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<?xml version="1.0" encoding="utf-8"?>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="generator" content=
"HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" />
<title>rsnapshot HOWTO</title>
<link href="http://www.xml-dev.com/blog/new.css" rel="stylesheet"
type="text/css" />
<meta content="DocBook XSL Stylesheets V1.64.1" name=
"generator" />
<meta name="description" content=
"rsnapshot is a filesystem backup utility based on rsync. Using rsnapshot, it is possible to take snapshots of your filesystems at different points in time. Using hard links, rsnapshot creates the illusion of multiple full backups, while only taking up the space of one full backup plus differences. When coupled with ssh, it is possible to take snapshots of remote filesystems as well. This document is a tutorial in the installation and configuration of rsnapshot." />
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</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084"
alink="#0000FF">
<div class="article" lang="en">
<div class="titlepage">
<div>
<div>
<h1 class="title"><a name="N10001"></a>rsnapshot
HOWTO</h1>
</div>
<div>
<div class="author">
<h3 class="author"><span class=
"firstname">David</span> <span class=
"surname">Cantrell</span></h3>
<div class="affiliation">
<div class="address">
<p><span style="white-space: pre;"><tt class=
"email"><<a href=
</div>
</div>
</div>
</div>
<div>
<p class="pubdate">2004-01-20</p>
</div>
<!--<div>
<div class="revhistory">
<table summary="Revision history" width="100%" border=
"1">
<tr>
<th colspan="3" valign="top" align="left">
<b>Revision History</b></th>
</tr>
<tr>
<td align="left">Revision 1.2</td>
<td align="left">2006-10-06</td>
<td align="left">DC</td>
</tr>
<tr>
<td colspan="3" align="left">Clarified that prev.max is renamed to create the next level of backup;<br>changed most refs to Nathan to say David instead.</td>
</tr>
<tr>
<td align="left">Revision 1.0.0</td>
<td align="left">2005-01-31</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Updated for rsnapshot
1.2.0</td>
</tr>
<tr>
<td align="left">Revision 0.9.7</td>
<td align="left">2005-01-17</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Spelling corrections
submitted by Nicolas Kaiser</td>
</tr>
<tr>
<td align="left">Revision 0.9.6</td>
<td align="left">2004-12-13</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Misc. updates</td>
</tr>
<tr>
<td align="left">Revision 0.9.5</td>
<td align="left">2004-07-10</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Relicensed document
under GPL, instead of FDL</td>
</tr>
<tr>
<td align="left">Revision 0.9.4</td>
<td align="left">2004-07-02</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Added description of
proper crontab time settings</td>
</tr>
<tr>
<td align="left">Revision 0.9.3</td>
<td align="left">2004-06-11</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Misc. updates</td>
</tr>
<tr>
<td align="left">Revision 0.9.2</td>
<td align="left">2004-05-16</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Updated --link-dest
info</td>
</tr>
<tr>
<td align="left">Revision 0.9.1</td>
<td align="left">2004-01-20</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">Added --link-dest
info</td>
</tr>
<tr>
<td align="left">Revision 0.9</td>
<td align="left">2004-01-10</td>
<td align="left">NR</td>
</tr>
<tr>
<td colspan="3" align="left">First draft</td>
</tr>
</table>
</div>
</div>-->
<div>
<div class="abstract">
<p class="title"><b>Abstract</b></p>
<p>rsnapshot is a filesystem backup utility based on
rsync. Using rsnapshot, it is possible to take
snapshots of your filesystems at different points in
time. Using hard links, rsnapshot creates the illusion
of multiple full backups, while only taking up the
space of one full backup plus differences. When coupled
with ssh, it is possible to take snapshots of remote
filesystems as well. This document is a tutorial in the
installation and configuration of rsnapshot.</p>
</div>
</div>
</div>
<hr />
</div>
<div class="toc">
<p><b>Table of Contents</b></p>
<dl>
<dt><span class="sect1"><a href="#intro">1.
Introduction</a></span></dt>
<dd>
<dl>
<dt><span class="sect2"><a href=
"#what_you_will_need">1.1. What you will
need</a></span></dt>
<dt><span class="sect2"><a href="#copyright">1.2.
Copyright and License</a></span></dt>
<dt><span class="sect2"><a href="#disclaimer">1.3.
Disclaimer</a></span></dt>
<dt><span class="sect2"><a href="#feedback">1.4.
