pgbackrest/doc/xml/reference.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE doc SYSTEM "doc.dtd">
<doc title="User Guide">
    <!-- CONFIG -->
    <config title="Configuration Reference">
        <text><backrest/> can be used entirely with command-line parameters but a configuration file is more practical for installations that are complex or set a lot of options. The default location for the configuration file is <file>/etc/pgbackrest.conf</file>.</text>

        <config-section-list title="Settings">
            <!-- CONFIG - COMMAND SECTION -->
            <config-section id="command" name="Command">
                <text>The <setting>command</setting> section defines the location of external commands that are used by <backrest/>.</text>

                <config-key-list>
                    <!-- CONFIG - COMMAND SECTION - CMD-REMOTE KEY -->
                    <config-key id="cmd-remote" name="Remote Command">
                        <summary><backrest/> exe path on the remote host.</summary>

                        <text>Required only if the path to <exe/> is different on the local and remote systems.  If not defined, the remote exe path will be set the same as the local exe path.</text>

                        <default>same as local</default>
                        <example>/usr/lib/backrest/bin/pgbackrest</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - LOG -->
            <config-section id="log" name="Log">
                <text>The <setting>log</setting> section defines logging-related settings.</text>

                <!-- CONFIG - LOG SECTION - LEVEL-FILE KEY -->
                <config-key-list>
                    <config-key id="log-level-file" name="File Log Level">
                        <summary>Level for file logging.</summary>

                        <text>The following log levels are supported:
                        <ul>
                            <li><id>off</id> - No logging at all (not recommended)</li>
                            <li><id>error</id> - Log only errors</li>
                            <li><id>warn</id> - Log warnings and errors</li>
                            <li><id>info</id> - Log info, warnings, and errors</li>
                            <li><id>debug</id> - Log debug, info, warnings, and errors</li>
                            <li><id>trace</id> - Log trace (very verbose debugging), debug, info, warnings, and errors</li>
                        </ul></text>

                        <example>debug</example>
                    </config-key>

                    <!-- CONFIG - LOG SECTION - LEVEL-CONSOLE KEY -->
                    <config-key id="log-level-console" name="Console Log Level">
                        <summary>Level for console logging.</summary>

                        <text>The following log levels are supported:
                        <ul>
                            <li><id>off</id> - No logging at all (not recommended)</li>
                            <li><id>error</id> - Log only errors</li>
                            <li><id>warn</id> - Log warnings and errors</li>
                            <li><id>info</id> - Log info, warnings, and errors</li>
                            <li><id>debug</id> - Log debug, info, warnings, and errors</li>
                            <li><id>trace</id> - Log trace (very verbose debugging), debug, info, warnings, and errors</li>
                        </ul></text>

                        <example>error</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - GENERAL -->
            <config-section id="general" name="General">
                <text>The <setting>general</setting> section defines settings that are shared between multiple operations.</text>

                <!-- CONFIG - GENERAL SECTION - BUFFER-SIZE KEY -->
                <config-key-list>
                    <config-key id="buffer-size" name="Buffer Size">
                        <summary>Buffer size for file operations.</summary>

                        <text>Set the buffer size used for copy, compress, and uncompress functions.  A maximum of 3 buffers will be in use at a time per thread.  An additional maximum of 256K per thread may be used for zlib buffers.</text>

                        <allow>16384 - 8388608</allow>
                        <example>32768</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - COMPRESS -->
                    <config-key id="compress" name="Compress">
                        <summary>Use gzip file compression.</summary>

                        <text>Backup files are compatible with command-line gzip tools.</text>

                        <example>n</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - COMPRESS-LEVEL KEY -->
                    <config-key id="compress-level" name="Compress Level">
                        <summary>Compression level for stored files.</summary>

                        <text>Sets the zlib level to be used for file compression when <setting>compress=y</setting>.</text>

                        <allow>0-9</allow>
                        <example>9</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - COMPRESS-LEVEL-NETWORK KEY -->
                    <config-key id="compress-level-network" name="Network Compress Level">
                        <summary>Compression level for network transfer when <setting>compress=n</setting>.</summary>

                        <text>Sets the zlib level to be used for protocol compression when <setting>compress=n</setting> and the database cluster is not on the same host as the backup.  Protocol compression is used to reduce network traffic but can be disabled by setting <setting>compress-level-network=0</setting>.  When <setting>compress=y</setting> the <setting>compress-level-network</setting> setting is ignored and <setting>compress-level</setting> is used instead so that the file is only compressed once.  SSH compression is always disabled.</text>

                        <allow>0-9</allow>
                        <example>1</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - CONFIG_REMOTE KEY -->
                    <config-key id="config-remote" name="Remote Config">
                        <summary><backrest/> remote configuration file.</summary>

