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<span xmlns="http://www.w3.org/1999/xhtml">DbEnv::backup()</span>
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The DbEnv Handle
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<div class="sect1" lang="en" xml:lang="en">
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<h2 class="title" style="clear: both"><a id="envbackup"></a>
<span>DbEnv::backup()</span>
</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::backup(const char *target, u_int32_t flags);</pre>
<p>
The <code class="methodname">DbEnv::backup()</code> method performs a hot
backup of the open environment. All files used by the environment
are backed up, so long as the normal rules for file placement are
followed. For information on how files are normally placed relative
to the environment directory, see
<a href="../../programmer_reference/env_naming.html" class="olink">Berkeley DB File Naming</a> in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
</p>
<p>
By default, data directories and the log directory specified
relative to the home directory will be recreated relative to the
target directory. If absolute path names are used, then specify
<code class="literal">DB_BACKUP_SINGLE_DIR</code> to the <code class="literal">flags</code>
parameter.
</p>
<p>
This method provides the same functionality as the
<a class="xref" href="db_hotbackup.html" title="db_hotbackup">db_hotbackup</a>
utility. However, this method does not perform the housekeeping
actions performed by the <code class="literal">db_hotbackup</code> utility.
In particular, you may want to run a checkpoint before calling this
method. To run a checkpoint, use the
<a class="xref" href="txncheckpoint.html" title="DbEnv::txn_checkpoint()">
<span>DbEnv::txn_checkpoint()</span>
</a>
method. For more information on checkpoints, see
<a href="../../programmer_reference/transapp_checkpoint.html" class="olink">Checkpoints</a> in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
</p>
<p>
To back up a single database file contained within the environment,
use the
<a class="xref" href="envdbbackup.html" title="DbEnv::dbbackup()">
<span>DbEnv::dbbackup()</span>
</a>
method.
</p>
<p>
This method's default behavior can be changed by setting backup
callbacks. See
<a class="xref" href="envset_backup_callbacks.html" title="DbEnv::set_backup_callbacks()">
<span>DbEnv::set_backup_callbacks()</span>
</a>
for more information. Additional tuning parameters can also be set
using the
<a class="xref" href="envset_backup_config.html" title="DbEnv::set_backup_config()">
<span>DbEnv::set_backup_config()</span>
</a> method.
</p>
<p>
The <code class="methodname">DbEnv::backup()</code> method may only be
called after the environment handle has been opened.
</p>
<p>
The <code class="methodname">DbEnv::backup()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755616482720"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755616481568"></a>target</h4>
</div>
</div>
</div>
<p>
Identifies the directory in which the back up will be
placed. Any subdirectories required to contain the backup
must be placed relative to this directory. Note that if
the backup callbacks are set, then the value specified to
this parameter is passed on to the <code class="literal">open_func()</code>
callback. If this parameter is NULL, then the target must
be specified to the <code class="literal">open_func()</code>
callback.
</p>
<p>
This directory, and any required subdirectories, will be
created for you if you specify the
<code class="literal">DB_CREATE</code> flag on the call to this
method. Otherwise, if the target does not exist, this
method exits with an <code class="literal">ENOENT</code>
error return.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755616490496"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must
be set to 0 or by bitwise inclusively
<span class="bold"><strong>OR</strong></span>'ing together one or more of
the values:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="literal">DB_BACKUP_CLEAN</code>
</p>
<p>
Before performing the backup, first remove all
files from the target backup directory tree.
</p>
</li>
<li>
<p>
<code class="literal">DB_BACKUP_DEEP_COPY</code>
</p>
<p>
Copy databases in any sub-directories in the
environment home and any supplied data directories.
</p>
</li>
<li>
<p>
<code class="literal">DB_BACKUP_FILES</code>
</p>
<p>
Back up all ordinary files that might exist in the
environment, and the environment's subdirectories.
</p>
</li>
<li>
<p>
<code class="literal">DB_BACKUP_NO_LOGS</code>
</p>
<p>
Back up only the <code class="literal">*.db</code>
files. Do not backup the log files.
</p>
</li>
<li>
<p>
<code class="literal">DB_BACKUP_SINGLE_DIR</code>
</p>
<p>
Regardless of the directory structure used by the
source environment, place all back up files in the
single directory identified by the
<code class="literal">target</code> parameter. Use this
option if absolute path names to your environment
directory and the files within that directory are
required by your application.
</p>
</li>
<li>
<p>
<code class="literal">DB_BACKUP_UPDATE</code>
</p>
<p>
Perform an incremental back up, instead of a full
back up. When this option is specified, only log
files are copied to the target directory.
</p>
</li>
<li>
<p>
<code class="literal">DB_CREATE</code>
</p>
<p>
If the target directory does not exist, create it
and any required subdirectories.
</p>
</li>
<li>
<p>
<code class="literal">DB_EXCL</code>
</p>
<p>
Return an <code class="literal">EEXIST</code> error if a
target backup file already exists.
</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755616442896"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::backup()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755616448560"></a>EEXIST</h4>
</div>
</div>
</div>
<p>
<code class="literal">DB_EXCL</code> was specified for the
<code class="literal">flags</code> parameter, and an existing target
file was discovered when attempting to back up a source
file.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755616432704"></a>ENOENT</h4>
</div>
</div>
</div>
<p>
The target directory does not exist and <code class="literal">DB_CREATE</code>
was not specified for the <code class="literal">flags</code>
parameter.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755616465184"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
An invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755616461024"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755616473376"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a>
</p>
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