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<th colspan="3" align="center">db_hotbackup</th>
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<th width="60%" align="center">Appendix A.
Berkeley DB Command Line Utilities
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<div class="sect1" lang="en" xml:lang="en">
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<div>
<h2 class="title" style="clear: both"><a id="db_hotbackup"></a>db_hotbackup</h2>
</div>
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</div>
<pre class="programlisting">db_hotbackup [-cDEguVv] [-d data_dir ...] [-h home]
[-l log_dir] [-P password] -b backup_dir </pre>
<p>
The <span class="command"><strong>db_hotbackup</strong></span> utility creates "hot backup" or "hot failover"
snapshots of Berkeley DB database environments. Hot backups can
also be performed using the
<a class="xref" href="envbackup.html" title="DbEnv::backup()">DbEnv::backup()</a>
or
<a class="xref" href="envdbbackup.html" title="DbEnv::dbbackup()">DbEnv::dbbackup()</a>
methods.
</p>
<p>
The <span class="command"><strong>db_hotbackup</strong></span> utility performs the following steps:
</p>
<div class="orderedlist">
<ol type="1">
<li>
<p>
Sets the
<a class="xref" href="envset_flags.html#set_flags_DB_HOTBACKUP_IN_PROGRESS">
<code class="literal">DB_HOTBACKUP_IN_PROGRESS</code>
</a>
flag in the home database environment.
</p>
</li>
<li>
<p>
If the <span class="bold"><strong>-c</strong></span> option is specified,
checkpoint the source home database environment, and remove any
unnecessary log files.
</p>
</li>
<li>
<p>
If the target directory for the backup does not exist, it is created
with mode read-write-execute for the owner.
</p>
<p>
If the target directory for the backup does exist and the <span class="bold"><strong>-u</strong></span> option was specified, all log files in the
target directory are removed; if the <span class="bold"><strong>-u</strong></span> option was not specified, all files in the
target directory are removed.
</p>
</li>
<li>
<p>
If the <span class="bold"><strong>-u</strong></span> option was not specified,
copy application-specific files found in the database environment home
directory, and any directories specified using the <span class="bold"><strong>-d</strong></span> option, into the target directory for the
backup.
</p>
</li>
<li>
<p>
Copy all log files found in the directory specified by the <span class="bold"><strong>-l</strong></span> option (or in the database environment home
directory, if no <span class="bold"><strong>-l</strong></span> option was
specified), into the target directory for the backup.
</p>
</li>
<li>
<p>
Perform catastrophic recovery in the target directory for the backup.
</p>
</li>
<li>
<p>
Remove any unnecessary log files from the target directory for the
backup.
</p>
</li>
<li>
<p>
Reset the
<a class="xref" href="envset_flags.html#set_flags_DB_HOTBACKUP_IN_PROGRESS">
<code class="literal">DB_HOTBACKUP_IN_PROGRESS</code>
</a>
flag in the environment.
</p>
</li>
</ol>
</div>
<p>
The <span class="command"><strong>db_hotbackup</strong></span> utility does not resolve pending transactions that
are in the prepared state.
<span>
Applications that use
<a class="xref" href="txnprepare.html" title="DbTxn::prepare()">DbTxn::prepare()</a> must specify
<a class="link" href="envopen.html#envopen_DB_RECOVER_FATAL">DB_RECOVER_FATAL</a>
when opening the environment, and run
<a class="xref" href="txnrecover.html" title="DbEnv::txn_recover()">DbEnv::txn_recover()</a> to
resolve any pending transactions, when failing over to the backup.
</span>
</p>
<p>
The options are as follows:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="bold"><strong>-b</strong></span>
</p>
<p>
Specify the target directory for the backup.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-c</strong></span>
</p>
<p>
Before performing the backup, checkpoint the source database
environment and remove any log files that are no longer required in
that environment. <span class="bold"><strong>To avoid making catastrophic
recovery impossible, log file removal must be integrated with log file
archival.</strong></span>
</p>
</li>
<li>
<p>
<span class="bold"><strong>-D</strong></span>
</p>
<p>
Use the data and log directories listed in a <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a>
configuration file in the source directory. This option
has four effects:
</p>
<div class="itemizedlist">
<ul type="circle">
<li>
<p>
The specified data and log directories will be created relative to the
target directory, with mode read-write-execute owner, if they do not
already exist.
</p>
</li>
<li>
<p>
In step #3 above, all files in any source data
directories specified in the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file will
be copied to the target data directories.