                        <text>Sets the location of the remote configuration file.  This is only required if the remote configuration file is in a different location than the local configuration file.</text>

                        <example>/etc/pgbackrest_remote.conf</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - DB-TIMEOUT KEY -->
                    <config-key id="db-timeout" name="Database Timeout">
                        <summary>Database query timeout.</summary>

                        <text>Sets the timeout for queries against the database.  This includes the <code>pg_start_backup()</code> and <code>pg_stop_backup()</code> functions which can each take a substantial amount of time.  Because of this the timeout should be kept high unless you know that these functions will return quickly (i.e. if you have set <setting>startfast=y</setting> and you know that the database cluster will not generate many WAL segments during the backup).</text>

                        <example>600</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - LOCK-PATH KEY -->
                    <config-key id="lock-path" name="Lock Path">
                        <summary>Path where lock files are stored.</summary>

                        <text>The lock path provides a location for <backrest/> to create lock files to prevent conflicting operations from being run concurrently.</text>

                        <example>/backup/db/lock</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - LOG-PATH KEY -->
                    <config-key id="log-path" name="Log Path">
                        <summary>Path where log files are stored.</summary>

                        <text>The log path provides a location for <backrest/> to store log files.  Note that if <setting>log-level-file=none</setting> then no log path is required.</text>

                        <example>/backup/db/log</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - NEUTRAL-UMASK -->
                    <config-key id="neutral-umask" name="Neutral Umask">
                        <summary>Use a neutral umask.</summary>

                        <text>Sets the umask to 0000 so modes in the repository are created in a sensible way.  The default directory mode is 0750 and default file mode is 0640.  The lock and log directories set the directory and file mode to 0770 and 0660 respectively.

                        To use the executing user's umask instead specify <setting>neutral-umask=n</setting> in the config file or <setting>--no-neutral-umask</setting> on the command line.</text>

                        <example>n</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - LOG-PATH KEY -->
                    <config-key id="spool-path" name="Spool Path">
                        <summary>Path where WAL segments are spooled during async archiving.</summary>

                        <text>When asynchronous archiving is enabled <backrest/> needs a local directory to store WAL segments before they are compressed and moved to the repository.  Depending on the volume of WAL generated this directory could become very large so be sure to plan accordingly.

                        The <setting>max-archive-mb</setting> option can be used to limit the amount of WAL that will be spooled locally.</text>

                        <example>/backup/db/spool</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - REPO-PATH KEY -->
                    <config-key id="repo-path" name="Repository Path">
                        <summary>Repository path where WAL segments and backups stored.</summary>

                        <text>The repository is where <backrest/> stores backup and archives WAL segments.

                        If you are new to backup then it will be difficult to estimate in advance how much space you'll need.  The best thing to do is take some backups then record the size of different types of backups (full/incr/diff) and measure the amount of WAL generated per day.  This will give you a general idea of how much space you'll need, though of course requirements will likely change over time as your database evolves.</text>

                        <example>/backup/db/backrest</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - THEAD-MAX -->
                    <config-key id="thread-max" name="Thread Maximum">
                        <summary>Max threads to use in process.</summary>
                        <text>Each thread will perform compression and transfer to make the command run faster, but don't set <setting>thread-max</setting> so high that it impacts database performance.</text>

                        <example>4</example>
                    </config-key>

                    <!-- CONFIG - GENERAL SECTION - THEAD-TIMEOUT -->
                    <config-key id="thread-timeout" name="Thread Timeout">
                        <summary>Max time a thread can run.</summary>
                        <text>This limits the amount of time (in seconds) that a thread might be stuck due to unforeseen issues executing the command.  Has no affect when <setting>thread-max=1</setting>.</text>

                        <example>3600</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - BACKUP -->
            <config-section id="backup" name="Backup">
                <text>The <setting>backup</setting> section defines settings related to backup.</text>

                <!-- CONFIG - BACKUP SECTION - BACKUP-HOST KEY -->
                <config-key-list>
                    <!-- CONFIG - BACKUP SECTION - ARCHIVE-CHECK -->
                    <config-key id="archive-check" name="Check Archive">
                        <summary>Check that WAL segments are present in the archive before backup completes.</summary>

                        <text>Checks that all WAL segments required to make the backup consistent are present in the WAL archive.  It's a good idea to leave this as the default unless you are using another method for archiving.</text>

                        <example>n</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - ARCHIVE-COPY -->
                    <config-key id="archive-copy" name="Copy Archive">
                        <summary>Copy WAL segments needed for consistency to the backup.</summary>

                        <text>This slightly paranoid option protects against corruption or premature expiration in the WAL segment archive by storing the WAL segments directly in the backup.  PITR won't be possible without the WAL segment archive and this option also consumes more space.

