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<B> Next:</B> <A NAME="tex2html1143"
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HREF="Current_State_Bacula.html">The Current State of</A>
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HREF="General_Index.html">Index</A></B>
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<!--Table of Child-Links-->
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<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
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<LI><A NAME="tex2html1144"
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HREF="What_is_Bacula.html#SECTION00041000000000000000">Who Needs Bacula?</A>
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<LI><A NAME="tex2html1145"
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HREF="What_is_Bacula.html#SECTION00042000000000000000">Bacula Components or Services</A>
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<LI><A NAME="tex2html1146"
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HREF="What_is_Bacula.html#SECTION00043000000000000000">Bacula Configuration</A>
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<LI><A NAME="tex2html1147"
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HREF="What_is_Bacula.html#SECTION00044000000000000000">Conventions Used in this Document</A>
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<LI><A NAME="tex2html1148"
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HREF="What_is_Bacula.html#SECTION00045000000000000000">Quick Start</A>
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<LI><A NAME="tex2html1149"
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HREF="What_is_Bacula.html#SECTION00046000000000000000">Terminology</A>
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<LI><A NAME="tex2html1150"
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HREF="What_is_Bacula.html#SECTION00047000000000000000">What Bacula is Not</A>
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<LI><A NAME="tex2html1151"
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HREF="What_is_Bacula.html#SECTION00048000000000000000">Interactions Between the Bacula Services</A>
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<!--End of Table of Child-Links-->
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<H1><A NAME="SECTION00040000000000000000"></A>
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<A NAME="_ChapterStart41"></A>
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<B>Bacula</B> is a set of computer programs that permits you (or the system
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administrator) to manage backup, recovery, and verification of computer data
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across a network of computers of different kinds. Bacula can also run entirely
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upon a single computer, and can backup to various types of media, including tape
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In technical terms, it is a
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network Client/Server based backup program. Bacula is relatively easy to use
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and efficient, while offering many advanced storage management features that
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make it easy to find and recover lost or damaged files. Due to its modular
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design, Bacula is scalable from small single computer systems to systems
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consisting of hundreds of computers located over a large network.
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<H2><A NAME="SECTION00041000000000000000">
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Who Needs Bacula?</A>
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If you are currently using a program such as <B>tar</B>, <B>dump</B>, or <B>bru</B> to backup your computer data, and you would like a network solution, more
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flexibility, or catalog services, Bacula will most likely provide the
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additional features you want. However, if you are new to Unix systems or do
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not have offsetting experience with a sophisticated backup package, we do not
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recommend using Bacula as it is much more difficult to setup and use than <B>tar</B> or <B>dump</B>.
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If you want Bacula to behave like the above mentioned simple
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programs and write over any tape that you put in the drive, then you will find
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working with Bacula difficult. Bacula is designed to protect your data
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following the rules you specify, and this means reusing a tape only
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as the last resort. It is possible to "force" Bacula to write
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over any tape in the drive, but it is easier and more efficient to use a
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simpler program for that kind of operation.
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If you are running <B>Amanda</B> and would like a backup program that can write
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to multiple volumes (i.e. is not limited by your tape drive capacity), Bacula
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can most likely fill your needs. In addition, quite a number of our users
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report that Bacula is simpler to setup and use than other equivalent programs.
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If you are currently using a sophisticated commercial package such as Legato
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Networker. ARCserveIT, Arkeia, or PerfectBackup+, you may be interested in
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Bacula, which provides many of the same features, and is free software
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available under the GNU Version 2 software license.
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<H2><A NAME="SECTION00042000000000000000">
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Bacula Components or Services</A>
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Bacula is made up of the following five major components or services:
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WIDTH="539" HEIGHT="693" ALIGN="BOTTOM" BORDER="0"
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SRC="bacula-applications.png"
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ALT="\includegraphics{./bacula-applications.eps}">
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(thanks to Aristedes Maniatis for this graphic and the one below)
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<LI><A NAME="DirDef"></A> <B>Bacula Director</B> service consists of the program that supervises
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all the backup, restore, verify and archive operations. The system
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administrator uses the Bacula Director to schedule backups and to
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recover files. For more details see the Director Services Daemon Design
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Document in the Bacula Developer's Guide. The Director runs as a daemon
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or a service (i.e. in the background).