</p>
</li>
<li>
<p>
In step #4 above, log files will be copied from
any log directory specified in the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a>
file, instead of from the default locations.
</p>
</li>
<li>
<p>
The <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> configuration file will be copied
from the source directory to the target directory,
and subsequently used for configuration if recovery
is run in the target directory.
</p>
</li>
</ul>
</div>
<p>
Care should be taken with the <span class="bold"><strong>-D</strong></span>
option where data and log directories are named relative to the source
directory but are not subdirectories (that is, the name includes the
element "..") Specifically, the constructed target directory names
must be meaningful and distinct from the source directory names,
otherwise running recovery in the target directory might corrupt the
source data files.
</p>
<p>
<span class="bold"><strong>It is an error to use absolute pathnames for
data or log directories in this mode, as the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a>
configuration file copied into the target directory would
then point at the source directories and running recovery
would corrupt the source data files.</strong></span>
</p>
</li>
<li>
<p>
<span class="bold"><strong>-d</strong></span>
</p>
<p>
Specify one or more directories that contain data files to be copied
to the target directory.
</p>
<p>
<span class="bold"><strong>As all database files are copied into a single
target directory, files named the same, stored in different source
directories, would overwrite each other when copied to the target
directory.</strong></span>
</p>
<p>
Please note the database environment recovery log references database
files as they are named by the application program. <span class="bold"><strong>If the application uses absolute or relative pathnames to
name database files, (rather than filenames and the
<a class="xref" href="envset_data_dir.html" title="DbEnv::set_data_dir()">DbEnv::set_data_dir()</a>
method or the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> configuration file to specify
filenames), running recovery in the target directory may
not properly find the copies of the files or might even
find the source files, potentially resulting in
corruption.</strong></span>
</p>
</li>
<li>
<p>
<span class="bold"><strong>-F</strong></span>
</p>
<p>
Directly copy from the filesystem. This option can
<span class="bold"><strong>CORRUPT</strong></span> the backup if used
while the environment is active and the operating system does
not support atomic file system reads. This option is known to
be safe only on UNIX systems, not Linux or Windows systems.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-g</strong></span>
</p>
<p>
Turn on debugging options. In particular this will leave the
log files in the backup directory after running recovery.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-h</strong></span>
</p>
<p>
Specify the source directory for the backup. That is, the
database environment home directory.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-l</strong></span>
</p>
<p>
Specify a source directory that contains log files; if none is
specified, the database environment home directory will be searched
for log files. If a relative path is specified, the path
is evaluated relative to the home directory.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-P</strong></span>
</p>
<p>
Specify an environment password. Although Berkeley DB utilities
overwrite password strings as soon as possible, be aware there may be
a window of vulnerability on systems where unprivileged users can see
command-line arguments or where utilities are not able to overwrite
the memory containing the command-line arguments.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-u</strong></span>
</p>
<p>
Update a pre-existing hot backup snapshot by copying in new log files.
If the <span class="bold"><strong>-u</strong></span> option is specified, no
databases will be copied into the target directory. If applications
that update the environment are using the transactional bulk insert
optimization, this option must be used with special care.
For more information, see the
section on Hot Backup in the <span class="emphasis"><em>Getting Started
With Transaction Processing Guide</em></span>.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-V</strong></span>
</p>
<p>
Write the library version number to the standard output, and exit.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-v</strong></span>
</p>
<p>
Run in verbose mode, listing operations as they are done.
</p>
</li>
</ul>
</div>
<p>
The <span class="command"><strong>db_hotbackup</strong></span> utility uses a Berkeley DB
environment (as described for the <span class="bold"><strong>-h</strong></span> option, the environment variable
<span class="bold"><strong>DB_HOME</strong></span>, or because the
utility was run in a directory containing a Berkeley DB
environment).
In order to avoid environment corruption when using a Berkeley DB
environment, <span class="command"><strong>db_hotbackup</strong></span> should always be given the chance to detach
from the environment and exit gracefully. To cause <span class="command"><strong>db_hotbackup</strong></span> to
release all environment resources and exit cleanly, send it an
interrupt signal (SIGINT).
</p>
<p>
The <span class="command"><strong>db_hotbackup</strong></span> utility exits 0 on success, and >0 if an error
occurs.
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp10688784"></a>Environment Variables</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp10695888"></a>DB_HOME</h4>
</div>
</div>
</div>
<p>
If the <span class="bold"><strong>-h</strong></span> option is not specified and
the environment variable DB_HOME is set, it is used as the path of the
database home, as described in the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method.
</p>
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