                        Even though WAL segments will be restored with the backup, <postgres/> will ignore them if a <file>recovery.conf</file> file exists and instead use <setting>archive_command</setting> to fetch WAL segments.  Specifying <setting>type=none</setting> when restoring will not create <file>recovery.conf</file> and force <postgres/> to use the WAL segments in pg_xlog.  This will get the database cluster to a consistent state.</text>

                        <example>y</example>
                    </config-key>

                    <config-key id="backup-host" name="Backup Host">
                        <summary>Backup host when operating remotely via SSH.</summary>

                        <text>Make sure that trusted SSH authentication is configured between the db host and the backup host.

                        When backing up to a locally mounted network filesystem this setting is not required.</text>

                        <example>backup.domain.com</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - BACKUP-USER KEY -->
                    <config-key id="backup-user" name="Backup User">
                        <summary>Backup host user when <setting>backup-host</setting> is set.</summary>

                        <text>Defines the user that will be used for operations on the backup server.  Preferably this is not the <id>postgres</id> user but rather some other user like <id>backrest</id>.  If <postgres/> runs on the backup server the <id>postgres</id> user can be placed in the <id>backrest</id> group so it has read permissions on the repository without being able to damage the contents accidentally.</text>

                        <example>backrest</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - HARDLINK -->
                    <config-key id="hardlink" name="Hardlink">
                        <summary>Hardlink files between backups.</summary>

                        <text>Enable hard-linking of files in differential and incremental backups to their full backups.  This gives the appearance that each backup is a full backup.  Be careful, though, because modifying files that are hard-linked can affect all the backups in the set.</text>

                        <example>y</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - MANIFEST-SAVE-THRESHOLD -->
                    <config-key id="manifest-save-threshold" name="Manifest Save Threshold">
                        <summary>Manifest save threshold during backup.</summary>

                        <text>Defines how often the manifest will be saved during a backup (in bytes).  Saving the manifest is important because it stores the checksums and allows the resume function to work efficiently.  The actual threshold used is 1% of the backup size or <setting>manifest-save-threshold</setting>, whichever is greater.</text>

                        <example>5368709120</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - RESUME -->
                    <config-key id="resume" name="Resume">
                        <summary>Allow resume of failed backup.</summary>

                        <text>Defines whether the resume feature is enabled.  Resume can greatly reduce the amount of time required to run a backup after a previous backup of the same type has failed.  It adds complexity, however, so it may be desirable to disable in environments that do not require the feature.</text>

                        <example>n</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - START-FAST -->
                    <config-key id="start-fast" name="Start Fast">
                        <summary>Force a checkpoint to start backup quickly.</summary>

                        <text>Forces a checkpoint (by passing <id>y</id> to the <id>fast</id> parameter of <code>pg_start_backup()</code>) so the backup begins immediately.  Otherwise the backup will start after the next regular checkpoint.

                        This feature only works in <postgres/> &lt;= <id>8.3</id>.</text>

                        <example>y</example>
                    </config-key>

                    <!-- CONFIG - BACKUP SECTION - STOP-AUTO -->
                    <config-key id="stop-auto" name="Stop Auto">
                        <summary>Stop prior failed backup on new backup.</summary>

                        <text>This will only be done if an exclusive advisory lock can be acquired to demonstrate that the prior failed backup process has really stopped.

                        This feature relies on pg_is_in_backup() so only works on <postgres/> >= <id>9.3</id>.

                        The setting is disabled by default because it assumes that <backrest/> is the only process doing exclusive online backups.  It depends on an advisory lock that only <backrest/> sets so it may abort other processes that do exclusive online backups.  Note that <cmd>base_backup</cmd> and <cmd>pg_dump</cmd> are safe to use with this setting because they do not call <code>pg_start_backup()</code> so are not exclusive.</text>

                        <example>y</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - ARCHIVE -->
            <config-section id="archive" name="Archive">
                <text>The <setting>archive</setting> section defines parameters when doing async archiving.  This means that the archive files will be stored locally, then a background process will pick them and move them to the backup.</text>

                <config-key-list>
                    <!-- CONFIG - ARCHIVE SECTION - ARCHIVE-ASYNC KEY -->
                    <config-key id="archive-async" name="Asynchronous Archiving">
                        <summary>Archive WAL segments asynchronously.</summary>

                        <text>WAL segments will be copied to the local repo, then a process will be forked to compress the segment and transfer it to the remote repo if configured.  Control will be returned to <postgres/> as soon as the WAL segment is copied locally.</text>

                        <example>y</example>
                    </config-key>

                    <!-- CONFIG - ARCHIVE SECTION - ARCHIVE-MAX-MB KEY -->
                    <config-key id="archive-max-mb" name="Maximum Archive MB">
                        <summary>Limit size of the local asynchronous archive queue when <setting>archive-async=y</setting>.</summary>

                        <text>After the limit is reached, the following will happen:
                        <ol>
                            <li><backrest/> will notify Postgres that the archive was successfully backed up, then DROP IT.</li>
                            <li>An error will be logged to the console and also to the Postgres log.</li>
                            <li>A stop file will be written in the lock directory and no more archive files will be backed up until it is removed.</li>
                        </ol>If this occurs then the archive log stream will be interrupted and PITR will not be possible past that point.  A new backup will be required to regain full restore capability.

