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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head>
<title>pgBackRest User Guide - RHEL 7-8 / PostgreSQL 9.6-11
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<meta property="og:site_name" content="pgBackRest - Reliable PostgreSQL Backup & Restore"></meta>
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<meta name="description" content="The pgBackRest User Guide demonstrates how to quickly and easily setup pgBackRest for your PostgreSQL database. Step-by-step instructions lead the user through all the important features of the fastest, most reliable PostgreSQL backup and restore solution."></meta>
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</head><body><div class="page-header"><div class="page-header-title">
pgBackRest User Guide
</div><div class="page-header-subtitle">
RHEL 7-8 / PostgreSQL 9.6-11
</div></div><div class="page-menu"><div class="menu-body"><div class="menu"><a class="menu-link" href="/">
Home
</a></div><div class="menu"><a class="menu-link" href="user-guide-index.html">
User Guides
</a></div><div class="menu"><a class="menu-link" href="release.html">
Releases
</a></div><div class="menu"><a class="menu-link" href="configuration.html">
Configuration
</a></div><div class="menu"><a class="menu-link" href="command.html">
Commands
</a></div><div class="menu"><a class="menu-link" href="faq.html">
FAQ
</a></div><div class="menu"><a class="menu-link" href="metric.html">
Metrics
</a></div></div></div><div class="page-toc"><div class="page-toc-header"><div class="page-toc-title">
Table of Contents
</div></div><div class="page-toc-body"><div class="section1-toc"><div class="section1-toc-number">
1
</div><div class="section1-toc-title"><a href="#introduction">
Introduction
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
2
</div><div class="section1-toc-title"><a href="#concept">
Concepts
</a></div><div class="section2-toc"><div class="section2-toc-number">
2.1
</div><div class="section2-toc-title"><a href="#concept/backup">
Backup
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
2.2
</div><div class="section2-toc-title"><a href="#concept/restore">
Restore
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
2.3
</div><div class="section2-toc-title"><a href="#concept/wal">
Write Ahead Log (WAL)
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
2.4
</div><div class="section2-toc-title"><a href="#concept/encryption">
Encryption
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
3
</div><div class="section1-toc-title"><a href="#upgrading">
Upgrading pgBackRest
</a></div><div class="section2-toc"><div class="section2-toc-number">
3.1
</div><div class="section2-toc-title"><a href="#upgrading/v1-v2">
Upgrading pgBackRest from v1 to v2
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
4
</div><div class="section1-toc-title"><a href="#build">
Build
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
5
</div><div class="section1-toc-title"><a href="#installation">
Installation
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
6
</div><div class="section1-toc-title"><a href="#quickstart">
Quick Start
</a></div><div class="section2-toc"><div class="section2-toc-number">
6.1
</div><div class="section2-toc-title"><a href="#quickstart/setup-demo-cluster">
Setup Demo Cluster
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.2
</div><div class="section2-toc-title"><a href="#quickstart/configure-stanza">
Configure Cluster Stanza
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.3
</div><div class="section2-toc-title"><a href="#quickstart/create-repository">
Create the Repository
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.4
</div><div class="section2-toc-title"><a href="#quickstart/configure-archiving">
Configure Archiving
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.5
</div><div class="section2-toc-title"><a href="#quickstart/retention">
Configure Retention
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.6
</div><div class="section2-toc-title"><a href="#quickstart/configure-encryption">
Configure Repository Encryption
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.7
</div><div class="section2-toc-title"><a href="#quickstart/create-stanza">
Create the Stanza
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.8
</div><div class="section2-toc-title"><a href="#quickstart/check-configuration">
Check the Configuration
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.9
</div><div class="section2-toc-title"><a href="#quickstart/perform-backup">
Perform a Backup
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.10
</div><div class="section2-toc-title"><a href="#quickstart/schedule-backup">
Schedule a Backup
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.11
</div><div class="section2-toc-title"><a href="#quickstart/backup-info">
Backup Information
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
6.12
</div><div class="section2-toc-title"><a href="#quickstart/perform-restore">
Restore a Backup
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
7
</div><div class="section1-toc-title"><a href="#monitor">
Monitoring
</a></div><div class="section2-toc"><div class="section2-toc-number">
7.1
</div><div class="section2-toc-title"><a href="#monitor/postgresql">
In <span class="postgres">PostgreSQL</span>
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
8
</div><div class="section1-toc-title"><a href="#retention">
Retention
</a></div><div class="section2-toc"><div class="section2-toc-number">
8.1
</div><div class="section2-toc-title"><a href="#retention/full">
Full Backup Retention
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
8.2
</div><div class="section2-toc-title"><a href="#retention/diff">
Differential Backup Retention
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
8.3
</div><div class="section2-toc-title"><a href="#retention/archive">
Archive Retention
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
9
</div><div class="section1-toc-title"><a href="#restore">
Restore
</a></div><div class="section2-toc"><div class="section2-toc-number">
9.1
</div><div class="section2-toc-title"><a href="#restore/ownership">
File Ownership
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
9.2
</div><div class="section2-toc-title"><a href="#restore/option-delta">
Delta Option
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
9.3
</div><div class="section2-toc-title"><a href="#restore/option-db-include">
Restore Selected Databases
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
10
</div><div class="section1-toc-title"><a href="#pitr">
Point-in-Time Recovery
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
11
</div><div class="section1-toc-title"><a href="#multi-repo">
Multiple Repositories
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
12
</div><div class="section1-toc-title"><a href="#azure-support">
Azure-Compatible Object Store Support
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
13
</div><div class="section1-toc-title"><a href="#s3-support">
S3-Compatible Object Store Support
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
14
</div><div class="section1-toc-title"><a href="#gcs-support">
GCS-Compatible Object Store Support
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
15
</div><div class="section1-toc-title"><a href="#delete-stanza">
Delete a Stanza
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
16
</div><div class="section1-toc-title"><a href="#repo-host">
Dedicated Repository Host
</a></div><div class="section2-toc"><div class="section2-toc-number">
16.1
</div><div class="section2-toc-title"><a href="#repo-host/install">
Installation
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
16.2
</div><div class="section2-toc-title"><a href="#repo-host/config">
Configuration
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
16.3