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<LI><A NAME="UADef"></A> <B>Bacula Console</B> services is the program that allows the
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administrator or user to communicate with the <B>Bacula Director</B> (see
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above). Currently, the Bacula Console is available in three versions.
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The first and simplest is to run the Console program in a shell window
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(i.e. TTY interface). Most system administrators will find this
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completely adequate. The second version is a GNOME GUI interface that
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is far from complete, but quite functional as it has most the
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capabilities of the shell Console. The third version is a wxWidgets GUI
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with an interactive file restore. It also has most of the capabilities
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of the shell console, allows command completion with tabulation, and
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gives you instant help about the command you are typing. For more
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details see the <A HREF="Bacula_Console.html#_ConsoleChapter">Bacula Console Design Document</A>.
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<LI><A NAME="FDDef"></A> <B>Bacula File</B> services (or Client program) is the software program
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that is installed on the machine to be backed up. It is specific to the
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operating system on which it runs and is responsible for providing the
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file attributes and data when requested by the Director. The File
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services are also responsible for the file system dependent part of
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restoring the file attributes and data during a recovery operation. For
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more details see the File Services Daemon Design Document in the Bacula
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Developer's Guide. This program runs as a daemon on the machine to be
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backed up, and in some of the documentation, the File daemon is referred
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to as the Client (for example in Bacula's configuration file). In
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addition to Unix/Linux File daemons, there is a Windows File daemon
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(normally distributed in binary format). The Windows File daemon runs
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on current Windows versions (NT, 2000, XP, 2003, and possibly Me and
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<LI><A NAME="SDDef"></A> <B>Bacula Storage</B> services consist of the software programs that
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perform the storage and recovery of the file attributes and data to the
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physical backup media or volumes. In other words, the Storage daemon is
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responsible for reading and writing your tapes (or other storage media,
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e.g. files). For more details see the Storage Services Daemon Design
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Document in the Bacula Developer's Guild. The Storage services runs as
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a daemon on the machine that has the backup device (usually a tape
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<LI><A NAME="DBDefinition"></A> <B>Catalog</B> services are comprised of the software programs
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responsible for maintaining the file indexes and volume databases for
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all files backed up. The Catalog services permit the System
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Administrator or user to quickly locate and restore any desired file.
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The Catalog services sets Bacula apart from simple backup programs like
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tar and bru, because the catalog maintains a record of all Volumes used,
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all Jobs run, and all Files saved, permitting efficient restoration and
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Volume management. Bacula currently supports three different databases,
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MySQL, PostgreSQL, and SQLite, one of which must be chosen when building
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The three SQL databases currently supported (MySQL, PostgreSQL or
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SQLite) provide quite a number of features, including rapid indexing,
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arbitrary queries, and security. Although we plan to support other
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major SQL databases, the current Bacula implementation interfaces only
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to MySQL, PostgreSQL and SQLite. For the technical and porting details
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see the Catalog Services Design Document in the developer's documented.
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The RPMs for MySQL and PostgreSQL ship as part of the Linux RedHat and
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several other releases. Alternatively, building the rpms from the
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source is quite easy, see the <A HREF="Installing_Configurin_MySQL.html#_ChapterStart"> Installing and Configuring
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MySQL</A> chapter of this document for the details. For
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more information on MySQL, please see:
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HREF="http://www.mysql.com">www.mysql.com</A>. Or see the <A HREF="Installi_Configur_PostgreS.html#_ChapterStart10">
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Installing and Configuring PostgreSQL</A> chapter of this
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document for the details. For more information on PostgreSQL, please
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see: <A NAME="tex2html2"
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HREF="http://www.postgresql.org">www.postgresql.org</A>.