Feedback</a></span></dt>
</dl>
</dd>
<dt><span class="sect1"><a href="#motivation">2.
Motivation</a></span></dt>
<dt><span class="sect1"><a href="#installation">3.
Installation</a></span></dt>
<dd>
<dl>
<dt><span class="sect2"><a href=
"#thirty_second_version">3.1. 30 second version (for
the impatient)</a></span></dt>
<dt><span class="sect2"><a href=
"#untar_the_source_code_package">3.2. Untar the source
code package</a></span></dt>
<dt><span class="sect2"><a href=
"#change_to_src_dir">3.3. Change to the source
directory</a></span></dt>
<dt><span class="sect2"><a href=
"#decide_where_to_install">3.4. Decide where you want
to install</a></span></dt>
<dt><span class="sect2"><a href=
"#run_the_configure_script">3.5. Run the configure
script</a></span></dt>
<dt><span class="sect2"><a href=
"#install_the_program">3.6. Install the
program</a></span></dt>
</dl>
</dd>
<dt><span class="sect1"><a href="#configuration">4.
Configuration</a></span></dt>
<dd>
<dl>
<dt><span class="sect2"><a href=
"#create_the_config_file">4.1. Create the config
file</a></span></dt>
<dt><span class="sect2"><a href=
"#where_to_go_for_more_info">4.2. Where to go for more
info</a></span></dt>
<dt><span class="sect2"><a href=
"#modifying_the_config_file">4.3. Modifying the config
file</a></span></dt>
<dt><span class="sect2"><a href=
"#testing_your_config_file">4.4. Testing your config
file</a></span></dt>
</dl>
</dd>
<dt><span class="sect1"><a href="#automation">5.
Automation</a></span></dt>
<dt><span class="sect1"><a href="#how_it_works">6. How it
works</a></span></dt>
<dt><span class="sect1"><a href="#restoring_backups">7.
Restoring backups</a></span></dt>
<dd>
<dl>
<dt><span class="sect2"><a href="#root_only">7.1. root
only</a></span></dt>
<dt><span class="sect2"><a href="#all_users">7.2. All
users</a></span></dt>
</dl>
</dd>
<dt><span class="sect1"><a href="#conclusion">8.
Conclusion</a></span></dt>
<dt><span class="sect1"><a href="#more_resources">9. More
resources</a></span></dt>
</dl>
</div>
<div class="sect1" lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a name=
"intro"></a>1. Introduction</h2>
</div>
</div>
</div>
<p>rsnapshot is a filesystem backup utility based on rsync.
Using rsnapshot, it is possible to take snapshots of your
filesystems at different points in time. Using hard links,
rsnapshot creates the illusion of multiple full backups,
while only taking up the space of one full backup plus
differences. When coupled with ssh, it is possible to take
snapshots of remote filesystems as well.</p>
<p>rsnapshot is written in Perl, and depends on rsync.
OpenSSH, GNU cp, GNU du, and the BSD logger program are also
recommended, but not required. All of these should be present
on most Linux systems. rsnapshot is written with the lowest
common denominator in mind. It only requires at minimum Perl
5.004 and rsync. As a result of this, it works on pretty much
any UNIX-like system you care to throw at it. It has been
successfully tested with Perl 5.004 through 5.8.2, on Debian,
Redhat, Fedora, Solaris, Mac OS X, FreeBSD, OpenBSD, NetBSD,
and IRIX.</p>
<p>The latest version of the program and this document can
always be found at <a href="http://www.rsnapshot.org/"
target="_top">http://www.rsnapshot.org/</a>.</p>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"what_you_will_need"></a>1.1. What you
will need</h3>
</div>
</div>
</div>
<p>At a minimum: <i class="emphasis">perl, rsync</i></p>
<p>Optionally: <i class="emphasis">ssh, logger, GNU cp, GNU
du</i></p>
<p>Additionally, it will help if you have reasonably good
sysadmin skills.</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"copyright"></a>1.2. Copyright and
License</h3>
</div>
</div>
</div>
<p>This document, rsnapshot HOWTO, is copyrighted (c) 2005
by Nathan Rosenquist, with some portions (c) 2006 David
Cantrell. You can redistribute it and/or modify
it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version. A
copy of the license is available at <a href=
"http://www.gnu.org/copyleft/gpl.html" target=
"_top">http://www.gnu.org/copyleft/gpl.html</a>.</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"disclaimer"></a>1.3. Disclaimer</h3>
</div>
</div>
</div>
<p>No liability for the contents of this document can be
accepted. Use the concepts, examples and information at
your own risk. There may be errors and inaccuracies, that
could be damaging to your system. Proceed with caution, and
although this is highly unlikely, the author(s) do not take
any responsibility.</p>
<p>All copyrights are held by their by their respective
owners, unless specifically noted otherwise. Use of a term
in this document should not be regarded as affecting the
validity of any trademark or service mark. Naming of
particular products or brands should not be seen as
endorsements.</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"feedback"></a>1.4. Feedback</h3>
</div>
</div>
</div>
<p>Feedback is most certainly welcome for this document.
