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<h2 class="title" style="clear: both"><a id="recover"></a>Recovering from a Backup</h2>
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<dl>
<dt>
<span class="sect2">
<a href="recover.html#catastrophicrecovery">Catastrophic Recovery</a>
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<p>
If you used standard Berkeley DB backup procedures to backup your
database, then you can restore your database using the
procedures described in this section.
</p>
<p>
Note that Berkeley DB supports two types of recovery:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
Normal recovery, which examines only those
log records needed to bring the database to a consistent
state since the last checkpoint. Normal recovery
starts with any logs used by any transactions active at
the time of the last checkpoint, and examines all logs
from then to the current logs.
</p>
<p>
Normal recovery is automatically run (if necessary) when you open
your database. It is necessary to run recovery if a
thread or process shuts down without properly closing
the database.
</p>
</li>
<li>
<p>
Catastrophic recovery examines all available log files.
You use catastrophic recovery to restore your database
from a previously created backup.
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<h3 class="title"><a id="catastrophicrecovery"></a>Catastrophic Recovery</h3>
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<p>
Use catastrophic recovery when you are
recovering your database from a previously created backup.
Note that to restore your database from a previous backup, you
should copy the backup to a new environment directory, and
then run catastrophic recovery. Failure to do so can lead to
the internal database structures being out of sync with your log files.
</p>
<p>
To run catastrophic recovery:
</p>
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<ul type="disc">
<li>
<p>
Shutdown all database operations.
</p>
</li>
<li>
<p>
Restore the backup to an empty directory. This means
you need your database file, as well as the
<code class="literal">-journal</code> directory, and any
available log files that the backup contains.
</p>
<p>
Note that the backup database file and the journal
directory must have the same name as the database
and journal directory that you are restoring.
You can put the backup in a different location
on disk, but the name of the file and directory
must remain the same.
</p>
</li>
<li>
<p>
Make sure that a <code class="literal">DB_CONFIG</code>
file exists in the journal directory that you
are using to restore your database. This file
must contain a the following line:
</p>
<pre class="programlisting">set_data_dir ..</pre>
</li>
<li>
<p>
Run the <a href="../api_reference/C/db_recover.html" class="olink">db_recover</a> command line
utility with the <code class="literal">-c</code> option.
</p>
</li>
</ul>
</div>
<p>
Note that catastrophic recovery examines every available
log file — not just those log files created since the
last checkpoint as is the case for normal recovery. For this reason,
catastrophic recovery is likely to take longer than does
normal recovery.
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