</div><div class="section2-toc-title"><a href="#repo-host/setup-tls">
Setup TLS Server
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
16.4
</div><div class="section2-toc-title"><a href="#repo-host/stanza-create">
Create and Check Stanza
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
16.5
</div><div class="section2-toc-title"><a href="#repo-host/perform-backup">
Perform a Backup
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
16.6
</div><div class="section2-toc-title"><a href="#repo-host/perform-restore">
Restore a Backup
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
17
</div><div class="section1-toc-title"><a href="#parallel-backup-restore">
Parallel Backup / Restore
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
18
</div><div class="section1-toc-title"><a href="#start-stop">
Starting and Stopping
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
19
</div><div class="section1-toc-title"><a href="#replication">
Replication
</a></div><div class="section2-toc"><div class="section2-toc-number">
19.1
</div><div class="section2-toc-title"><a href="#replication/installation">
Installation
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
19.2
</div><div class="section2-toc-title"><a href="#replication/hot-standby">
Hot Standby
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
19.3
</div><div class="section2-toc-title"><a href="#replication/streaming">
Streaming Replication
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
20
</div><div class="section1-toc-title"><a href="#async-archiving">
Asynchronous Archiving
</a></div><div class="section2-toc"><div class="section2-toc-number">
20.1
</div><div class="section2-toc-title"><a href="#async-archiving/async-archive-push">
Archive Push
</a></div></div><div class="section2-toc"><div class="section2-toc-number">
20.2
</div><div class="section2-toc-title"><a href="#async-archiving/async-archive-get">
Archive Get
</a></div></div></div><div class="section1-toc"><div class="section1-toc-number">
21
</div><div class="section1-toc-title"><a href="#standby-backup">
Backup from a Standby
</a></div></div><div class="section1-toc"><div class="section1-toc-number">
22
</div><div class="section1-toc-title"><a href="#upgrade-stanza">
Upgrading <span class="postgres">PostgreSQL</span>
</a></div></div></div></div><div class="page-body"><div class="section1"><a id="introduction"></a><div class="section1-header"><div class="section1-number">
1
</div><div class="section1-title">
Introduction
</div></div><div class="section-body"><div class="section-body-text">
This user guide is intended to be followed sequentially from beginning to end — each section depends on the last. For example, the <a href="#restore">Restore</a> section relies on setup that is performed in the <a href="#quickstart">Quick Start</a> section. Once <span class="backrest">pgBackRest</span> is up and running then skipping around is possible but following the user guide in order is recommended the first time through.
</div><div class="section-body-text">
Although the examples are targeted at RHEL 7-8 and <span class="postgres">PostgreSQL</span> 9.6-11, it should be fairly easy to apply this guide to any Unix distribution and <span class="postgres">PostgreSQL</span> version. The only OS-specific commands are those to create, start, stop, and drop <span class="postgres">PostgreSQL</span> clusters. The <span class="backrest">pgBackRest</span> commands will be the same on any Unix system though the location to install the executable may vary.
</div><div class="section-body-text">
Configuration information and documentation for PostgreSQL can be found in the <span class="postgres">PostgreSQL</span> <a href="http://www.postgresql.org/docs/10/static/index.html">Manual</a>.
</div><div class="section-body-text">
A somewhat novel approach is taken to documentation in this user guide. Each command is run on a virtual machine when the documentation is built from the XML source. This means you can have a high confidence that the commands work correctly in the order presented. Output is captured and displayed below the command when appropriate. If the output is not included it is because it was deemed not relevant or was considered a distraction from the narrative.
</div><div class="section-body-text">
All commands are intended to be run as an unprivileged user that has sudo privileges for both the <span class="user">root</span> and <span class="user">postgres</span> users. It's also possible to run the commands directly as their respective users without modification and in that case the <span class="cmd">sudo</span> commands can be stripped off.
</div></div></div><div class="section1"><a id="concept"></a><div class="section1-header"><div class="section1-number">
2
</div><div class="section1-title">
Concepts
</div></div><div class="section-body"><div class="section-body-text">
The following concepts are defined as they are relevant to <span class="backrest">pgBackRest</span>, <span class="postgres">PostgreSQL</span>, and this user guide.
</div><div class="section2"><a id="concept/backup"></a><div class="section2-header"><div class="section2-number">
2.1
</div><div class="section2-title">
Backup
</div></div><div class="section-body"><div class="section-body-text">
A backup is a consistent copy of a database cluster that can be restored to recover from a hardware failure, to perform Point-In-Time Recovery, or to bring up a new standby.
</div><div class="section-body-text">
<b>Full Backup</b>: <span class="backrest">pgBackRest</span> copies the entire contents of the database cluster to the backup. The first backup of the database cluster is always a Full Backup. <span class="backrest">pgBackRest</span> is always able to restore a full backup directly. The full backup does not depend on any files outside of the full backup for consistency.
</div><div class="section-body-text">
<b>Differential Backup</b>: <span class="backrest">pgBackRest</span> copies only those database cluster files that have changed since the last full backup. <span class="backrest">pgBackRest</span> restores a differential backup by copying all of the files in the chosen differential backup and the appropriate unchanged files from the previous full backup. The advantage of a differential backup is that it requires less disk space than a full backup, however, the differential backup and the full backup must both be valid to restore the differential backup.
</div><div class="section-body-text">
<b>Incremental Backup</b>: <span class="backrest">pgBackRest</span> copies only those database cluster files that have changed since the last backup (which can be another incremental backup, a differential backup, or a full backup). As an incremental backup only includes those files changed since the prior backup, they are generally much smaller than full or differential backups. As with the differential backup, the incremental backup depends on other backups to be valid to restore the incremental backup. Since the incremental backup includes only those files since the last backup, all prior incremental backups back to the prior differential, the prior differential backup, and the prior full backup must all be valid to perform a restore of the incremental backup. If no differential backup exists then all prior incremental backups back to the prior full backup, which must exist, and the full backup itself must be valid to restore the incremental backup.
</div></div></div><div class="section2"><a id="concept/restore"></a><div class="section2-header"><div class="section2-number">
2.2
</div><div class="section2-title">
Restore
</div></div><div class="section-body"><div class="section-body-text">
A restore is the act of copying a backup to a system where it will be started as a live database cluster. A restore requires the backup files and one or more WAL segments in order to work correctly.