Send your additions, comments and criticisms to the
following email address : <tt class="email"><<a href=
</div>
</div>
<div class="sect1" lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a name=
"motivation"></a>2. Motivation</h2>
</div>
</div>
</div>
<p>I originally used Mike Rubel's shell scripts to do rsync
snapshots a while back. These worked very well, but there
were a number of things that I wanted to improve upon. I had
to write two shell scripts that were customized for my
server. If I wanted to change the number of intervals stored,
or the parts of the filesystem that were archived, that meant
manually editing these shell scripts. If I wanted to install
them on a different server with a different configuration,
this meant manually editing the scripts for the new server,
and hoping the logic and the sequence of operations was
correct. Also, I was doing all the backups locally, on a
single machine, on a single hard drive (just to protect from
dumb user mistakes like deleting files). Never the less, I
continued on with this system for a while, and it did work
very well.</p>
<p>Several months later, the IDE controller on my web server
failed horribly (when I typed <span><b class=
"command">/sbin/shutdown</b></span>, it said the command was
not found). I was then faced with what was in the back of my
mind all along: I had not been making regular remote backups
of my server, and the local backups were of no use to me
since the entire drive was corrupted. The reason I had only
been making sporadic, partial remote backups is that they
weren't automatic and effortless. Of course, this was no
one's fault but my own, but I got frustrated enough to write
a tool that would make automated remote snapshots so easy
that I wouldn't ever have to worry about them again. This
goal has long been reached, but work on rsnapshot still
continues as people submit patches, request features, and
ways are found to improve the program.</p>
</div>
<div class="sect1" lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a name=
"installation"></a>3. Installation</h2>
</div>
</div>
</div>
<p>This section will walk you through the installation of
rsnapshot, step by step. This is not the only way to do it,
but it is a way that works and that is well documented. Feel
free to improvise if you know what you're doing.</p>
<p>This guide assumes you are installing rsnapshot 1.2.0 for
the first time. If you are upgrading from an earlier version,
please read the <tt class="filename">INSTALL</tt> file that
comes with the source distribution instead.</p>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"thirty_second_version"></a>3.1. 30 second
version (for the impatient)</h3>
</div>
</div>
</div>
<pre class="screen">
<span><b class="command">./configure --sysconfdir=/etc</b></span>
<span><b class="command">su</b></span>
<span><b class="command">make install</b></span>
<span><b class=
"command">cp /etc/rsnapshot.conf.default /etc/rsnapshot.conf</b></span>
</pre>
<p>The rest of this section is the long version.</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"untar_the_source_code_package"></a>3.2. Untar
the source code package</h3>
</div>
</div>
</div>
<pre class="screen">
<span><b class="command">tar xzvf rsnapshot-1.2.0.tar.gz</b></span>
</pre>
<p>If you don't have GNU <tt class="filename">tar</tt>, you
may have to do this in two steps instead:</p>
<pre class="screen">
<span><b class="command">gunzip rsnapshot-1.2.0.tar.gz</b></span>
<span><b class="command">tar xvf rsnapshot-1.2.0.tar</b></span>
</pre>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"change_to_src_dir"></a>3.3. Change to the
source directory</h3>
</div>
</div>
</div>
<pre class="screen">
<span><b class="command">cd rsnapshot-1.2.0/</b></span>
</pre>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"decide_where_to_install"></a>3.4. Decide
where you want to install</h3>
</div>
</div>
</div>
<p>By default, the installation procedure will install all
files under <tt class="filename">/usr/local</tt>. For this
tutorial, this will be OK except we will install the config
file under <tt class="filename">/etc</tt>.</p>
<p>We are assuming that <tt class="filename">rsync</tt>,
<tt class="filename">ssh</tt>, <tt class=
"filename">logger</tt>, and <tt class="filename">du</tt>
are all in your search path. If this is not the case, you
can specify the path to any of these programs using the
typical Autoconf <i class=
"parameter"><tt>--with-program=/path/to/program</tt></i>
syntax. For example, if Perl was in <tt class=
"filename">/opt/bin/perl</tt> and rsync was in <tt class=
"filename">/home/me/bin/rsync</tt>, you could run configure
like:</p>
<pre class="screen">
<span><b class=
