows the administrator or
73 user to communicate with the {\bf Bacula Director} (see above). Currently,
74 the Bacula Console is available in three versions. The first and simplest is
75 to run the Console program in a shell window (i.e. TTY interface). Most
76 system administrators will find this completely adequate. The second version
77 is a GNOME GUI interface that for the moment (23 November 2003) is far from
78 complete, but quite functional as it has most the capabilities of the shell
79 Console. The third version is a wxWidgets GUI with an interactive file
80 restore. It also has most of the capabilities of the shell console, allows
81 command completion with tabulation, and gives you instant help about the
82 command you are typing. For more details see the
83 \ilink{Bacula Console Design Document}{_ChapterStart23}.
86 {\bf Bacula File} services (or Client program) is the software program that
87 is installed on the machine to be backed up. It is specific to the operating
88 system on which it runs and is responsible for providing the file attributes
89 and data when requested by the Director. The File services are also
90 responsible for the file system dependent part of restoring the file
91 attributes and data during a recovery operation. For more details see the
92 File Services Daemon Design Document in the Bacula Developer's Guide. This
93 program runs as a daemon on the machine to be backed up, and in some of the
94 documentation, the File daemon is referred to as the Client (for example in
95 Bacula's configuration file). In addition to Unix/Linux File daemons, there
96 is a Windows File daemon (normally distributed in binary format). The Windows
97 File daemon runs on all currently known Windows versions (95, 98, Me, NT,
101 {\bf Bacula Storage} services consist of the software programs that perform
102 the storage and recovery of the file attributes and data to the physical
103 backup media or volumes. In other words, the Storage daemon is responsible
104 for reading and writing your tapes (or other storage media, e.g. files). For
105 more details see the Storage Services Daemon Design Document in the Bacula
106 Developer's Guild. The Storage services runs as a daemon on the machine that
107 has the backup device (usually a tape drive).
110 {\bf Catalog} services are comprised of the software programs responsible for
111 maintaining the file indexes and volume databases for all files backed up.
112 The Catalog services permit the System Administrator or user to quickly
113 locate and restore any desired file. The Catalog services sets Bacula apart
114 from simple backup programs like tar and bru, because the catalog maintains a
115 record of all Volumes used, all Jobs run, and all Files saved, permitting
116 efficicient restoration and Volume management. Bacula currently supports
117 three different databases, MySQL, PostgreSQL, and SQLite, one of which must
118 be chosen when building {\bf Bacula}. There also exists an Internal database,
119 but it is no longer supported.
121 The three SQL databases currently supported (MySQL, PostgreSQL or SQLite)
122 provide quite a number of features, including rapid indexing, arbitrary
123 queries, and security. Although we plan to support other major SQL databases,
124 the current Bacula implementation interfaces only to MySQL, PostgreSQL and
125 SQLite. For the technical and porting details see the Catalog Services
126 Design Document in the developer's documented.
128 The RPMs for MySQL and PostgreSQL ship as part of the Linux RedHat
129 and several other releases, or building the rpms from the source is
131 \ilink{ Installing and Configuring MySQL}{_ChapterStart} chapter of
132 this document for the details. For more information on MySQL, please see:
133 \elink{www.mysql.com}{http://www.mysql.com}. Or see the
134 \ilink{ Installing and Configuring PostgreSQL}{_ChapterStart10}
135 chapter of this document for the details. For more information on PostgreSQL,
137 \elink{www.postgresql.org}{http://www.postgresql.org}.
139 Configuring and building SQLite is even easier. For the details of
140 configuring SQLite, please see the
141 \ilink{ Installing and Configuring SQLite}{_ChapterStart33} chapter
145 {\bf Bacula Monitor} services is the program that allows the administrator or
146 user to watch current status of {\bf Bacula Directors}, {\bf Bacula File
147 Daemons} and {\bf Bacula Storage Daemons} (see above). Currently, only a GTK+
148 version is available, which works with Gnome and KDE (or any window manager
149 that supports the FreeDesktop.org system tray standard).
152 To perform a successful save or restore, the following four daemons must be
153 configured and running: the Director daemon, the File daemon, the Storage
154 daemon, and MySQL, PostgreSQL or SQLite.