</div></div></div><div class="section2"><a id="concept/wal"></a><div class="section2-header"><div class="section2-number">
2.3
</div><div class="section2-title">
Write Ahead Log (WAL)
</div></div><div class="section-body"><div class="section-body-text">
WAL is the mechanism that <span class="postgres">PostgreSQL</span> uses to ensure that no committed changes are lost. Transactions are written sequentially to the WAL and a transaction is considered to be committed when those writes are flushed to disk. Afterwards, a background process writes the changes into the main database cluster files (also known as the heap). In the event of a crash, the WAL is replayed to make the database consistent.
</div><div class="section-body-text">
WAL is conceptually infinite but in practice is broken up into individual 16MB files called segments. WAL segments follow the naming convention <span class="id">0000000100000A1E000000FE</span> where the first 8 hexadecimal digits represent the timeline and the next 16 digits are the logical sequence number (LSN).
</div></div></div><div class="section2"><a id="concept/encryption"></a><div class="section2-header"><div class="section2-number">
2.4
</div><div class="section2-title">
Encryption
</div></div><div class="section-body"><div class="section-body-text">
Encryption is the process of converting data into a format that is unrecognizable unless the appropriate password (also referred to as passphrase) is provided.
</div><div class="section-body-text">
<span class="backrest">pgBackRest</span> will encrypt the repository based on a user-provided password, thereby preventing unauthorized access to data stored within the repository.
</div></div></div></div></div><div class="section1"><a id="upgrading"></a><div class="section1-header"><div class="section1-number">
3
</div><div class="section1-title">
Upgrading pgBackRest
</div></div><div class="section-body"><div class="section2"><a id="upgrading/v1-v2"></a><div class="section2-header"><div class="section2-number">
3.1
</div><div class="section2-title">
Upgrading pgBackRest from v1 to v2
</div></div><div class="section-body"><div class="section-body-text">
Upgrading from <span class="host">v1</span> to <span class="host">v2</span> is fairly straight-forward. The repository format has not changed and all non-deprecated options from <span class="host">v1</span> are accepted, so for most installations it is simply a matter of installing the new version.
</div><div class="section-body-text">
However, there are a few caveats:
</div><ul class="list-unordered"><li class="list-unordered">
The deprecated <span class="br-option">thread-max</span> option is no longer valid. Use <span class="br-option">process-max</span> instead.
</li><li class="list-unordered">
The deprecated <span class="br-option">archive-max-mb</span> option is no longer valid. This has been replaced with the <span class="br-option">archive-push-queue-max</span> option which has different semantics.
</li><li class="list-unordered">
The default for the <span class="br-option">backup-user</span> option has changed from <span class="id">backrest</span> to <span class="id">pgbackrest</span>.
</li><li class="list-unordered">
In <span class="host">v2.02</span> the default location of the <span class="backrest">pgBackRest</span> configuration file has changed from <span class="file">/etc/pgbackrest.conf</span> to <span class="file">/etc/pgbackrest/pgbackrest.conf</span>. If <span class="file">/etc/pgbackrest/pgbackrest.conf</span> does not exist, the <span class="file">/etc/pgbackrest.conf</span> file will be loaded instead, if it exists.
</li></ul><div class="section-body-text">
Many option names have changed to improve consistency although the old names from <span class="host">v1</span> are still accepted. In general, <span class="id">db-*</span> options have been renamed to <span class="id">pg-*</span> and <span class="id">backup-*</span>/<span class="id">retention-*</span> options have been renamed to <span class="id">repo-*</span> when appropriate.
</div><div class="section-body-text">
<span class="postgres">PostgreSQL</span> and repository options must be indexed when using the new names introduced in <span class="host">v2</span>, e.g. <span class="br-option">pg1-host</span>, <span class="br-option">pg1-path</span>, <span class="br-option">repo1-path</span>, <span class="br-option">repo1-type</span>, etc.
</div></div></div></div></div><div class="section1"><a id="build"></a><div class="section1-header"><div class="section1-number">
4
</div><div class="section1-title">
Build
</div></div><div class="section-body"><div class="section-body-text">
RHEL 7-8 packages for <span class="backrest">pgBackRest</span> are available from <a href="http://www.crunchydata.com">Crunchy Data</a> or <a href="http://yum.postgresql.org">yum.postgresql.org</a>, but it is also easy to download the source and install manually.
</div><div class="section-body-text">
When building from source it is best to use a build host rather than building on production. Many of the tools required for the build should generally not be installed in production. <span class="backrest">pgBackRest</span> consists of a single executable so it is easy to copy to a new host once it is built.
</div><div class="execute"><div class="execute-title">
<span class="host">build</span> <b>⇒</b> Download version <span class="id">2.38</span> of <span class="backrest">pgBackRest</span> to <span class="path">/build</span> path
</div><div class="execute-body">
<pre class="execute-body-cmd">mkdir -p /build</pre>
<pre class="execute-body-cmd">wget -q -O - \
https://github.com/pgbackrest/pgbackrest/archive/release/2.38.tar.gz | \
tar zx -C /build</pre>
</div></div><div class="execute"><div class="execute-title">
<span class="host">build</span> <b>⇒</b> Install build dependencies
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo yum install make gcc postgresql10-devel \
openssl-devel libxml2-devel lz4-devel libzstd-devel bzip2-devel libyaml-devel</pre>
</div></div><div class="execute"><div class="execute-title">
<span class="host">build</span> <b>⇒</b> Configure and compile <span class="backrest">pgBackRest</span>
</div><div class="execute-body">
<pre class="execute-body-cmd">cd /build/pgbackrest-release-2.38/src && ./configure && make</pre>
</div></div></div></div><div class="section1"><a id="installation"></a><div class="section1-header"><div class="section1-number">
5
</div><div class="section1-title">
Installation
</div></div><div class="section-body"><div class="section-body-text">
A new host named <span class="host">pg-primary</span> is created to contain the demo cluster and run <span class="backrest">pgBackRest</span> examples.