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Configuring and building SQLite is even easier. For the details of
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configuring SQLite, please see the <A HREF="Installin_Configuri_SQLite.html#_ChapterStart33"> Installing and Configuring
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SQLite</A> chapter of this document.
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<LI><A NAME="MonDef"></A> <B>Bacula Monitor</B> services is the program that allows the
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administrator or user to watch current status of <B>Bacula Directors</B>,
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<B>Bacula File Daemons</B> and <B>Bacula Storage Daemons</B> (see above).
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Currently, only a GTK+ version is available, which works with Gnome and
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KDE (or any window manager that supports the FreeDesktop.org system tray
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To perform a successful save or restore, the following four daemons must be
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configured and running: the Director daemon, the File daemon, the Storage
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daemon, and MySQL, PostgreSQL or SQLite.
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<H2><A NAME="SECTION00043000000000000000">
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Bacula Configuration</A>
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In order for Bacula to understand your system, what clients you want backed
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up, and how, you must create a number of configuration files containing
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resources (or objects). The following presents an overall picture of this:
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SRC="bacula-objects.png"
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ALT="\includegraphics{./bacula-objects.eps}">
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<H2><A NAME="SECTION00044000000000000000">
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Conventions Used in this Document</A>
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<B>Bacula</B> is in a state of evolution, and as a consequence, this manual
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will not always agree with the code. If an item in this manual is preceded by
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an asterisk (*), it indicates that the particular feature is not implemented.
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If it is preceded by a plus sign (+), it indicates that the feature may be
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partially implemented.
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If you are reading this manual as supplied in a released version of the
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software, the above paragraph holds true. If you are reading the online
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version of the manual,
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HREF="http://www.bacula.org">www.bacula.org</A>, please bear in
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mind that this version describes the current version in development (in the
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CVS) that may contain features not in the released version. Just the same, it
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generally lags behind the code a bit.
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<H2><A NAME="SECTION00045000000000000000">
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To get Bacula up and running quickly, we recommend that you first scan the
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Terminology section below, then quickly review the next chapter entitled
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<A HREF="Current_State_Bacula.html#_ChapterStart2">The Current State of Bacula</A>, then the
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<A HREF="Getting_Started_with_Bacula.html#_ChapterStart37">Getting Started with Bacula</A>, which will
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give you a quick overview of getting Bacula running. After which, you should
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proceed to the chapter on
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<A HREF="Installing_Bacula.html#_ChapterStart17">Installing Bacula</A>, then
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<A HREF="Customizin_Configurat_Files.html#_ChapterStart16">How to Configure Bacula</A>, and finally the
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<A HREF="Brief_Tutorial.html#_ChapterStart1"> Running Bacula</A>.
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<H2><A NAME="SECTION00046000000000000000">
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To facilitate communication about this project, we provide here the
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definitions of the terminology that we use.
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<DT><STRONG>Administrator</STRONG></DT>
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<DD><A NAME="178"></A>
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The person or persons responsible for administrating the Bacula system.
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<DT><STRONG>Backup</STRONG></DT>
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<DD><A NAME="179"></A>
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We use the term <B>Backup</B> to refer to a Bacula Job that saves files.
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<DT><STRONG>Bootstrap File</STRONG></DT>
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<DD><A NAME="181"></A>
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The bootstrap file is an ASCII file containing a compact form of
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commands that allow Bacula or the stand-alone file extraction utility
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(<B>bextract</B>) to restore the contents of one or more Volumes, for
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example, the current state of a system just backed up. With a bootstrap
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file, Bacula can restore your system without a Catalog. You can create
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a bootstrap file from a Catalog to extract any file or files you wish.
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<DT><STRONG>Catalog</STRONG></DT>
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<DD><A NAME="183"></A>
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The Catalog is used to store summary information about the Jobs,
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Clients, and Files that were backed up and on what Volume or Volumes.