156 \subsection*{Bacula Configuration}
157 \index[general]{Configuration!Bacula }
158 \index[general]{Bacula Configuration }
159 \addcontentsline{toc}{subsection}{Bacula Configuration}
161 In order for Bacula to understand your system, what clients you want backed
162 up, and how, you must create a number of configuration files containing
163 resources (or objects). The following presents an overall picture of this:
165 \addcontentsline{lof}{figure}{Bacula Objects}
166 \includegraphics{./bacula-objects.eps}
168 \subsection*{Conventions Used in this Document}
169 \index[general]{Conventions Used in this Document }
170 \index[general]{Document!Conventions Used in this }
171 \addcontentsline{toc}{subsection}{Conventions Used in this Document}
173 {\bf Bacula} is in a state of evolution, and as a consequence, this manual
174 will not always agree with the code. If an item in this manual is preceded by
175 an asterisk (*), it indicates that the particular feature is not implemented.
176 If it is preceded by a plus sign (+), it indicates that the feature may be
177 partially implemented.
179 If you are reading this manual as supplied in a released version of the
180 software, the above paragraph holds true. If you are reading the online
181 version of the manual,
182 \elink{ www.bacula.org}{http://www.bacula.org}, please bear in
183 mind that this version describes the current version in development (in the
184 CVS) that may contain features not in the released version. Just the same, it
185 generally lags behind the code a bit.
187 \subsection*{Quick Start}
188 \index[general]{Quick Start }
189 \index[general]{Start!Quick }
190 \addcontentsline{toc}{subsection}{Quick Start}
192 To get Bacula up and running quickly, we recommend that you first scan the
193 Terminology section below, then quickly review the next chapter entitled
194 \ilink{The Current State of Bacula}{_ChapterStart2}, then the
195 \ilink{Getting Started with Bacula}{_ChapterStart37}, which will
196 give you a quick overview of getting Bacula running. After which, you should
197 proceed to the chapter on
198 \ilink{Installing Bacula}{_ChapterStart17}, then
199 \ilink{How to Configure Bacula}{_ChapterStart16}, and finally the
201 \ilink{ Running Bacula}{_ChapterStart1}.
203 \subsection*{Terminology}
204 \index[general]{Terminology }
205 \addcontentsline{toc}{subsection}{Terminology}
207 To facilitate communication about this project, we provide here the
208 definitions of the terminology that we use.
212 \item [Administrator]
213 \index[fd]{Administrator }
214 The person or persons responsible for administrating the Bacula system.
218 We use the term {\bf Backup} to refer to a Bacula Job that saves files.
220 \item [Bootstrap File]
221 \index[fd]{Bootstrap File }
222 The bootstrap file is an ASCII file containing a compact form of commands
223 that allow Bacula or the stand-alone file extraction utility ({\bf bextract})
224 to restore the contents of one or more Volumes, for example, the current
225 state of a system just backed up. With a bootstrap file, Bacula can restore
226 your system without a Catalog. You can create a bootstrap file from a Catalog
227 to extract any file or files you wish.
231 The Catalog is used to store summary information about the Jobs, Clients, and
232 Files that were backed up and on what Volume or Volumes. The information
233 saved in the Catalog permits the administrator or user to determine what jobs
234 were run, their status as well as the important characteristics of each file
235 that was backed up. The Catalog is an online resource, but does not contain
236 the data for the files backed up. Most of the information stored in the
237 catalog is also stored on the backup volumes (i.e. tapes). Of course, the
238 tapes will also have a copy of the file data in addition to the File Attributes
241 The catalog feature is one part of Bacula that distinguishes it from simple
242 backup and archive programs such as {\bf dump} and {\bf tar}.
246 In Bacula's terminology, the word Client refers to the machine being backed
247 up, and it is synonymous with the File services or File daemon, and quite
248 often, we refer to it as the FD. A Client is defined in a configuration file
253 The program that interfaces to the Director allowing the user or system
254 administrator to control Bacula.
258 Unix terminology for a program that is always present in the background to
259 carry out a designated task. On Windows systems, as well as some Linux
260 systems, daemons are called {\bf Services}.
263 \index[fd]{Directive }
264 The term directive is used to refer to a statement or a record within a
265 Resource in a configuration file that defines one specific thing. For
266 example, the {\bf Name} directive defines the name of the Resource.
269 \index[fd]{Director }
270 The main Bacula server daemon that schedules and directs all Bacula
271 operations. Occasionally, we refer to the Director as DIR.
274 \index[fd]{Differential }
275 A backup that includes all files changed since the last Full save started.
276 Note, other backup programs may define this differently.
278 \item [File Attributes]
279 \index[fd]{File Attributes }
280 The File Attributes are all the information necessary about a file to
281 identify it and all its properties such as size, creation date, modification
282 date, permissions, etc. Normally, the attributes are handled entirely by
283 Bacula so that the user never needs to be concerned about them. The
284 attributes do not include the file's data.