</div><div class="section-body-text">
<span class="backrest">pgBackRest</span> needs to be installed from a package or installed manually as shown here.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Install dependencies
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo yum install postgresql-libs</pre>
</div></div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Copy <span class="backrest">pgBackRest</span> binary from build host
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo scp build:/build/pgbackrest-release-2.38/src/pgbackrest /usr/bin</pre>
<pre class="execute-body-cmd">sudo chmod 755 /usr/bin/pgbackrest</pre>
</div></div><div class="section-body-text">
<span class="backrest">pgBackRest</span> requires log and configuration directories and a configuration file.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Create <span class="backrest">pgBackRest</span> configuration file and directories
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo mkdir -p -m 770 /var/log/pgbackrest</pre>
<pre class="execute-body-cmd">sudo chown postgres:postgres /var/log/pgbackrest</pre>
<pre class="execute-body-cmd">sudo mkdir -p /etc/pgbackrest</pre>
<pre class="execute-body-cmd">sudo mkdir -p /etc/pgbackrest/conf.d</pre>
<pre class="execute-body-cmd">sudo touch /etc/pgbackrest/pgbackrest.conf</pre>
<pre class="execute-body-cmd">sudo chmod 640 /etc/pgbackrest/pgbackrest.conf</pre>
<pre class="execute-body-cmd">sudo chown postgres:postgres /etc/pgbackrest/pgbackrest.conf</pre>
</div></div><div class="section-body-text">
<span class="backrest">pgBackRest</span> should now be properly installed but it is best to check. If any dependencies were missed then you will get an error when running <span class="backrest">pgBackRest</span> from the command line.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Make sure the installation worked
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest</pre>
<pre class="execute-body-output">pgBackRest 2.38 - General help
Usage:
pgbackrest [options] [command]
Commands:
archive-get Get a WAL segment from the archive.
archive-push Push a WAL segment to the archive.
backup Backup a database cluster.
check Check the configuration.
expire Expire backups that exceed retention.
help Get help.
info Retrieve information about backups.
repo-get Get a file from a repository.
repo-ls List files in a repository.
restore Restore a database cluster.
server pgBackRest server.
server-ping Ping pgBackRest server.
stanza-create Create the required stanza data.
stanza-delete Delete a stanza.
stanza-upgrade Upgrade a stanza.
start Allow pgBackRest processes to run.
stop Stop pgBackRest processes from running.
version Get version.
Use 'pgbackrest help [command]' for more information.</pre>
</div></div></div></div><div class="section1"><a id="quickstart"></a><div class="section1-header"><div class="section1-number">
6
</div><div class="section1-title">
Quick Start
</div></div><div class="section-body"><div class="section-body-text">
The Quick Start section will cover basic configuration of <span class="backrest">pgBackRest</span> and <span class="postgres">PostgreSQL</span> and introduce the <span class="cmd">backup</span>, <span class="cmd">restore</span>, and <span class="cmd">info</span> commands.
</div><div class="section2"><a id="quickstart/setup-demo-cluster"></a><div class="section2-header"><div class="section2-number">
6.1
</div><div class="section2-title">
Setup Demo Cluster
</div></div><div class="section-body"><div class="section-body-text">
Creating the demo cluster is optional but is strongly recommended, especially for new users, since the example commands in the user guide reference the demo cluster; the examples assume the demo cluster is running on the default port (i.e. 5432). The cluster will not be started until a later section because there is still some configuration to do.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Create the demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres /usr/pgsql-10/bin/initdb \
-D /var/lib/pgsql/10/data -k -A peer</pre>
</div></div><div class="section-body-text">
By default RHEL 7-8 includes the day of the week in the log filename. This makes the user guide a bit more complicated so the <span class="pg-option">log_filename</span> is set to a constant.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/var/lib/pgsql/10/data/postgresql.conf</span> <b>⇒</b> Set <span class="pg-option">log_filename</span>
</div><div class="config-body"><div class="config-body-output">
log_filename = 'postgresql.log'
</div></div></div></div></div><div class="section2"><a id="quickstart/configure-stanza"></a><div class="section2-header"><div class="section2-number">
6.2
</div><div class="section2-title">
Configure Cluster Stanza
</div></div><div class="section-body"><div class="section-body-text">
A stanza is the configuration for a <span class="postgres">PostgreSQL</span> 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.<br/>
<br/>
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.
</div><div class="section-body-text">
The name 'demo' describes the purpose of this cluster accurately so that will also make a good stanza name.
</div><div class="section-body-text">
<span class="backrest">pgBackRest</span> needs to know where the base data directory for the <span class="postgres">PostgreSQL</span> cluster is located. The path can be requested from <span class="postgres">PostgreSQL</span> directly but in a recovery scenario the <span class="postgres">PostgreSQL</span> process will not be available. During backups the value supplied to <span class="backrest">pgBackRest</span> will be compared against the path that <span class="postgres">PostgreSQL</span> is running on and they must be equal or the backup will return an error. Make sure that <span class="br-option">pg-path</span> is exactly equal to <span class="pg-option">data_directory</span> in <span class="file">postgresql.conf</span>.
</div><div class="section-body-text">
By default RHEL 7-8 stores clusters in <span class="path">/var/lib/pgsql/[version]/data</span> so it is easy to determine the correct path for the data directory.
</div><div class="section-body-text">
When creating the <span class="file">/etc/pgbackrest/pgbackrest.conf</span> file, the database owner (usually <span class="id">postgres</span>) must be granted read privileges.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure the <span class="postgres">PostgreSQL</span> cluster data directory
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data
</div></div></div><div class="section-body-text">
<span class="backrest">pgBackRest</span> configuration files follow the Windows INI convention. Sections are denoted by text in brackets and key/value pairs are contained in each section. Lines beginning with <span class="id">#</span> are ignored and can be used as comments.
</div><div class="section-body-text">
There are multiple ways the <span class="backrest">pgBackRest</span> configuration files can be loaded:
</div><ul class="list-unordered"><li class="list-unordered">
<span class="br-option">config</span> and <span class="br-option">config-include-path</span> are default: the default config file will be loaded, if it exists, and <span class="file">*.conf</span> files in the default config include path will be appended, if they exist.
</li><li class="list-unordered">
<span class="br-option">config</span> option is specified: only the specified config file will be loaded and is expected to exist.
</li><li class="list-unordered">
<span class="br-option">config-include-path</span> is specified: <span class="file">*.conf</span> files in the config include path will be loaded and the path is required to exist. The default config file will be be loaded if it exists. If it is desirable to load only the files in the specified config include path, then the <span class="br-option">--no-config</span> option can also be passed.