"command">./configure --with-perl=/opt/bin/perl --with-rsync=/home/me/bin/rsync</b></span>
</pre>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"run_the_configure_script"></a>3.5. Run
the configure script</h3>
</div>
</div>
</div>
<p>This will poke and prod your system to figure out where
the various external programs that rsnapshot depends on
live. It also generates the Makefile that we will use to
install the program. The configure script accepts arguments
that can be used to tell it where to install the program,
and also where to find the supporting programs. For this
installation, the only non-default option we want is to put
the config file in the <tt class="filename">/etc</tt>
directory. To do this, run this command at the shell:</p>
<pre class="screen">
<span><b class="command">./configure --sysconfdir=/etc</b></span>
</pre>
<p>If all goes well, you're ready to install the program.
If there was a problem, it should be descriptive. Most
likely a problem would be the result of something that was
required and not found (like rsync or perl). If this
happens, you must figure out where the missing program is
located on your system, or install it if necessary. If you
know where it is but configure couldn't find it, you can
specify the path using the <i class=
"parameter"><tt>--with-program=/path/to/program</tt></i>
options described above.</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"install_the_program"></a>3.6. Install the
program</h3>
</div>
</div>
</div>
<p>If you've followed these instructions so far, you will
have configured rsnapshot to be installed under <tt class=
"filename">/usr/local</tt>, with the config file in
<tt class="filename">/etc</tt>. Under these circumstances,
it will be necessary to become root to install the program.
Now is the time to do so. You will, of course, need the
root password to do this:</p>
<pre class="screen">
<span><b class="command">su</b></span>
</pre>
<p>This will prompt you for the root password.</p>
<p>Now, to install rsnapshot, run the following
command:</p>
<pre class="screen">
<span><b class="command">make install</b></span>
</pre>
<p>This will install rsnapshot with all the settings you
specified in the ./configure stage. If all goes well, you
will have the following files on your system:</p>
<p><tt class="filename">/usr/local/bin/rsnapshot</tt> The
rsnapshot program</p>
<p><tt class=
"filename">/usr/local/man/man1/rsnapshot.1</tt> Man
page</p>
<p><tt class="filename">/etc/rsnapshot.conf.default</tt>
The example config file</p>
<p>If you decide later that you don't want rsnapshot on
your system anymore, simply remove the files listed above,
or run <span><b class="command">make uninstall</b></span>
in the same source directory you installed from. Of course,
if you installed with different options, the location of
these files may be different.</p>
</div>
</div>
<div class="sect1" lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a name=
"configuration"></a>4. Configuration</h2>
</div>
</div>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"create_the_config_file"></a>4.1. Create
the config file</h3>
</div>
</div>
</div>
<p>In the install process, the config file is not created
or installed. However, a working example is provided that
you can copy. To copy the example config file into the
location rsnapshot will be looking for the real config
file:</p>
<pre class="screen">
<span><b class=
"command">cp /etc/rsnapshot.conf.default /etc/rsnapshot.conf</b></span>
</pre>
<p>As a general rule, you should avoid modifying <tt class=
"filename">/etc/rsnapshot.conf.default</tt>, simply because
it is a working example that you may wish to refer to
later. Also, if you perform an upgrade, the <tt class=
"filename">rsnapshot.conf.default</tt> file will always be
upgraded to the latest version, while your real config file
will be safe out of harm's way. Please note that if you run
<span><b class="command">make upgrade</b></span> during an
upgrade, your rsnapshot.conf may be modified slightly, and
the original will then be saved in <tt class=
"filename">rsnapshot.conf.backup</tt> in the same
directory.</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"where_to_go_for_more_info"></a>4.2. Where
to go for more info</h3>
</div>
</div>
</div>
<p>The <tt class="filename">rsnapshot.conf</tt> config file
is well commented, and much of it should be fairly
self-explanatory. For a full reference of all the various
options, please consult the rsnapshot man page. Type:</p>
<pre class="screen">
<span><b class="command">man rsnapshot</b></span>
</pre>
<p>This will give you the complete documentation. However,
it assumes that you already know what you're doing to a
certain extent. If you just want to get something up and
