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 /etc/pg_backrest.conf. The command section defines the location of external commands that are used by .

exe path on the remote host.

Required only if the path to 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. same as local /usr/lib/backrest/bin/pg_backrest The log section defines logging-related settings.

Level for file logging.

The following log levels are supported:

• off - No logging at all (not recommended)
• error - Log only errors
• warn - Log warnings and errors
• info - Log info, warnings, and errors
• debug - Log debug, info, warnings, and errors
• trace - Log trace (very verbose debugging), debug, info, warnings, and errors

debug

Level for console logging.

The following log levels are supported:

• off - No logging at all (not recommended)
• error - Log only errors
• warn - Log warnings and errors
• info - Log info, warnings, and errors
• debug - Log debug, info, warnings, and errors
• trace - Log trace (very verbose debugging), debug, info, warnings, and errors

error The general section defines settings that are shared between multiple operations.

Buffer size for file operations.

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. 16384 - 8388608 32768

Use gzip file compression.

Backup files are compatible with command-line gzip tools. n

Compression level for stored files.

Sets the zlib level to be used for file compression when compress=y. 0-9 9

Compression level for network transfer when compress=n.

Sets the zlib level to be used for protocol compression when compress=n 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 compress-level-network=0. When compress=y the compress-level-network setting is ignored and compress-level is used instead so that the file is only compressed once. SSH compression is always disabled. 0-9 1

remote configuration file.

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. /etc/pg_backrest_remote.conf

Database query timeout.

Sets the timeout for queries against the database. This includes the pg_start_backup() and pg_stop_backup() 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 startfast=y and you know that the database cluster will not generate many WAL segments during the backup). 600

Use a neutral umask.

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 neutral-umask=n in the config file or --no-neutral-umask on the command line. n

Repository path where WAL segments, backups, logs, etc are stored.

The repository serves as both storage and working area for . In a simple installation where the backups are stored locally on the database server there will be only one repository which will contain everything: backups, archives, logs, locks, etc. If the backups are being done remotely then the backup server's repository will contain backups, archives, locks and logs while the database server's repository will contain only locks and logs. However, if asynchronous archiving is enabled then the database server's repository will also contain a spool directory for archive logs that have not yet been pushed to the remote repository. Each system where is installed should have a repository directory configured. Storage requirements vary based on usage. The main backup repository will need the most space as it contains both backups and WAL segments for whatever retention you have specified. The database repository only needs significant space if asynchronous archiving is enabled and then it will act as an overflow for WAL segments and might need to be large depending on your database activity. 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 change over time as your database evolves. /backup/db/backrest

Remote repository path where WAL segments, backups, logs, etc are stored.

The remote repository is relative to the current installation of . On a database server the backup server will be remote and vice versa for the backup server where the database server will be remote. This option is only required if the remote repository has a different path than the local repository. /backup/backrest

Max threads to use in process.

Each thread will perform compression and transfer to make the command run faster, but don't set thread-max so high that it impacts database performance. 4

Max time a thread can run.

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 thread-max=1. 3600 The backup section defines settings related to backup.

Check that WAL segments are present in the archive before backup completes.

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. n

Copy WAL segments needed for consistency to the backup.

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, will ignore them if a recovery.conf file exists and instead use archive_command to fetch WAL segments. Specifying type=none when restoring will not create recovery.conf and force to use the WAL segments in pg_xlog. This will get the database cluster to a consistent state. y

Backup host when operating remotely via SSH.

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. backup.domain.com

Backup host user when backup-host is set.

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

Hardlink files between backups.

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. y

Manifest save threshold during backup.

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 manifest-save-threshold, whichever is greater. 5368709120

Allow resume of failed backup.

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. n

Force a checkpoint to start backup quickly.

Forces a checkpoint (by passing y to the fast parameter of pg_start_backup()) so the backup begins immediately. Otherwise the backup will start after the next regular checkpoint. This feature only works in <= 8.3. y

Stop prior failed backup on new backup.

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 >= 9.3. The setting is disabled by default because it assumes that is the only process doing exclusive online backups. It depends on an advisory lock that only sets so it may abort other processes that do exclusive online backups. Note that base_backup and pg_dump are safe to use with this setting because they do not call pg_start_backup() so are not exclusive. y The archive 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.

Archive WAL segments asynchronously.

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 as soon as the WAL segment is copied locally. y

Limit size of the local asynchronous archive queue when archive-async=y.

After the limit is reached, the following will happen:

1. will notify Postgres that the archive was successfully backed up, then DROP IT.
2. An error will be logged to the console and also to the Postgres log.
3. A stop file will be written in the lock directory and no more archive files will be backed up until it is removed.

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 go down. To start normal archiving again you'll need to remove the stop file which will be located at ${repo-path}/lock/${stanza}-archive.stop where ${repo-path} is the path set in the general section, and ${stanza} is the backup stanza. 1024 The restore section defines settings used for restoring backups.

Restore tablespaces into original or remapped paths.

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

Number of full backups to retain.

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. 2

Number of differential backups to retain.

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. 3

Backup type for WAL retention.

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

Number of backups worth of WAL to retain.

Number of backups worth of archive log to keep. 2 A stanza defines the backup configuration for a specific 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.

Cluster host for operating remotely via SSH.

Used for backups where the database cluster host is different from the backup host. db.domain.com

Cluster host logon user when db-host is set.

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

Cluster data directory.

This should be the same as the data_directory setting in postgresql.conf. Even though this value can be read from postgresql.conf 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 db-path option is tested against the value reported by on every hot backup so it should always be current. /data/db

Cluster port.

Port that is running on. This usually does not need to be specified as most database clusters run on the default port. 6543

Cluster unix socket path.