</li><li class="list-unordered">
<span class="br-option">config</span> and <span class="br-option">config-include-path</span> are specified: using the user-specified values, the config file will be loaded and <span class="file">*.conf</span> files in the config include path will be appended. The files are expected to exist.
</li><li class="list-unordered">
<span class="br-option">config-path</span> is specified: this setting will override the base path for the default location of the config file and/or the base path of the default config-include-path setting unless the config and/or config-include-path option is explicitly set.
</li></ul><div class="section-body-text">
The files are concatenated as if they were one big file; order doesn't matter, but there is precedence based on sections. The precedence (highest to lowest) is:
</div><ul class="list-unordered"><li class="list-unordered">
[<i>stanza</i>:<i>command</i>]
</li><li class="list-unordered">
[<i>stanza</i>]
</li><li class="list-unordered">
[global:<i>command</i>]
</li><li class="list-unordered">
[global]
</li></ul><div class="admonition"><div class="note">
NOTE:
</div><div class="note-text">
<span class="br-option">--config</span>, <span class="br-option">--config-include-path</span> and <span class="br-option">--config-path</span> are command-line only options.
</div></div><div class="section-body-text">
<span class="backrest">pgBackRest</span> can also be configured using environment variables as described in the <a href="command.html">command reference</a>.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Configure <span class="br-option">log-path</span> using the environment
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres bash -c ' \
export PGBACKREST_LOG_PATH=/path/set/by/env && \
pgbackrest --log-level-console=error help backup log-path'</pre>
<pre class="execute-body-output">pgBackRest 2.38 - 'backup' command - 'log-path' option help
Path where log files are stored.
The log path provides a location for pgBackRest to store log files. Note that
if log-level-file=off then no log path is required.
</pre>
<pre class="execute-body-output-highlight">current: /path/set/by/env</pre>
<pre class="execute-body-output">default: /var/log/pgbackrest</pre>
</div></div></div></div><div class="section2"><a id="quickstart/create-repository"></a><div class="section2-header"><div class="section2-number">
6.3
</div><div class="section2-title">
Create the Repository
</div></div><div class="section-body"><div class="section-body-text">
The repository is where <span class="backrest">pgBackRest</span> stores backups and archives WAL segments.<br/>
<br/>
It may 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.
</div><div class="section-body-text">
For this demonstration the repository will be stored on the same host as the <span class="postgres">PostgreSQL</span> server. This is the simplest configuration and is useful in cases where traditional backup software is employed to backup the database host.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Create the <span class="backrest">pgBackRest</span> repository
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo mkdir -p /var/lib/pgbackrest</pre>
<pre class="execute-body-cmd">sudo chmod 750 /var/lib/pgbackrest</pre>
<pre class="execute-body-cmd">sudo chown postgres:postgres /var/lib/pgbackrest</pre>
</div></div><div class="section-body-text">
The repository path must be configured so <span class="backrest">pgBackRest</span> knows where to find it.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure the <span class="backrest">pgBackRest</span> repository path
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-path=/var/lib/pgbackrest
</div></div></div><div class="section-body-text">
Multiple repositories may also be configured. See <a href="#multi-repo">Multiple Repositories</a> for details.
</div></div></div><div class="section2"><a id="quickstart/configure-archiving"></a><div class="section2-header"><div class="section2-number">
6.4
</div><div class="section2-title">
Configure Archiving
</div></div><div class="section-body"><div class="section-body-text">
Backing up a running <span class="postgres">PostgreSQL</span> cluster requires WAL archiving to be enabled. Note that <i>at least</i> one WAL segment will be created during the backup process even if no explicit writes are made to the cluster.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/var/lib/pgsql/10/data/postgresql.conf</span> <b>⇒</b> Configure archive settings
</div><div class="config-body"><div class="config-body-output">
archive_command = 'pgbackrest --stanza=demo archive-push %p'<br/>
archive_mode = on<br/>
log_filename = 'postgresql.log'<br/>
max_wal_senders = 3<br/>
wal_level = replica
</div></div></div><div class="section-body-text">
<span class="id">%p</span> is how <span class="postgres">PostgreSQL</span> specifies the location of the WAL segment to be archived. Setting <span class="pg-option">wal_level</span> to at least <span class="pg-setting">replica</span> and increasing <span class="pg-option">max_wal_senders</span> is a good idea even if there are currently no replicas as this will allow them to be added later without restarting the primary cluster.
</div><div class="section-body-text">
The <span class="postgres">PostgreSQL</span> cluster must be restarted after making these changes and before performing a backup.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Restart the demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo systemctl restart postgresql-10.service</pre>
</div></div><div class="section-body-text">
When archiving a WAL segment is expected to take more than 60 seconds (the default) to reach the <span class="backrest">pgBackRest</span> repository, then the <span class="backrest">pgBackRest</span> <span class="br-option">archive-timeout</span> option should be increased. Note that this option is not the same as the <span class="postgres">PostgreSQL</span> <span class="pg-option">archive_timeout</span> option which is used to force a WAL segment switch; useful for databases where there are long periods of inactivity. For more information on the <span class="postgres">PostgreSQL</span> <span class="pg-option">archive_timeout</span> option, see <span class="postgres">PostgreSQL</span> <a href="https://www.postgresql.org/docs/current/static/runtime-config-wal.html">Write Ahead Log</a>.
</div><div class="section-body-text">
The <span class="cmd">archive-push</span> command can be configured with its own options. For example, a lower compression level may be set to speed archiving without affecting the compression used for backups.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Config <span class="cmd">archive-push</span> to use a lower compression level
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-path=/var/lib/pgbackrest<br/>
<br/>
[global:archive-push]<br/>
compress-level=3
</div></div></div><div class="section-body-text">
This configuration technique can be used for any command and can even target a specific stanza, e.g. <span class="id">demo:archive-push</span>.
</div></div></div><div class="section2"><a id="quickstart/retention"></a><div class="section2-header"><div class="section2-number">
6.5
</div><div class="section2-title">
Configure Retention
</div></div><div class="section-body"><div class="section-body-text">
<span class="backrest">pgBackRest</span> expires backups based on retention options.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure retention to 2 full backups
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-path=/var/lib/pgbackrest<br/>
repo1-retention-full=2<br/>
<br/>
[global:archive-push]<br/>
compress-level=3
</div></div></div><div class="section-body-text">
More information about retention can be found in the <a href="#retention">Retention</a> section.