running, this tutorial is a better place to start. If your
system can't find the man page, <tt class=
"filename">/usr/local/man</tt> probably isn't in your
$MANPATH environmental variable. This is beyond the scope
of this document, but if it isn't working for you, you can
always read the newest man page on the rsnapshot web site
at <a href="http://www.rsnapshot.org/" target=
"_top">http://www.rsnapshot.org/</a></p>
</div>
<div class="sect2" lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a name=
"modifying_the_config_file"></a>4.3. Modifying
the config file</h3>
</div>
</div>
</div>
<p>In this example, we will be using the <tt class=
"filename">/.snapshots/</tt> directory to hold the
filesystem snapshots. This is referred to as the
<span class="quote">snapshot
root</span>. Feel free to put this anywhere
you have lots of free disk space. However, the examples in
this document assume you have not changed this parameter,
so you will have to substitute this in your commands if you
put it somewhere else.</p>
<p>Also please note that fields are separated by tabs, not
spaces. The reason for this is so it's easier to specify
file paths with spaces in them.</p>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"cmd_cp"></a>4.3.1. cmd_cp</h4>
</div>
</div>
</div>
<p>If enabled, the <i class="emphasis">cmd_cp</i>
parameter should contain the path to the GNU <tt class=
"filename">cp</tt> program on your filesystem. If you are
using Linux, be sure to uncomment this by removing the
hash mark (#) in front of it. If you are using BSD,
Solaris, IRIX, or most other UNIX variants, you should
leave this commented out.</p>
<p>What makes GNU <tt class="filename">cp</tt> so special
is that unlike the traditional UNIX <tt class=
"filename">cp</tt>, it has the ability to make recursive
<span class=
"quote">copies</span> of directories as hard
links.</p>
<p>If you don't have GNU <tt class="filename">cp</tt>,
there is a subroutine in rsnapshot that somewhat
approximates this functionality (although it won't
support more esoteric files such as device nodes, FIFOs,
sockets, etc). This gets followed up by another call to
rsync, which transfers the remaining special files, if
any. In this way, rsnapshot can support all file types on
every platform.</p>
<p>The rule of thumb is that if you're on a Linux system,
leave <i class="emphasis">cmd_cp</i> enabled. If you
aren't on a Linux system, leave <i class=
"emphasis">cmd_cp</i> disabled. There are reports of GNU
<tt class="filename">cp</tt> working on BSD and other
non-Linux platforms, but there have also been some cases
where problems have been encountered. If you enable
<i class="emphasis">cmd_cp</i> on a non-Linux platform,
please let the mailing list know how it worked out for
you.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"cmd_rsync"></a>4.3.2. cmd_rsync</h4>
</div>
</div>
</div>
<p>The <i class="emphasis">cmd_rsync</i> parameter must
not be commented out, and it must point to a working
version of <tt class="filename">rsync</tt>. If it
doesn't, the program just will not work at all.</p>
<p>Please note that if you are using IRIX, there is
another program named <tt class="filename">rsync</tt>
that is different than the
<span class="quote">real</span>
<tt class="filename">rsync</tt> most people know of. If
you're on an IRIX machine, you should double check
this.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"cmd_ssh"></a>4.3.3. cmd_ssh</h4>
</div>
</div>
</div>
<p>If you have <tt class="filename">ssh</tt> installed on
your system, you will want to uncomment the <i class=
"emphasis">cmd_ssh</i> parameter. By enabling <tt class=
"filename">ssh</tt>, you can take snapshots of any number
of remote systems. If you don't have <tt class=
"filename">ssh</tt>, or plan to only take snapshots of
the local filesystem, you may safely leave this commented
out.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"cmd_logger"></a>4.3.4. cmd_logger</h4>
</div>
</div>
</div>
<p>The <i class="emphasis">cmd_logger</i> parameter
specifies the path to the <tt class=
"filename">logger</tt> program. <tt class=
"filename">logger</tt> is a command line interface to
syslog. See the <tt class="filename">logger</tt> man page
for more details. <tt class="filename">logger</tt> should
be a standard part of most UNIX-like systems. It appears
to have remained unchanged since about 1993, which is
good for cross-platform stability. If you comment out
this parameter, it will disable syslog support in
rsnapshot. It is recommended that you leave this
enabled.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"cmd_du"></a>4.3.5. cmd_du</h4>
</div>
</div>
</div>
<p>The <i class="emphasis">cmd_du</i> parameter specifies
the path to the <tt class="filename">du</tt> program.