                        The purpose of this feature is to prevent the log volume from filling up at which point Postgres will stop completely.  Better to lose the backup than have <postgres/> go down.

                        To start normal archiving again you'll need to remove the stop file which will be located at <file>${repo-path}/lock/${stanza}-archive.stop</file> where <code>${repo-path}</code> is the path set in the <setting>general</setting> section, and <code>${stanza}</code> is the backup stanza.</text>

                        <example>1024</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - RESTORE -->
            <config-section id="restore" name="Restore">
                <text>The <setting>restore</setting> section defines settings used for restoring backups.</text>

                <config-key-list>
                    <!-- CONFIG - RESTORE SECTION - RECOVERY-OPTION KEY -->
                    <config-key id="recovery-option" name="Recovery Option">
                        <summary>Set an option in <file>recovery.conf</file>.</summary>

                        <text>See http://www.postgresql.org/docs/X.X/static/recovery-config.html for details on recovery.conf options (replace X.X with your <postgres/> version).  This option can be used multiple times.

                        Note: The <setting>restore_command</setting> option will be automatically generated but can be overridden with this option.  Be careful about specifying your own <setting>restore_command</setting> as <backrest/> is designed to handle this for you.  Target Recovery options (recovery_target_name, recovery_target_time, etc.) are generated automatically by <backrest/> and should not be set with this option.

                        Since <backrest/> does not start <postgres/> after writing the <file>recovery.conf</file> file, it is always possible to edit/check <file>recovery.conf</file> before manually restarting.</text>

                        <example>primary_conninfo=db.mydomain.com</example>
                    </config-key>

                    <!-- CONFIG - RESTORE SECTION - TABLESPACE-MAP KEY -->
                    <config-key id="tablespace-map" name="Tablespace Map">
                        <summary>Modify a tablespace path.</summary>

                        <text>Moves a tablespace to a new location during the restore.  This is useful when tablespace locations are not the same on a replica, or an upgraded system has different mount points.

                        Since <postgres/> 9.2 tablespace locations are not stored in pg_tablespace so moving tablespaces can be done with impunity.  However, moving a tablespace to the <setting>data_directory</setting> is not recommended and may cause problems.  For more information on moving tablespaces http://www.databasesoup.com/2013/11/moving-tablespaces.html is a good resource.</text>

                        <example>ts_01=/db/ts_01</example>
                    </config-key>

                    <!-- CONFIG - RESTORE SECTION - TABLESPACE KEY -->
                    <config-key id="tablespace" name="Tablespace">
                        <summary>Restore tablespaces into original or remapped paths.</summary>

                        <text>Defines whether tablespaces will be be restored into their original (or remapped) paths or stored directly under the <path>pg_tblspc</path> path.  Disabling this setting produces compact restores that are convenient for development, staging, etc.  Currently these restores cannot be backed up as <backrest/> expects only links in the <path>pg_tblspc</path> path. If no tablespaces are present this this setting has no effect.</text>

                        <example>n</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - EXPIRE -->
            <config-section id="expire" name="Expire">
                <text>The <setting>expire</setting> section defines how long backups will be retained.  Expiration only occurs when the number of complete backups exceeds the allowed retention.  In other words, if full-retention is set to 2, then there must be 3 complete backups before the oldest will be expired.  Make sure you always have enough space for retention + 1 backups.</text>

                <!-- CONFIG - RETENTION SECTION - FULL-RETENTION KEY -->
                <config-key-list>
                    <config-key id="retention-full" name="Full Retention">
                        <summary>Number of full backups to retain.</summary>

                        <text>When a full backup expires, all differential and incremental backups associated with the full backup will also expire.  When not defined then all full backups will be kept.</text>

                        <example>2</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - DIFFERENTIAL-RETENTION KEY -->
                    <config-key id="retention-diff" name="Differential Retention">
                        <summary>Number of differential backups to retain.</summary>

                        <text>When a differential backup expires, all incremental backups associated with the differential backup will also expire.  When not defined all differential backups will be kept until the full backups they depend on expire.</text>