</div></div></div><div class="section2"><a id="quickstart/configure-encryption"></a><div class="section2-header"><div class="section2-number">
6.6
</div><div class="section2-title">
Configure Repository Encryption
</div></div><div class="section-body"><div class="section-body-text">
The repository will be configured with a cipher type and key to demonstrate encryption. Encryption is always performed client-side even if the repository type (e.g. <span class="host">S3</span> or other object store) supports encryption.
</div><div class="section-body-text">
It is important to use a long, random passphrase for the cipher key. A good way to generate one is to run: <span class="id">openssl rand -base64 48</span>.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure <span class="backrest">pgBackRest</span> repository encryption
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-cipher-pass=zWaf6XtpjIVZC5444yXB+cgFDFl7MxGlgkZSaoPvTGirhPygu4jOKOXf9LO4vjfO<br/>
repo1-cipher-type=aes-256-cbc<br/>
repo1-path=/var/lib/pgbackrest<br/>
repo1-retention-full=2<br/>
<br/>
[global:archive-push]<br/>
compress-level=3
</div></div></div><div class="section-body-text">
Once the repository has been configured and the stanza created and checked, the repository encryption settings cannot be changed.
</div></div></div><div class="section2"><a id="quickstart/create-stanza"></a><div class="section2-header"><div class="section2-number">
6.7
</div><div class="section2-title">
Create the Stanza
</div></div><div class="section-body"><div class="section-body-text">
The <span class="cmd">stanza-create</span> command must be run to initialize the stanza. It is recommended that the <span class="cmd">check</span> command be run after <span class="cmd">stanza-create</span> to ensure archiving and backups are properly configured.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Create the stanza and check the configuration
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --log-level-console=info stanza-create</pre>
<pre class="execute-body-output">P00 INFO: stanza-create command begin 2.38: --exec-id=1105-a5f9af42 --log-level-console=info --log-level-stderr=off --no-log-timestamp --pg1-path=/var/lib/pgsql/10/data --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --stanza=demo
P00 INFO: stanza-create for stanza 'demo' on repo1</pre>
<pre class="execute-body-output-highlight">P00 INFO: stanza-create command end: completed successfully</pre>
</div></div></div></div><div class="section2"><a id="quickstart/check-configuration"></a><div class="section2-header"><div class="section2-number">
6.8
</div><div class="section2-title">
Check the Configuration
</div></div><div class="section-body"><div class="section-body-text">
The <span class="cmd">check</span> command validates that <span class="backrest">pgBackRest</span> and the <span class="pg-setting">archive_command</span> setting are configured correctly for archiving and backups for the specified stanza. It will attempt to check all repositories and databases that are configured for the host on which the command is run. It detects misconfigurations, particularly in archiving, that result in incomplete backups because required WAL segments did not reach the archive. The command can be run on the <span class="postgres">PostgreSQL</span> or repository host. The command may also be run on the standby host, however, since <span class="id">pg_switch_xlog()</span>/<span class="id">pg_switch_wal()</span> cannot be performed on the standby, the command will only test the repository configuration.<br/>
<br/>
Note that <span class="id">pg_create_restore_point('pgBackRest Archive Check')</span> and <span class="id">pg_switch_xlog()</span>/<span class="id">pg_switch_wal()</span> are called to force <span class="postgres">PostgreSQL</span> to archive a WAL segment. Restore points are only supported in <span class="postgres">PostgreSQL</span> >= 9.1 so for older versions the <span class="cmd">check</span> command may fail if there has been no write activity since the last log rotation, therefore it is recommended that activity be generated by the user if there have been no writes since the last WAL switch before running the <span class="cmd">check</span> command.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Check the configuration
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --log-level-console=info check</pre>
<pre class="execute-body-output">P00 INFO: check command begin 2.38: --exec-id=1132-6eb7c46d --log-level-console=info --log-level-stderr=off --no-log-timestamp --pg1-path=/var/lib/pgsql/10/data --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --stanza=demo
P00 INFO: check repo1 configuration (primary)
P00 INFO: check repo1 archive for WAL (primary)</pre>
<pre class="execute-body-output-highlight">P00 INFO: WAL segment 000000010000000000000001 successfully archived to '/var/lib/pgbackrest/archive/demo/10-1/0000000100000000/000000010000000000000001-c1880edf6b0208ff8529a5bbcf0c7a0f95727017.gz' on repo1</pre>
<pre class="execute-body-output">P00 INFO: check command end: completed successfully</pre>
</div></div></div></div><div class="section2"><a id="quickstart/perform-backup"></a><div class="section2-header"><div class="section2-number">
6.9
</div><div class="section2-title">
Perform a Backup
</div></div><div class="section-body"><div class="section-body-text">
By default <span class="backrest">pgBackRest</span> will wait for the next regularly scheduled checkpoint before starting a backup. Depending on the <span class="pg-option">checkpoint_timeout</span> and <span class="pg-option">checkpoint_segments</span> settings in <span class="postgres">PostgreSQL</span> it may be quite some time before a checkpoint completes and the backup can begin. Generally, it is best to set <span class="br-setting">start-fast=y</span> so that the backup starts immediately. This forces a checkpoint, but since backups are usually run once a day an additional checkpoint should not have a noticeable impact on performance. However, on very busy clusters it may be best to pass <span class="br-setting">--start-fast</span> on the command-line as needed.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure backup fast start
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-cipher-pass=zWaf6XtpjIVZC5444yXB+cgFDFl7MxGlgkZSaoPvTGirhPygu4jOKOXf9LO4vjfO<br/>
repo1-cipher-type=aes-256-cbc<br/>
repo1-path=/var/lib/pgbackrest<br/>
repo1-retention-full=2<br/>
start-fast=y<br/>
<br/>
[global:archive-push]<br/>
compress-level=3
</div></div></div><div class="section-body-text">
To perform a backup of the <span class="postgres">PostgreSQL</span> cluster run <span class="backrest">pgBackRest</span> with the <span class="cmd">backup</span> command.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Backup the demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo \
--log-level-console=info backup</pre>
<pre class="execute-body-output">P00 INFO: backup command begin 2.38: --exec-id=1203-108e58c4 --log-level-console=info --log-level-stderr=off --no-log-timestamp --pg1-path=/var/lib/pgsql/10/data --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-full=2 --stanza=demo --start-fast</pre>
<pre class="execute-body-output-highlight">P00 WARN: no prior backup exists, incr backup has been changed to full</pre>
<pre class="execute-body-output">P00 INFO: execute non-exclusive pg_start_backup(): backup begins after the requested immediate checkpoint completes
P00 INFO: backup start archive = 000000010000000000000002, lsn = 0/2000028
[filtered 3 lines of output]
P00 INFO: check archive for segment(s) 000000010000000000000002:000000010000000000000003
P00 INFO: new backup label = 20220306-154349F</pre>
<pre class="execute-body-output-highlight">P00 INFO: full backup size = 22.5MB, file total = 949</pre>
<pre class="execute-body-output">P00 INFO: backup command end: completed successfully
P00 INFO: expire command begin 2.38: --exec-id=1203-108e58c4 --log-level-console=info --log-level-stderr=off --no-log-timestamp --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-full=2 --stanza=demo</pre>
</div></div><div class="section-body-text">
By default <span class="backrest">pgBackRest</span> will attempt to perform an incremental backup. However, an incremental backup must be based on a full backup and since no full backup existed <span class="backrest">pgBackRest</span> ran a full backup instead.