<tt class="filename">du</tt> is a command line tool that
reports on disk usage. rsnapshot uses <tt class=
"filename">du</tt> to generate reports about the actual
amount of disk space taken up, which is otherwise
difficult to estimate because of all the hard links.</p>
<p>If you comment this out, rsnapshot will try to use the
version of <tt class="filename">du</tt> it finds in your
path, if possible. The GNU version of <tt class=
"filename">du</tt> is recommended, since it has the best
selection of features, and supports the most options. The
BSD version also seems to work, although it doesn't
support the <span><b class="command">-h</b></span> flag.
Solaris <span><b class="command">du</b></span> does not
work at all, because it doesn't support the
<span><b class="command">-c</b></span> parameter.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"link_dest"></a>4.3.6. link_dest</h4>
</div>
</div>
</div>
<p>If you have <tt class="filename">rsync</tt> version
2.5.7 or later, you may want to enable this. With
<i class="emphasis">link_dest</i> enabled, rsnapshot
relies on rsync to create recursive hard links,
overriding GNU cp in most, but not all, cases. With
<i class="emphasis">link_dest</i> enabled, every single
file on your system can be backed up in one pass, on any
operating system. To get the most out of rsnapshot on
non-Linux platforms, <i class="emphasis">link_dest</i>
should be enabled. Be advised, however, that if a remote
host is unavailable during a backup, rsnapshot will take
an extra step and roll back the files from the previous
backup. Using GNU cp, this would not be necessary.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"retain"></a>4.3.7. retain</h4>
</div>
</div>
</div>
<p>rsnapshot has no idea how often you want to take
snapshots. Everyone's backup scheme may be different. In
order to specify how much data to save, you need to tell
rsnapshot which backups
to keep, and how
many of each. A backup, in the context of the
rsnapshot config file, is just a name.
These can actually be named anything (as long as it's
alphanumeric, and not a reserved word), but a very common
convention is to use names like <i class="emphasis">hourly</i> and
<i class="emphasis">daily</i> and so on. In this example, we want
to take a snapshot every four hours, or six times a day
(these are the <i class="emphasis">hourly</i> backups).
We also want to keep a second set, which are taken once a
day, and stored for a week (or seven days). The relevant
section of the config file would, in this case, look like:</p>
<pre class="screen">
retain hourly 6
retain daily 7
</pre>
<p>We use the <span class="quote">retain</span>
keyword to describe how many of which level of backup to keep.
<span class="quote">interval</span>
is a deprecated synonym.
<p>It also has some other entries, but you can either
ignore them or comment them out for now.</p>
<p>Please note that the <i class="emphasis">hourly</i>
backup is specified first. This is very important. The
first <i class="emphasis">retain</i> line is assumed to
be the smallest unit of time, with each additional line
getting successively larger. Thus, if you add a <i class=
"emphasis">yearly</i> backup, it should go at the
bottom, and if you add a <i class="emphasis">minutes</i>
backup, it should go before hourly. It's also worth
noting that the snapshots get
<span class="quote">promoted</span>
from the most first-mentioned to the
later ones in sequence. In this example, the daily snapshots get pulled
from the oldest hourly snapshot, not directly from the
main filesystem.</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"backup"></a>4.3.8. backup</h4>
</div>
</div>
</div>
<p>Please note that the destination paths specified here
are based on the assumption that the <i class=
"emphasis">--relative</i> flag is being passed to
<tt class="filename">rsync</tt> via the <i class=
"emphasis">rsync_long_args</i> parameter. If you are
installing for the first time, this is the default
setting. If you upgraded from a previous version, please
read the <tt class="filename">INSTALL</tt> file that came
with the source distribution for more information.</p>
<p>This is the section where you tell rsnapshot what
files you actually want to back up. You put a
<span class=
"quote">backup</span> parameter first,
followed by the full path to the directory or network
path you're backing up. The third column is the relative
path you want to back up to inside the snapshot root.