287 \index[fd]{File Daemon }
288 The daemon running on the client computer to be backed up. This is also
289 referred to as the File services, and sometimes as the Client services or the
296 A FileSet is a Resource contained in a configuration file that defines the
297 files to be backed up. It consists of a list of included files or
298 directories, a list of excluded files, and how the file is to be stored
299 (compression, encryption, signatures). For more details, see the
300 \ilink{FileSet Resource definition}{FileSetResource} in the
301 Director chapter of this document.
304 \index[fd]{Incremental }
305 A backup that includes all files changed since the last Full, Differential,
306 or Incremental backup started. It is normally specified on the {\bf Level}
307 directive within the Job resource definition, or in a Schedule resource.
313 A Bacula Job is a configuration resource that defines the work that Bacula
314 must perform to backup or restore a particular Client. It consists of the
315 {\bf Type} (backup, restore, verify, etc), the {\bf Level} (full,
316 incremental,...), the {\bf FileSet}, and {\bf Storage} the files are to be
317 backed up (Storage device, Media Pool). For more details, see the
318 \ilink{Job Resource definition}{JobResource} in the Director
319 chapter of this document.
323 The program that interfaces to the all the daemons allowing the user or
324 system administrator to monitor Bacula status.
327 \index[fd]{Resource }
328 A resource is a part of a configuration file that defines a specific unit of
329 information that is available to Bacula. It consists of several directives
330 (individual configuation statements). For example, the {\bf Job} resource
331 defines all the properties of a specific Job: name, schedule, Volume pool,
332 backup type, backup level, ...
336 A restore is a configuration resource that describes the operation of
337 recovering a file (lost or damaged) from backup media. It is the inverse of a
338 save, except that in most cases, a restore will normally have a small set of
339 files to restore, while normally a Save backs up all the files on the system.
340 Of course, after a disk crash, Bacula can be called upon to do a full
341 Restore of all files that were on the system.
344 \index[fd]{Schedule }
345 A Schedule is a configuration resource that defines when the Bacula Job will
346 be scheduled for execution. To use the Schedule, the Job resource will refer
347 to the name of the Schedule. For more details, see the
348 \ilink{Schedule Resource definition}{ScheduleResource} in the
349 Director chapter of this document.
353 This is Windows terminology for a {\bf daemon} -- see above. It is now
354 frequently used in Unix environments as well.
356 \item [Storage Coordinates]
357 \index[fd]{Storage Coordinates }
358 The information returned from the Storage Services that uniquely locates a
359 file on a backup medium. It consists of two parts: one part pertains to each
360 file saved, and the other part pertains to the whole Job. Normally, this
361 information is saved in the Catalog so that the user doesn't need specific
362 knowledge of the Storage Coordinates. The Storage Coordinates include the
363 File Attributes (see above) plus the unique location of the information on
366 \item [Storage Daemon]
367 \index[fd]{Storage Daemon }
368 The Storage daemon, sometimes referred to as the SD, is the code that writes
369 the attributes and data to a storage Volume (usually a tape or disk).
373 Normally refers to the internal conversation between the File daemon and the
374 Storage daemon. The File daemon opens a {\bf session} with the Storage daemon
375 to save a FileSet, or to restore it. A session has a one to one
376 correspondence to a Bacula Job (see above).
380 A verify is a job that compares the current file attributes to the attributes
381 that have previously been stored in the Bacula Catalog. This feature can be
382 used for detecting changes to critical system files similar to what {\bf
383 Tripwire} does. One of the major advantages of using Bacula to do this is
384 that on the machine you want protected such as a server, you can run just
385 the File daemon, and the Director, Storage daemon, and Catalog reside on a
386 different machine. As a consequence, if your server is ever compromised, it
387 is unlikely that your verification database will be tampered with.
389 Verify can also be used to check that the most recent Job data written to a
390 Volume agrees with what is stored in the Catalog (i.e. it compares the file
391 attributes), *or it can check the Volume contents against the original files
395 \index[fd]{*Archive }
396 An Archive operation is done after a Save, and it consists of removing the
397 Volumes on which data is saved from active use. These Volumes are marked as
398 Archived, and may no longer be used to save files. All the files contained
399 on an Archived Volume are removed from the Catalog. NOT YET IMPLEMENTED.