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The information saved in the Catalog permits the administrator or user
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to determine what jobs were run, their status as well as the important
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characteristics of each file that was backed up, and most importantly,
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it permits you to choose what files to restore.
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online resource, but does not contain the data for the files backed up.
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Most of the information stored in the catalog is also stored on the
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backup volumes (i.e. tapes). Of course, the tapes will also have a
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copy of the file data in addition to the File Attributes (see below).
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The catalog feature is one part of Bacula that distinguishes it from
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simple backup and archive programs such as <B>dump</B> and <B>tar</B>.
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<DT><STRONG>Client</STRONG></DT>
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<DD><A NAME="186"></A>
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In Bacula's terminology, the word Client refers to the machine being
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backed up, and it is synonymous with the File services or File daemon,
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and quite often, we refer to it as the FD. A Client is defined in a
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configuration file resource.
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<DT><STRONG>Console</STRONG></DT>
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<DD><A NAME="187"></A>
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The program that interfaces to the Director allowing the user or system
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administrator to control Bacula.
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<DT><STRONG>Daemon</STRONG></DT>
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<DD><A NAME="188"></A>
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Unix terminology for a program that is always present in the background to
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carry out a designated task. On Windows systems, as well as some Linux
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systems, daemons are called <B>Services</B>.
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<DT><STRONG>Directive</STRONG></DT>
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<DD><A NAME="190"></A>
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The term directive is used to refer to a statement or a record within a
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Resource in a configuration file that defines one specific thing. For
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example, the <B>Name</B> directive defines the name of the Resource.
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<DT><STRONG>Director</STRONG></DT>
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<DD><A NAME="192"></A>
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The main Bacula server daemon that schedules and directs all Bacula
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operations. Occasionally, we refer to the Director as DIR.
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<DT><STRONG>Differential</STRONG></DT>
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<DD><A NAME="193"></A>
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A backup that includes all files changed since the last Full save started.
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Note, other backup programs may define this differently.
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<DT><STRONG>File Attributes</STRONG></DT>
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<DD><A NAME="194"></A>
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The File Attributes are all the information necessary about a file to
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identify it and all its properties such as size, creation date, modification
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date, permissions, etc. Normally, the attributes are handled entirely by
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Bacula so that the user never needs to be concerned about them. The
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attributes do not include the file's data.
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<DT><STRONG>File Daemon</STRONG></DT>
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<DD><A NAME="195"></A>
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The daemon running on the client computer to be backed up. This is also
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referred to as the File services, and sometimes as the Client services or the
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<A NAME="FileSetDef"></A></DD>
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<DT><STRONG>FileSet</STRONG></DT>
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<DD><A NAME="197"></A>
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A FileSet is a Resource contained in a configuration file that defines
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the files to be backed up. It consists of a list of included files or
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directories, a list of excluded files, and how the file is to be stored
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(compression, encryption, signatures). For more details, see the
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<A HREF="Configuring_Director.html#FileSetResource">FileSet Resource definition</A> in the Director
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chapter of this document.
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<DT><STRONG>Incremental</STRONG></DT>
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<DD><A NAME="200"></A>
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A backup that includes all files changed since the last Full, Differential,
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or Incremental backup started. It is normally specified on the <B>Level</B>
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directive within the Job resource definition, or in a Schedule resource.
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<A NAME="JobDef"></A></DD>
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<DT><STRONG>Job</STRONG></DT>
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<DD><A NAME="203"></A>
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A Bacula Job is a configuration resource that defines the work that
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Bacula must perform to backup or restore a particular Client. It
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consists of the <B>Type</B> (backup, restore, verify, etc), the <B> Level</B> (full, incremental,...), the <B>FileSet</B>, and <B>Storage</B> the
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files are to be backed up (Storage device, Media Pool). For more
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details, see the <A HREF="Configuring_Director.html#JobResource">Job Resource definition</A> in the
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Director chapter of this document.
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<DT><STRONG>Monitor</STRONG></DT>
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<DD><A NAME="210"></A>
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The program that interfaces to all the daemons allowing the user or
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system administrator to monitor Bacula status.
