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<h1>pdumpfs: a daily backup system similar to Plan9's dumpfs</h1>
<p>Last Modified: 2002-08-06</p>
<hr>

<h2>What's pdumpfs?</h2>

<p>
pdumpfs is a simple daily backup system similar to Plan9's
dumpfs which preserves every daily snapshot. pdumpfs is
written in <a href="http://www.ruby-lang.org/">Ruby</a>.
You can access the past snapshots at any time for retrieving
a certain day's file.  Let's backup your home directory with
pdumpfs!
</p>

<p>
pdumpfs constructs the snapshot YYYY/MM/DD in the
destination directory. All source files are copied to
the snapshot directory for the first time. On and after
the second time, pdumpfs copies only updated or newly
created files and stores unchanged files as hard links
to the files of the previous day's snapshot for saving a
disk space.
</p>

<p>
Tha latest version of pdumpfs is available at 
<a href="http://namazu.org/~satoru/pdumpfs/">
http://namazu.org/~satoru/pdumpfs/</a>.
</p>

<h2><a name="news">What's New</a></h2>

<ul>
<li><strong>2002-08-06</strong>: <a
href="#download">pdumpfs 0.6</a> Released!<br>

<ul>
<li>Be resistant to files disappearing while it runs.
</ul>


<li><strong>2001-02-19</strong>: <a
href="#download">pdumpfs 0.1</a> Released!<br>

</ul>

<h2>Usage</h2>

<h3>Setting</h3>

<p>
Edit the first line of pdumpfs: <code>#!
/usr/local/bin/ruby</code> if necessary.
</p>

<h3>Command Line</h3>

<pre>
   % pdumpfs &lt;source directory&gt; &lt;destination directory&gt;
</pre>

<h3>Example</h3>

<p>
To backup your home directory /home/yourname to /backup, run
the following command.
</p>

<pre>
   % pdumpfs /home/yourname /backup &gt;/backup/log 2&gt;/backup/error-log
</pre>

<p>

On and after the second day, it is a good idea to invoke the
backup command with cron daemon.  The following setting
allows you to backup your home directory every 5 a.m.
</p>

<pre>
    00 05 * * * pdumpfs /home/yourname /backup &gt;/backup/log 2&gt;/backup/error-log
</pre>

<p>
If the backup system works well, you can retrieve a certain
day's file with a file name like /backup/2001/02/19/yourname/...
</p>

<h2>Limitation</h2>

<ul>
<li>pdumpfs can handle only normal files, directories, and
symbolic links.

<li>pdumpfs may not work on systems other than UNIX because
pdumpfs utilizes hard links.

<li>pdumpfs is not suited for a directory containing large
files which update frequently. 

<li>If more than 31 days absence occurs, incremental backup
would not be performed. So, backup your files everyday.

<li>With pdumpfs, you can easily remove unnecessary files
because the past files can be retrieved at any
time. However, please do not put too much confidence in
pdumpfs.  pdumpfs may have serious bugs.


</ul>



<h2>Tips</h2>

<ul>
<li>If files are increased by 10 MB everyday, about 4 GB
disk space is consumed by one year. It is not too much,
considering the recent evolution of computer resources.


<li>Backup your files to a physically separated device.

<li>With a linux ext2/ext3 filesystem, 
files can be immutable with chattr command.
To make all files in /backup immutable, run <code>chattr -R
+i /backup</code> with the root privilege. chattr command
keep you from doing rm -rf backup files by accident.
</ul>

<h2><a name="download">Download</a></h2>

<p>
pdumpfs is a free software with ABSOLUTELY NO WARRANTY under
the terms of the <a
href="http://www.gnu.org/copyleft/gpl.html">GNU General
Public License version 2</a>.

</p>

<ul>
<li><a href="pdumpfs-0.6.tar.gz">pdumpfs-0.6.tar.gz</a>
(about 8 KB)
<li><a href="http://cvs.namazu.org/pdumpfs/">CVS</a>
</ul>


<hr>
<p>
$Id: pdumpfs-en.html,v 1.13 2002/08/06 08:46:03 satoru Exp $
</p>
<address><a href="http://namazu.org/~satoru/">Satoru Takabayashi</a> (satoru@namazu.org)</address>