The unix socket directory that was specified when was started. 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 unix_socket_directory setting in postgressql.conf. /var/run/postgresql Commands are used to execute the various 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 pg_backrest.conf.

configuration file.

Use this option to specify a different configuration file than the default. /var/lib/backrest/pg_backrest.conf

Command stanza.

A stanza is the configuration for a 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. main

Backup a database cluster.

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

Backup type.

The following backup types are supported:

• full - all database cluster files will be copied and there will be no dependencies on previous backups.
• incr - incremental from the last successful backup.
• diff - like an incremental backup but always based on the last full backup.

full

Perform hot backup.

Specifying --no-online prevents from running pg_start_backup() and pg_stop_backup() on the database cluster. In order for this to work should be shut down and will generate an error if it is not. The purpose of this option is to allow cold backups. The pg_xlog directory is copied as-is and archive-check is automatically disabled for the backup. n

Force a cold backup.

When used with --no-start-stop a backup will be run even if thinks that is running. This option should be used with extreme care as it will likely result in a bad backup. 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 postmaster.pid 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. y {[backrest-exe]} --stanza=db --type=full backup Run a full backup on the db stanza. --type can also be set to incr or diff for incremental or differential backups. However, if no full backup exists then a full backup will be forced even if incr or diff is requested.

Push a WAL segment to the archive.

The WAL segment may be pushed immediately to the archive or stored locally depending on the value of archive-async {[backrest-exe]} --stanza=db archive-push %p Accepts a WAL segment from and archives it in the repository defined by repo-path. %p is how specifies the location of the WAL segment to be archived.

Get a WAL segment from the archive.

WAL segments are required for restoring a cluster or maintaining a replica. {[backrest-exe]} --stanza=db archive-get %f %p Retrieves a WAL segment from the repository. This command is used in recovery.conf to restore a backup, perform PITR, or as an alternative to streaming for keeping a replica up to date. %f is how specifies the WAL segment it needs and %p is the location where it should be copied.

Expire backups that exceed retention.

does backup rotation but is not concerned with when the backups were created. If two full backups are configured for retention, will keep two full backups no matter whether they occur two hours or two weeks apart. {[backrest-exe]} --stanza=db expire 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.

Restore a database cluster.

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

Backup set to restore.

The backup set to be restored. latest will restore the latest backup, otherwise provide the name of the backup to restore. 20150131-153358F_20150131-153401I

Restore using delta.

By default the data and tablespace directories are expected to be present but empty. This option performs a delta restore using checksums. y

Force a restore.

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

Create a lock so restores on a stanza cannot run simultaneously.

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

Recovery type.

The following recovery types are supported:

• default - recover to the end of the archive stream.
• immediate - recover only until the database becomes consistent. This option is only supported on >= 9.4.
• name - recover the restore point specified in --target.
• xid - recover to the transaction id specified in --target.
• time - recover to the time specified in --target.
• preserve - preserve the existing recovery.conf file.
• none - no recovery.conf file is written so will attempt to achieve consistency using WAL segments present in pg_xlog. Provide the required WAL segments or use the archive-copy setting to include them with the backup.

xid

Recovery target.

Defines the recovery target when --type is name, xid, or time. 2015-01-30 14:15:11 EST

Stop just before the recovery target is reached.

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

Action to take when recovery target is reached.

The following actions are supported:

• pause - pause when recovery target is reached.
• promote - promote and switch timeline when recovery target is reached.
• shutdown - shutdown server when recovery target is reached.

This option is only supported on >= 9.5. promote

Recover along a timeline.

See recovery_target_timeline in the docs for more information. 3

Set an option in recovery.conf.

See http://www.postgresql.org/docs/X.X/static/recovery-config.html for details on recovery.conf options (replace X.X with your version). This option can be used multiple times. Note: The restore_command option will be automatically generated but can be overridden with this option. Be careful about specifying your own restore_command as is designed to handle this for you. Target Recovery options (recovery_target_name, recovery_target_time, etc.) are generated automatically by and should not be set with this option. Recovery settings can also be set in the restore:recovery-option section of pg_backrest.conf. Since does not start after writing the recovery.conf file, it is always possible to edit/check recovery.conf before manually restarting. primary_conninfo=db.mydomain.com

Modify a tablespace path.

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 9.2 tablespace locations are not stored in pg_tablespace so moving tablespaces can be done with impunity. However, moving a tablespace to the data_directory 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. ts_01=/db/ts_01 {[backrest-exe]} --stanza=db --type=name --target=release restore Restores the latest database cluster backup and then recovers to the release restore point.

Retrieve information about backups.

The info 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 --output=json. The JSON output contains far more information than the text output, however this feature is currently experimental so the format may change between versions.

Output format.

The following output types are supported:

• text - Human-readable summary of backup information.
• json - Exhaustive machine-readable backup information in JSON format.

json {[backrest-exe]} --stanza=db --output=json info Get information about backups in the db stanza. {[backrest-exe]} --output=json info Get information about backups for all stanzas in the repository.

Get help.

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. {[backrest-exe]} help backup Get help for the backup command. {[backrest-exe]} help backup force Get help for the force option of the backup command.

Allow processes to run.

If the processes were previously stopped using the stop command then they can be started again using the start command. Note that this will not immediately start up any processes but they are allowed to run. {[backrest-exe]} --stanza=main start Allows processes to run for the main stanza.

Stop processes from running.

Does not allow any new processes to run. By default running processes will be allowed to complete successfully. Use the --force option to terminate running processes. processes will return an error if they are run after the stop command completes.

Force all processes to stop.

This option will send TERM signals to all running 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 stop --force on the database server will shutdown the backup process on the backup server. y {[backrest-exe]} stop Stop new processes for all stanzas but allow any current process to complete.

Get version.

Displays installed version. {[backrest-exe]} version Get version.