                        <example>3</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - ARCHIVE-RETENTION-TYPE KEY -->
                    <config-key id="retention-archive-type" name="Archive Retention Type">
                        <summary>Backup type for WAL retention.</summary>

                        <text>If set to <setting>full</setting> <backrest/> will keep archive logs for the number of full backups defined by <setting>retention-archive</setting>.  If set to <setting>diff</setting> (differential) <backrest/> will keep archive logs for the number of full and differential backups defined by <setting>retention-archive</setting>.  If set to <setting>incr</setting> (incremental) <backrest/> will keep archive logs for the number of full, differential, and incremental backups defined by <setting>retention-archive</setting>.</text>

                        <example>diff</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - ARCHIVE-RETENTION KEY -->
                    <config-key id="retention-archive" name="Archive Retention">
                        <summary>Number of backups worth of WAL to retain.</summary>

                        <text>Number of backups worth of archive log to keep.</text>

                        <example>2</example>
                    </config-key>
                </config-key-list>
            </config-section>

            <!-- CONFIG - STANZA -->
            <config-section id="stanza" name="Stanza">
                <text>A stanza defines the backup configuration for a specific <postgres/> database cluster.  The stanza section must define the database cluster path and host/user if the database cluster is remote.  Also, any global configuration sections can be overridden to define stanza-specific settings.</text>

                <!-- CONFIG - RETENTION SECTION - DB-HOST KEY -->
                <config-key-list>
                    <config-key id="db-host" name="Database Host">
                        <summary>Cluster host for operating remotely via SSH.</summary>

                        <text>Used for backups where the database cluster host is different from the backup host.</text>

                        <example>db.domain.com</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - DB-USER KEY -->
                    <config-key id="db-user" name="Database User">
                        <summary>Cluster host logon user when <setting>db-host</setting> is set.</summary>

                        <text>This user will also own the remote <backrest/> process and will initiate connections to <postgres/>.  For this to work correctly the user should be the <postgres/> database cluster owner which is generally <id>postgres</id>, the default.</text>

                        <example>db_owner</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - DB-PATH KEY -->
                    <config-key id="db-path" name="Database Path">
                        <summary>Cluster data directory.</summary>

                        <text>This should be the same as the <setting>data_directory</setting> setting in <file>postgresql.conf</file>.  Even though this value can be read from <file>postgresql.conf</file> or the database cluster it is prudent to set it in case those resources are not available during a restore or cold backup scenario.

                        The <setting>db-path</setting> option is tested against the value reported by <postgres/> on every hot backup so it should always be current.</text>

                        <example>/data/db</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - DB-PORT KEY -->
                    <config-key id="db-port" name="Database Port">
                        <summary>Cluster port.</summary>

                        <text>Port that <postgres/> is running on.  This usually does not need to be specified as most database clusters run on the default port.</text>

                        <example>6543</example>
                    </config-key>

                    <!-- CONFIG - RETENTION SECTION - DB-SOCKET-PATH KEY -->
                    <config-key id="db-socket-path" name="Database Socket Path">
                        <summary>Cluster unix socket path.</summary>

                        <text>The unix socket directory that was specified when <postgres/> was started.  <backrest/> will automatically look in the standard location for your OS so there usually no need to specify this setting unless the socket directory was explicitly modified with the <setting>unix_socket_directory</setting> setting in <file>postgressql.conf</file>.</text>

                        <example>/var/run/postgresql</example>
                    </config-key>
                </config-key-list>
            </config-section>
        </config-section-list>
    </config>

    <!-- COMMAND -->
    <operation title="Command Reference">
        <text>Commands are used to execute the various <backrest/> functions.  Here the command options are listed exhaustively, that is, each option applicable to a command is listed with that command even if it applies to one or more other commands.  This includes all the options that may also configured in <file>pgbackrest.conf</file>.</text>

        <operation-general title="General Options">
            <option-list>
                <!-- OPERATION - GENERAL - CONFIG OPTION -->
                <option id="config" name="Config">
                    <summary><backrest/> configuration file.</summary>

                    <text>Use this option to specify a different configuration file than the default.</text>

                    <example>/var/lib/backrest/pgbackrest.conf</example>
                </option>

                <!-- OPERATION - GENERAL - STANZA OPTION -->
                <option id="stanza" name="Stanza">
                    <summary>Command stanza.</summary>

                    <text>A stanza is the configuration for a <postgres/> database cluster that defines where it is located, how it will be backed up, archiving options, etc.  Most db servers will only have one Postgres database cluster and therefore one stanza, whereas backup servers will have a stanza for every database cluster that needs to be backed up.