</div><div class="section-body-text">
The <span class="br-option">type</span> option can be used to specify a full or differential backup.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Differential backup of the demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --type=diff \
--log-level-console=info backup</pre>
<pre class="execute-body-output"> [filtered 7 lines of output]
P00 INFO: check archive for segment(s) 000000010000000000000004:000000010000000000000005
P00 INFO: new backup label = 20220306-154349F_20220306-154353D</pre>
<pre class="execute-body-output-highlight">P00 INFO: diff backup size = 8.8KB, file total = 949</pre>
<pre class="execute-body-output">P00 INFO: backup command end: completed successfully
P00 INFO: expire command begin 2.38: --exec-id=1263-4805fd6a --log-level-console=info --log-level-stderr=off --no-log-timestamp --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-full=2 --stanza=demo</pre>
</div></div><div class="section-body-text">
This time there was no warning because a full backup already existed. While incremental backups can be based on a full <i>or</i> differential backup, differential backups must be based on a full backup. A full backup can be performed by running the <span class="cmd">backup</span> command with <span class="br-setting">--type=full</span>.
</div><div class="section-body-text">
During an online backup <span class="backrest">pgBackRest</span> waits for WAL segments that are required for backup consistency to be archived. This wait time is governed by the <span class="backrest">pgBackRest</span> <span class="br-option">archive-timeout</span> option which defaults to 60 seconds. If archiving an individual segment is known to take longer then this option should be increased.
</div></div></div><div class="section2"><a id="quickstart/schedule-backup"></a><div class="section2-header"><div class="section2-number">
6.10
</div><div class="section2-title">
Schedule a Backup
</div></div><div class="section-body"><div class="section-body-text">
Backups can be scheduled with utilities such as cron.
</div><div class="section-body-text">
In the following example, two cron jobs are configured to run; full backups are scheduled for 6:30 AM every Sunday with differential backups scheduled for 6:30 AM Monday through Saturday. If this crontab is installed for the first time mid-week, then pgBackRest will run a full backup the first time the differential job is executed, followed the next day by a differential backup.
</div>
<pre class="code-block">#m h dom mon dow command
30 06 * * 0 pgbackrest --type=full --stanza=demo backup
30 06 * * 1-6 pgbackrest --type=diff --stanza=demo backup</pre>
<div class="section-body-text">
Once backups are scheduled it's important to configure retention so backups are expired on a regular schedule, see <a href="#retention">Retention</a>.
</div></div></div><div class="section2"><a id="quickstart/backup-info"></a><div class="section2-header"><div class="section2-number">
6.11
</div><div class="section2-title">
Backup Information
</div></div><div class="section-body"><div class="section-body-text">
Use the <span class="cmd">info</span> command to get information about backups.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Get info for the demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest info</pre>
<pre class="execute-body-output">stanza: demo
status: ok
cipher: aes-256-cbc
db (current)
wal archive min/max (10): 000000010000000000000001/000000010000000000000005
</pre>
<pre class="execute-body-output-highlight"> full backup: 20220306-154349F</pre>
<pre class="execute-body-output"> timestamp start/stop: 2022-03-06 15:43:49 / 2022-03-06 15:43:52
wal start/stop: 000000010000000000000002 / 000000010000000000000003
database size: 22.5MB, database backup size: 22.5MB
repo1: backup set size: 2.7MB, backup size: 2.7MB
</pre>
<pre class="execute-body-output-highlight"> diff backup: 20220306-154349F_20220306-154353D</pre>
<pre class="execute-body-output"> timestamp start/stop: 2022-03-06 15:43:53 / 2022-03-06 15:43:55
wal start/stop: 000000010000000000000004 / 000000010000000000000005
database size: 22.5MB, database backup size: 8.8KB
repo1: backup set size: 2.7MB, backup size: 752B
backup reference list: 20220306-154349F</pre>
</div></div><div class="section-body-text">
The <span class="cmd">info</span> 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.<br/>
<br/>
For machine-readable output use <span class="br-option">--output=json</span>. The JSON output contains far more information than the text output and is kept stable unless a bug is found.<br/>
<br/>
Each stanza has a separate section and it is possible to limit output to a single stanza with the <span class="br-option">--stanza</span> option. The stanza '<span class="id">status</span>' gives a brief indication of the stanza's health. If this is '<span class="id">ok</span>' then <span class="backrest">pgBackRest</span> is functioning normally. If there are multiple repositories, then a status of '<span class="id">mixed</span>' indicates that the stanza is not in a healthy state on one or more of the repositories; in this case the state of the stanza will be detailed per repository. For cases in which an error on a repository occurred that is not one of the known error codes, then an error code of '<span class="id">other</span>' will be used and the full error details will be provided. The '<span class="id">wal archive min/max</span>' shows the minimum and maximum WAL currently stored in the archive and, in the case of multiple repositories, will be reported across all repositories unless the <span class="br-option">--repo</span> option is set. Note that there may be gaps due to archive retention policies or other reasons.<br/>
<br/>
The '<span class="id">backup/expire running</span>' message will appear beside the '<span class="id">status</span>' information if one of those commands is currently running on the host.<br/>
<br/>
The backups are displayed oldest to newest. The oldest backup will <i>always</i> be a full backup (indicated by an <span class="id">F</span> at the end of the label) but the newest backup can be full, differential (ends with <span class="id">D</span>), or incremental (ends with <span class="id">I</span>).<br/>
<br/>
The '<span class="id">timestamp start/stop</span>' defines the time period when the backup ran. The '<span class="id">timestamp stop</span>' can be used to determine the backup to use when performing Point-In-Time Recovery. More information about Point-In-Time Recovery can be found in the <a href="#pitr">Point-In-Time Recovery</a> section.<br/>
<br/>
The '<span class="id">wal start/stop</span>' defines the WAL range that is required to make the database consistent when restoring. The <span class="cmd">backup</span> command will ensure that this WAL range is in the archive before completing.<br/>
<br/>
The '<span class="id">database size</span>' is the full uncompressed size of the database while '<span class="id">database backup size</span>' is the amount of data in the database to actually back up (these will be the same for full backups).<br/>
<br/>
The '<span class="id">repo</span>' indicates in which repository this backup resides. The '<span class="id">backup set size</span>' includes all the files from this backup and any referenced backups in the repository that are required to restore the database from this backup while '<span class="id">backup size</span>' includes only the files in this backup (these will also be the same for full backups). Repository sizes reflect compressed file sizes if compression is enabled in <span class="backrest">pgBackRest</span>.<br/>
<br/>
The '<span class="id">backup reference list</span>' contains the additional backups that are required to restore this backup.