403 An Update operation causes the files on the remote system to be updated to be
404 the same as the host system. This is equivalent to an {\bf rdist} capability.
407 \item [Retention Period]
408 \index[fd]{Retention Period }
409 There are various kinds of retention periods that Bacula recognizes. The most
410 important are the {\bf File} Retention Period, {\bf Job} Retention Period,
411 and the {\bf Volume} Retention Period. Each of these retention periods
412 applies to the time that specific records will be kept in the Catalog
413 database. This should not be confused with the time that the data saved to a
416 The File Retention Period determines the time that File records are kept in
417 the catalog database. This period is important because the volume of the
418 database File records by far use the most storage space in the database. As a
419 consequence, you must ensure that regular ``pruning'' of the database file
420 records is done. (See the Console {\bf retention} command for more details on
423 The Job Retention Period is the length of time that Job records will be kept
424 in the database. Note, all the File records are tied to the Job that saved
425 those files. The File records can be purged leaving the Job records. In this
426 case, information will be available about the jobs that ran, but not the
427 details of the files that were backed up. Normally, when a Job record is
428 purged, all its File records will also be purged.
430 The Volume Retention Period is the minimum of time that a Volume will be
431 kept before it is reused. Bacula will normally never overwrite a Volume that
432 contains the only backup copy of a file. Under ideal conditions, the Catalog
433 would retain entries for all files backed up for all current Volumes. Once a
434 Volume is overwritten, the files that were backed up on that Volume are
435 automatically removed from the Catalog. However, if there is a very large
436 pool of Volumes or a Volume is never overwritten, the Catalog database may
437 become enormous. To keep the Catalog to a manageable size, the backup
438 information should be removed from the Catalog after the defined File Retention
439 Period. Bacula provides the mechanisms for the catalog to be automatically
440 pruned according to the retention periods defined.
444 A Scan operation causes the contents of a Volume or a series of Volumes to be
445 scanned. These Volumes with the information on which files they contain are
446 restored to the Bacula Catalog. Once the information is restored to the
447 Catalog, the files contained on those Volumes may be easily restored. This
448 function is particularly useful if certain Volumes or Jobs have exceeded
449 their retention period and have been pruned or purged from the Catalog.
450 Scanning data from Volumes into the Catalog is done by using the {\bf bscan}
452 \ilink{ bscan section}{bscan} of the Bacula Utilities Chapter of
453 this manual for more details.
457 A Volume is an archive unit, normally a tape or a named disk file where
458 Bacula stores the data from one or more backup jobs. All Bacula Volumes have
459 a software label written to the Volume by Bacula so that it identifies what
460 Volume it is really reading. (Normally there should be no confusion with disk
461 files, but with tapes, it is easy to mount the wrong one).
464 \subsection*{What Bacula is Not}
465 \index[general]{Not!What Bacula is }
466 \index[general]{What Bacula is Not }
467 \addcontentsline{toc}{subsection}{What Bacula is Not}
469 {\bf Bacula} is a backup, restore and verification program and is not a
470 complete disaster recovery system in itself, but it can be a key part of one
471 if you plan carefully and follow the instructions included in the
472 \ilink{ Disaster Recovery}{_ChapterStart38} Chapter of this manual.
474 With proper planning, as mentioned in the Disaster Recovery chapter {\bf
475 Bacula} can be a central component of your disaster recovery system. For
476 example, if you have created an emergency boot disk, a Bacula Rescue disk to
477 save the current partitioning information of your hard disk, and maintain a
478 complete Bacula backup, it is possible to completely recover your system from
479 ``bare metal'' that is starting from an empty disk.
481 If you have used the {\bf WriteBootstrap} record in your job or some other
482 means to save a valid bootstrap file, you will be able to use it to extract
483 the necessary files (without using the catalog or manually searching for the
486 \subsection*{Interactions Between the Bacula Services}
487 \index[general]{Interactions Between the Bacula Services }
488 \index[general]{Services!Interactions Between the Bacula }
489 \addcontentsline{toc}{subsection}{Interactions Between the Bacula Services}
491 The following block diagram shows the typical interactions between the Bacula
492 Services for a backup job. Each block represents in general a separate process
493 (normally a daemon). In general, the Director oversees the flow of
494 information. It also maintains the Catalog.
496 \addcontentsline{lof}{figure}{Interactions between Bacula Services}
497 \includegraphics{./flow.eps}
projects / bacula / docs / blob