                    It is tempting to name the stanza after the primary cluster but a better name describes the databases contained in the cluster.  Because the stanza name will be used for the primary and all replicas it is more appropriate to choose a name that describes the actual function of the cluster, such as app or dw, rather than the local cluster name, such as main or prod.</text>

                    <example>main</example>
                </option>
            </option-list>
        </operation-general>

        <command-list title="Commands">
            <!-- OPERATION - BACKUP COMMAND -->
            <command id="backup" name="Backup">
                <summary>Backup a database cluster.</summary>

                <text><backrest/> does not have a built-in scheduler so it's best to run it from cron or some other scheduling mechanism.</text>

                <option-list>
                    <!-- OPERATION - BACKUP COMMAND - TYPE OPTION -->
                    <option id="type" name="Type">
                        <summary>Backup type.</summary>

                        <text>The following backup types are supported:
                            <ul>
                                <li><id>full</id> - all database cluster files will be copied and there will be no dependencies on previous backups.</li>
                                <li><id>incr</id> - incremental from the last successful backup.</li>
                                <li><id>diff</id> - like an incremental backup but always based on the last full backup.</li>
                            </ul></text>

                        <example>full</example>
                    </option>

                    <!-- OPERATION - BACKUP COMMAND - ONLINE OPTION -->
                    <option id="online" name="Online">
                        <summary>Perform hot backup.</summary>

                        <text>Specifying --no-online prevents <backrest/> from running <code>pg_start_backup()</code> and <code>pg_stop_backup()</code> on the database cluster.  In order for this to work <postgres/> should be shut down and <backrest/> will generate an error if it is not.

                        The purpose of this option is to allow cold backups.  The <path>pg_xlog</path> directory is copied as-is and <setting>archive-check</setting> is automatically disabled for the backup.</text>

                        <example>n</example>
                    </option>

                    <!-- OPERATION - BACKUP COMMAND - FORCE OPTION -->
                    <option id="force" name="Force">
                        <summary>Force a cold backup.</summary>

                        <text>When used with <br-option>--no-start-stop</br-option> a backup will be run even if <backrest/> thinks that <postgres/> is running.  <b>This option should be used with extreme care as it will likely result in a bad backup.</b>

                        There are some scenarios where a backup might still be desirable under these conditions.  For example, if a server crashes and the database cluster volume can only be mounted read-only, it would be a good idea to take a backup even if <file>postmaster.pid</file> is present.  In this case it would be better to revert to the prior backup and replay WAL, but possibly there is a very important transaction in a WAL segment that did not get archived.</text>

                        <example>y</example>
                    </option>
                </option-list>

                <command-example-list>
                    <command-example title="Full Backup">
                        <text><code-block title="">
                            {[backrest-exe]} --stanza=db --type=full backup
                        </code-block>
                        Run a <id>full</id> backup on the <id>db</id> stanza.  <br-option>--type</br-option> can also be set to <id>incr</id> or <id>diff</id> for incremental or differential backups.  However, if no <id>full</id> backup exists then a <id>full</id> backup will be forced even if <id>incr</id> or <id>diff</id> is requested.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - ARCHIVE-PUSH COMMAND -->
            <command id="archive-push" name="Archive Push">
                <summary>Push a WAL segment to the archive.</summary>

                <text>The WAL segment may be pushed immediately to the archive or stored locally depending on the value of <setting>archive-async</setting></text>

                <command-example-list>
                    <command-example>
                        <text><code-block title="">
                            {[backrest-exe]} --stanza=db archive-push %p
                        </code-block>
                        Accepts a WAL segment from <postgres/> and archives it in the repository defined by <setting>repo-path</setting>.  <id>%p</id> is how <postgres/> specifies the location of the WAL segment to be archived.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - ARCHIVE-GET COMMAND -->
            <command id="archive-get" name="Archive Get">
                <summary>Get a WAL segment from the archive.</summary>

                <text>WAL segments are required for restoring a <postgres/> cluster or maintaining a replica.</text>

                <command-example-list>
                    <command-example>
                        <text><code-block title="">
                            {[backrest-exe]} --stanza=db archive-get %f %p
                        </code-block>
                        Retrieves a WAL segment from the repository.  This command is used in <file>recovery.conf</file> to restore a backup, perform PITR, or as an alternative to streaming for keeping a replica up to date.  <id>%f</id> is how <postgres/> specifies the WAL segment it needs and <id>%p</id> is the location where it should be copied.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - EXPIRE COMMAND -->
            <command id="expire" name="Expire">
                <summary>Expire backups that exceed retention.</summary>

                <text><backrest/> does backup rotation but is not concerned with when the backups were created.  If two full backups are configured for retention, <backrest/> will keep two full backups no matter whether they occur two hours or two weeks apart.</text>