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<DT><STRONG>Resource</STRONG></DT>
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<DD><A NAME="211"></A>
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A resource is a part of a configuration file that defines a specific
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unit of information that is available to Bacula. It consists of several
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directives (individual configuration statements). For example, the <B> Job</B> resource defines all the properties of a specific Job: name,
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schedule, Volume pool, backup type, backup level, ...
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<DT><STRONG>Restore</STRONG></DT>
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<DD><A NAME="213"></A>
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A restore is a configuration resource that describes the operation of
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recovering a file from backup media. It is the inverse of a save,
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except that in most cases, a restore will normally have a small set of
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files to restore, while normally a Save backs up all the files on the
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system. Of course, after a disk crash, Bacula can be called upon to do
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a full Restore of all files that were on the system.
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<DT><STRONG>Schedule</STRONG></DT>
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<DD><A NAME="214"></A>
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A Schedule is a configuration resource that defines when the Bacula Job
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will be scheduled for execution. To use the Schedule, the Job resource
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will refer to the name of the Schedule. For more details, see the
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<A HREF="Configuring_Director.html#ScheduleResource">Schedule Resource definition</A> in the Director
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chapter of this document.
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<DT><STRONG>Service</STRONG></DT>
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<DD><A NAME="217"></A>
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This is Windows terminology for a <B>daemon</B> -- see above. It is now
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frequently used in Unix environments as well.
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<DT><STRONG>Storage Coordinates</STRONG></DT>
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<DD><A NAME="219"></A>
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The information returned from the Storage Services that uniquely locates
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a file on a backup medium. It consists of two parts: one part pertains
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to each file saved, and the other part pertains to the whole Job.
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Normally, this information is saved in the Catalog so that the user
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doesn't need specific knowledge of the Storage Coordinates. The Storage
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Coordinates include the File Attributes (see above) plus the unique
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location of the information on the backup Volume.
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<DT><STRONG>Storage Daemon</STRONG></DT>
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<DD><A NAME="220"></A>
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The Storage daemon, sometimes referred to as the SD, is the code that
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writes the attributes and data to a storage Volume (usually a tape or
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<DT><STRONG>Session</STRONG></DT>
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<DD><A NAME="221"></A>
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Normally refers to the internal conversation between the File daemon and
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the Storage daemon. The File daemon opens a <B>session</B> with the
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Storage daemon to save a FileSet, or to restore it. A session has a one
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to one correspondence to a Bacula Job (see above).
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<DT><STRONG>Verify</STRONG></DT>
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<DD><A NAME="223"></A>
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A verify is a job that compares the current file attributes to the
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attributes that have previously been stored in the Bacula Catalog. This
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feature can be used for detecting changes to critical system files
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similar to what <B>Tripwire</B> does. One of the major advantages of
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using Bacula to do this is that on the machine you want protected such
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as a server, you can run just the File daemon, and the Director, Storage
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daemon, and Catalog reside on a different machine. As a consequence, if
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your server is ever compromised, it is unlikely that your verification
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database will be tampered with.
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Verify can also be used to check that the most recent Job data written
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to a Volume agrees with what is stored in the Catalog (i.e. it compares
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the file attributes), *or it can check the Volume contents against the
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original files on disk.
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<DT><STRONG>*Archive</STRONG></DT>
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<DD><A NAME="225"></A>
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An Archive operation is done after a Save, and it consists of removing the
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Volumes on which data is saved from active use. These Volumes are marked as
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Archived, and may no longer be used to save files. All the files contained
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on an Archived Volume are removed from the Catalog. NOT YET IMPLEMENTED.
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<DT><STRONG>*Update</STRONG></DT>
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<DD><A NAME="226"></A>
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An Update operation causes the files on the remote system to be updated to be
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the same as the host system. This is equivalent to an <B>rdist</B> capability.
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<DT><STRONG>Retention Period</STRONG></DT>
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<DD><A NAME="228"></A>
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There are various kinds of retention periods that Bacula recognizes.