Let's look at an example:</p>
<pre class="screen">
backup /etc/ localhost/
</pre>
<p>In this example, <i class="emphasis">backup</i> tells
us it's a backup point. <tt class="filename">/etc/</tt>
is the full path to the directory we want to take
snapshots of, and <tt class="filename">localhost/</tt> is
a directory inside the <i class=
"emphasis">snapshot_root</i> we're going to put them in.
Using the word <i class="emphasis">localhost</i> as the
destination directory is just a convention. You might
also choose to use the server's fully qualified domain
name instead of <i class="emphasis">localhost</i>. If you
are taking snapshots of several machines on one dedicated
backup server, it's a good idea to use their various
hostnames as directories to keep track of which files
came from which server.</p>
<p>In addition to full paths on the local filesystem, you
can also backup remote systems using <tt class=
"filename">rsync</tt> over <tt class="filename">ssh</tt>.
If you have <tt class="filename">ssh</tt> installed and
enabled (via the <i class="emphasis">cmd_ssh</i>
parameter), you can specify a path like:</p>
<pre class="screen">
backup [email protected]:/etc/ example.com/
</pre>
<p>This behaves fundamentally the same way, but you must
take a few extra things into account.</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>The ssh daemon must be running on
example.com</p>
</li>
<li>
<p>You must have access to the account you specify
the remote machine, in this case the root user on
example.com.</p>
</li>
<li>
<p>You must have key-based logins enabled for the
root user at example.com, without passphrases. If
you wanted to perform backups as another user, you
could specify the other user instead of root for
the source (i.e. [email protected]). Please note that
allowing remote logins with no passphrase is a
security risk that may or may not be acceptable in
your situation. Make sure you guard access to the
backup server very carefully! For more information
on how to set this up, please consult the ssh man
page, or a tutorial on using ssh public and private
keys. You will find that the key based logins are
better in many ways, not just for rsnapshot but for
convenience and security in general. One thing you
can do to mitigate the potential damage from a
backup server breach is to create alternate users
on the client machines with uid and gid set to 0,
but with a more restrictive shell such as
scponly.</p>
</li>
<li>
<p>This backup occurs over the network, so it may
be slower. Since this uses <tt class=
"filename">rsync</tt>, this is most noticeable
during the first backup. Depending on how much your
data changes, subsequent backups should go much,
much faster since <i class="emphasis">rsync</i>
only sends the differences between files.</p>
</li>
</ul>
</div>
</div>
<div class="sect3" lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a name=
"backup_script"></a>4.3.9. backup_script</h4>
</div>
</div>
</div>
<p>With this parameter, the second column is the full
path to an executable backup script, and the third column
is the local path you want to store it in (just like with
the "backup" parameter). For example:</p>
<pre class="screen">
backup_script /usr/local/bin/backup_pgsql.sh localhost/postgres/
</pre>
<p>In this example, rsnapshot will run the script
<tt class="filename">/usr/local/bin/backup_pgsql.sh</tt>
in a temp directory, then sync the results into the
<tt class="filename">localhost/postgres/</tt> directory
under the snapshot root. You can find the backup_pgsql.sh
example script in the <tt class="filename">utils/</tt>
directory of the source distribution. Feel free to modify
it for your system.</p>
<p>Your backup script simply needs to dump out the
contents of whatever it does into its current working
directory. It can create as many files and/or directories
as necessary, but it should not put its files in any
pre-determined path. The reason for this is that
rsnapshot creates a temp directory, changes to that
directory, runs the backup script, and then syncs the
contents of the temp directory to the local path you
specified in the third column. A typical backup script
would be one that archives the contents of a database. It
might look like this:</p>
<pre class="screen">
<span><b class="command">#!/bin/sh
/usr/bin/mysqldump -uroot mydatabase > mydatabase.sql
/bin/chmod 644 mydatabase.sql</b></span>
</pre>
<p>There are several example scripts in the <tt class=
"filename">utils/</tt> directory of the rsnapshot source
distribution to give you more ideas.</p>
<p>Make sure the destination path you specify is unique.
The backup script will completely overwrite anything in
the destination path, so if you tried to specify the same
destination twice, you would be left with only the files