                <command-example-list>
                    <command-example>
                        <text><code-block title="">
                            {[backrest-exe]} --stanza=db expire
                        </code-block>
                        Expire (rotate) any backups that exceed the defined retention.  Expiration is run automatically after every successful backup, so there is no need to run this command separately unless you have reduced retention, usually to free up some space.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - RESTORE COMMAND -->
            <command id="restore" name="Restore">
                <summary>Restore a database cluster.</summary>

                <text>This command is generally run manually, but there are instances where it might be automated.</text>

                <option-list>
                    <!-- OPERATION - RESTORE COMMAND - SET OPTION -->
                    <option id="set" name="Set">
                        <summary>Backup set to restore.</summary>

                        <text>The backup set to be restored.  <id>latest</id> will restore the latest backup, otherwise provide the name of the backup to restore.</text>
                        <example>20150131-153358F_20150131-153401I</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - DELTA OPTION -->
                    <option id="delta" name="Delta">
                        <summary>Restore using delta.</summary>

                        <text>By default the <postgres/> data and tablespace directories are expected to be present but empty.  This option performs a delta restore using checksums.</text>

                        <example>y</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - FORCE OPTION -->
                    <option id="force" name="Force">
                        <summary>Force a restore.</summary>

                        <text>By itself this option forces the <postgres/> data and tablespace paths to be completely overwritten.  In combination with <br-option>--delta</br-option> a timestamp/size delta will be performed instead of using checksums.</text>

                        <example>y</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - LOCK OPTION -->
                    <option id="lock" name="Lock">
                        <summary>Create a lock so restores on a stanza cannot run simultaneously.</summary>

                        <text>Locking during restores is enabled by default but can be disabled using --no-lock.  Be <i>very</i> careful when disabling this option because simultaneous restores to a single path might result in a corrupt cluster.</text>

                        <example>n</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - TYPE OPTION -->
                    <option id="type" name="Type">
                        <summary>Recovery type.</summary>

                        <text>The following recovery types are supported:
                        <ul>
                            <li><id>default</id> - recover to the end of the archive stream.</li>
                            <li><id>immediate</id> - recover only until the database becomes consistent. This option is only supported on <postgres/> &gt;= 9.4.</li>
                            <li><id>name</id> - recover the restore point specified in <br-option>--target</br-option>.</li>
                            <li><id>xid</id> - recover to the transaction id specified in <br-option>--target</br-option>.</li>
                            <li><id>time</id> - recover to the time specified in <br-option>--target</br-option>.</li>
                            <li><id>preserve</id> - preserve the existing <file>recovery.conf</file> file.</li>
                            <li><id>none</id> - no <file>recovery.conf</file> file is written so <postgres/> will attempt to achieve consistency using WAL segments present in <path>pg_xlog</path>.  Provide the required WAL segments or use the <setting>archive-copy</setting> setting to include them with the backup.</li>
                        </ul></text>
                        <example>xid</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - TARGET OPTION -->
                    <option id="target" name="Target">
                        <summary>Recovery target.</summary>

                        <text>Defines the recovery target when <br-option>--type</br-option> is <id>name</id>, <id>xid</id>, or <id>time</id>.</text>
                        <example>2015-01-30 14:15:11 EST</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - TARGET-EXCLUSIVE OPTION -->
                    <option id="target-exclusive" name="Target Exclusive">
                        <summary>Stop just before the recovery target is reached.</summary>

                        <text>Defines whether recovery to the target would be exclusive (the default is inclusive) and is only valid when <br-option>--type</br-option> is <id>time</id> or <id>xid</id>.  For example, using <br-option>--target-exclusive</br-option> would exclude the contents of transaction <id>1007</id> when <br-option>--type=xid</br-option> and <br-option>--target=1007</br-option>.  See the <setting>recovery_target_inclusive</setting> option in the <postgres/> docs for more information.</text>

                        <example>n</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - TARGET-RESUME OPTION -->
                    <option id="target-action" name="Target Action">
                        <summary>Action to take when recovery target is reached.</summary>

                        <text>The following actions are supported:
                        <ul>
                            <li><id>pause</id> - pause when recovery target is reached.</li>
                            <li><id>promote</id> - promote and switch timeline when recovery target is reached.</li>
                            <li><id>shutdown</id> - shutdown server when recovery target is reached.</li>
                        </ul>This option is only supported on <postgres/> &gt;= 9.5.</text>

                        <example>promote</example>
                    </option>

                    <!-- OPERATION - RESTORE COMMAND - TARGET-TIMELINE OPTION -->
                    <option id="target-timeline" name="Target Timeline">
                        <summary>Recover along a timeline.</summary>

                        <text>See <setting>recovery_target_timeline</setting> in the <postgres/> docs for more information.</text>

                        <example>3</example>
                    </option>
                </option-list>

                <command-example-list>
                    <command-example title="Restore Latest">
                        <text><code-block title="">
                                {[backrest-exe]} --stanza=db --type=name --target=release restore
                            </code-block>
                            Restores the latest database cluster backup and then recovers to the <id>release</id> restore point.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - INFO COMMAND -->
            <command id="info" name="Info">
                <summary>Retrieve information about backups.</summary>

                <text>The <cmd>info</cmd> command operates on a single stanza or all stanzas.  Text output is the default and gives a human-readable summary of backups for the stanza(s) requested.  This format is subject to change with any release.