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The most important are the <B>File</B> Retention Period, <B>Job</B>
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Retention Period, and the <B>Volume</B> Retention Period. Each of these
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retention periods applies to the time that specific records will be kept
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in the Catalog database. This should not be confused with the time that
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the data saved to a Volume is valid.
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The File Retention Period determines the time that File records are kept
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in the catalog database. This period is important because the volume of
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the database File records by far use the most storage space in the
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database. As a consequence, you must ensure that regular "pruning" of
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the database file records is done. (See the Console <B>retention</B>
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command for more details on this subject).
609
The Job Retention Period is the length of time that Job records will be
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kept in the database. Note, all the File records are tied to the Job
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that saved those files. The File records can be purged leaving the Job
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records. In this case, information will be available about the jobs
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that ran, but not the details of the files that were backed up.
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Normally, when a Job record is purged, all its File records will also be
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The Volume Retention Period is the minimum of time that a Volume will be
619
kept before it is reused. Bacula will normally never overwrite a Volume
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that contains the only backup copy of a file. Under ideal conditions,
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the Catalog would retain entries for all files backed up for all current
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Volumes. Once a Volume is overwritten, the files that were backed up on
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that Volume are automatically removed from the Catalog. However, if
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there is a very large pool of Volumes or a Volume is never overwritten,
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the Catalog database may become enormous. To keep the Catalog to a
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manageable size, the backup information should be removed from the
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Catalog after the defined File Retention Period. Bacula provides the
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mechanisms for the catalog to be automatically pruned according to the
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retention periods defined.
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<DT><STRONG>Scan</STRONG></DT>
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<DD><A NAME="233"></A>
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A Scan operation causes the contents of a Volume or a series of Volumes
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to be scanned. These Volumes with the information on which files they
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contain are restored to the Bacula Catalog. Once the information is
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restored to the Catalog, the files contained on those Volumes may be
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easily restored. This function is particularly useful if certain
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Volumes or Jobs have exceeded their retention period and have been
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pruned or purged from the Catalog. Scanning data from Volumes into the
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Catalog is done by using the <B>bscan</B> program. See the <A HREF="Volume_Utility_Tools.html#bscan"> bscan
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section</A> of the Bacula Utilities Chapter of this manual for more
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<DT><STRONG>Volume</STRONG></DT>
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<DD><A NAME="237"></A>
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A Volume is an archive unit, normally a tape or a named disk file where
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Bacula stores the data from one or more backup jobs. All Bacula Volumes
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have a software label written to the Volume by Bacula so that it
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identifies what Volume it is really reading. (Normally there should be
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no confusion with disk files, but with tapes, it is easy to mount the
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<H2><A NAME="SECTION00047000000000000000">
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What Bacula is Not</A>
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<B>Bacula</B> is a backup, restore and verification program and is not a
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complete disaster recovery system in itself, but it can be a key part of one
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if you plan carefully and follow the instructions included in the
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<A HREF="Disast_Recove_Using_Bacula.html#_ChapterRescue"> Disaster Recovery</A> Chapter of this manual.
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With proper planning, as mentioned in the Disaster Recovery chapter <B>Bacula</B> can be a central component of your disaster recovery system. For
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example, if you have created an emergency boot disk, a Bacula Rescue disk to
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save the current partitioning information of your hard disk, and maintain a
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complete Bacula backup, it is possible to completely recover your system from
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"bare metal" that is starting from an empty disk.
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If you have used the <B>WriteBootstrap</B> record in your job or some other
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means to save a valid bootstrap file, you will be able to use it to extract
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the necessary files (without using the catalog or manually searching for the
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<H2><A NAME="SECTION00048000000000000000">
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Interactions Between the Bacula Services</A>
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The following block diagram shows the typical interactions between the Bacula
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Services for a backup job. Each block represents in general a separate process
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(normally a daemon). In general, the Director oversees the flow of
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information. It also maintains the Catalog.
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