                For machine-readable output use <setting>--output=json</setting>.  The JSON output contains far more information than the text output, however <b>this feature is currently experimental so the format may change between versions</b>.</text>

                <option-list>
                    <!-- OPERATION - INFO COMMAND - OUTPUT OPTION -->
                    <option id="output" name="Output">
                        <summary>Output format.</summary>

                        <text>The following output types are supported:
                        <ul>
                            <li><id>text</id> - Human-readable summary of backup information.</li>
                            <li><id>json</id> - Exhaustive machine-readable backup information in JSON format.</li>
                        </ul></text>

                        <example>json</example>
                    </option>
                </option-list>

                <command-example-list>
                    <command-example title="Information for a single stanza">
                        <text><code-block title="">
                            {[backrest-exe]} --stanza=db --output=json info
                        </code-block>

                        Get information about backups in the <id>db</id> stanza.</text>
                    </command-example>

                    <command-example title="Information for all stanzas">
                        <text><code-block title="">
                            {[backrest-exe]} --output=json info
                        </code-block>

                        Get information about backups for all stanzas in the repository.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - HELP COMMAND -->
            <command id="help" name="Help">
                <summary>Get help.</summary>

                <text>Three levels of help are provided.  If no command is specified then general help will be displayed.  If a command is specified then a full description of the command will be displayed along with a list of valid options.  If an option is specified in addition to a command then the a full description of the option as it applies to the command will be displayed.</text>

                <command-example-list>
                    <command-example title="Help for the backup command">
                        <text><code-block title="">
                            {[backrest-exe]} help backup
                        </code-block>

                        Get help for the backup command.</text>
                    </command-example>

                    <command-example title="Help for backup command, --force option">
                        <text><code-block title="">
                            {[backrest-exe]} help backup force
                        </code-block>

                        Get help for the force option of the backup command.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - START COMMAND -->
            <command id="start" name="Start">
                <summary>Allow <backrest/> processes to run.</summary>

                <text>If the <backrest/> processes were previously stopped using the <cmd>stop</cmd> command then they can be started again using the <cmd>start</cmd> command.  Note that this will not immediately start up any <backrest/> processes but they are allowed to run.</text>

                <command-example-list>
                    <command-example title="Start processes for stanza main">
                        <text><code-block title="">
                            {[backrest-exe]} --stanza=main start
                        </code-block>

                        Allows <backrest/> processes to run for the <id>main</id> stanza.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - STOP COMMAND -->
            <command id="stop" name="Stop">
                <summary>Stop <backrest/> processes from running.</summary>

                <text>Does not allow any new <backrest/> processes to run.  By default running processes will be allowed to complete successfully.  Use the <setting>--force</setting> option to terminate running processes.

                <backrest/> processes will return an error if they are run after the stop command completes.</text>

                <option-list>
                    <!-- OPERATION - STOP COMMAND - FORCE OPTION -->
                    <option id="force" name="Force">
                        <summary>Force all <backrest/> processes to stop.</summary>

                        <text>This option will send TERM signals to all running <backrest/> processes to effect a graceful but immediate shutdown.  Note that this will also shutdown processes that were initiated on another system but have remotes running on the current system.  For instance, if a backup was started on the backup server then running <cmd>stop --force</cmd> on the database server will shutdown the backup process on the backup server.</text>

                        <example>y</example>
                    </option>
                </option-list>

                <command-example-list>
                    <command-example title="Stop processes for all stanzas">
                        <text><code-block title="">
                            {[backrest-exe]} stop
                        </code-block>

                        Stop new <backrest/> processes for all stanzas but allow any current process to complete.</text>
                    </command-example>
                </command-example-list>
            </command>

            <!-- OPERATION - VERSION COMMAND -->
            <command id="version" name="Version">
                <summary>Get version.</summary>

                <text>Displays installed <backrest/> version.</text>

                <command-example-list>
                    <command-example title="Get version">
                        <text><code-block title="">
                            {[backrest-exe]} version
                        </code-block>

                        Get <backrest/> version.</text>
                    </command-example>
                </command-example-list>
            </command>
        </command-list>
    </operation>
</doc>