</div></div></div><div class="section2"><a id="quickstart/perform-restore"></a><div class="section2-header"><div class="section2-number">
6.12
</div><div class="section2-title">
Restore a Backup
</div></div><div class="section-body"><div class="section-body-text">
Backups can protect you from a number of disaster scenarios, the most common of which are hardware failure and data corruption. The easiest way to simulate data corruption is to remove an important <span class="postgres">PostgreSQL</span> cluster file.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Stop the demo cluster and delete the <span class="file">pg_control</span> file
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo systemctl stop postgresql-10.service</pre>
<pre class="execute-body-cmd">sudo -u postgres rm /var/lib/pgsql/10/data/global/pg_control</pre>
</div></div><div class="section-body-text">
Starting the cluster without this important file will result in an error.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Attempt to start the corrupted demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo systemctl start postgresql-10.service</pre>
<pre class="execute-body-cmd">sudo systemctl status postgresql-10.service</pre>
<pre class="execute-body-output"> [filtered 12 lines of output]
Mar 06 15:43:56 pg-primary systemd[1]: postgresql-10.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
Mar 06 15:43:56 pg-primary systemd[1]: postgresql-10.service: Failed with result 'exit-code'.</pre>
<pre class="execute-body-output-highlight-error">Mar 06 15:43:56 pg-primary systemd[1]: Failed to start PostgreSQL 10 database server.</pre>
</div></div><div class="section-body-text">
To restore a backup of the <span class="postgres">PostgreSQL</span> cluster run <span class="backrest">pgBackRest</span> with the <span class="cmd">restore</span> command. The cluster needs to be stopped (in this case it is already stopped) and all files must be removed from the <span class="postgres">PostgreSQL</span> data directory.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Remove old files from demo cluster
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres find /var/lib/pgsql/10/data -mindepth 1 -delete</pre>
</div></div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Restore the demo cluster and start <span class="postgres">PostgreSQL</span>
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo restore</pre>
<pre class="execute-body-cmd">sudo systemctl start postgresql-10.service</pre>
</div></div><div class="section-body-text">
This time the cluster started successfully since the restore replaced the missing <span class="file">pg_control</span> file.
</div><div class="section-body-text">
More information about the <span class="cmd">restore</span> command can be found in the <a href="#restore">Restore</a> section.
</div></div></div></div></div><div class="section1"><a id="monitor"></a><div class="section1-header"><div class="section1-number">
7
</div><div class="section1-title">
Monitoring
</div></div><div class="section-body"><div class="section-body-text">
Monitoring is an important part of any production system. There are many tools available and <span class="backrest">pgBackRest</span> can be monitored on any of them with a little work.
</div><div class="section-body-text">
<span class="backrest">pgBackRest</span> can output information about the repository in JSON format which includes a list of all backups for each stanza and WAL archive info.
</div><div class="section2"><a id="monitor/postgresql"></a><div class="section2-header"><div class="section2-number">
7.1
</div><div class="section2-title">
In <span class="postgres">PostgreSQL</span>
</div></div><div class="section-body"><div class="section-body-text">
The <span class="postgres">PostgreSQL</span> <span class="id">COPY</span> command allows <span class="backrest">pgBackRest</span> info to be loaded into a table. The following example wraps that logic in a function that can be used to perform real-time queries.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Load <span class="backrest">pgBackRest</span> info function for <span class="postgres">PostgreSQL</span>
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres cat \
/var/lib/pgsql/pgbackrest/doc/example/pgsql-pgbackrest-info.sql</pre>
<pre class="execute-body-output">-- An example of monitoring pgBackRest from within PostgreSQL
--
-- Use copy to export data from the pgBackRest info command into the jsonb
-- type so it can be queried directly by PostgreSQL.
-- Create monitor schema
create schema monitor;
-- Get pgBackRest info in JSON format
create function monitor.pgbackrest_info()
returns jsonb AS $$
declare
data jsonb;
begin
-- Create a temp table to hold the JSON data
create temp table temp_pgbackrest_data (data jsonb);
-- Copy data into the table directly from the pgBackRest info command
copy temp_pgbackrest_data (data)
from program
'pgbackrest --output=json info' (format text);
select temp_pgbackrest_data.data
into data
from temp_pgbackrest_data;
drop table temp_pgbackrest_data;
return data;
end $$ language plpgsql;</pre>
<pre class="execute-body-cmd">sudo -u postgres psql -f \
/var/lib/pgsql/pgbackrest/doc/example/pgsql-pgbackrest-info.sql</pre>
</div></div><div class="section-body-text">
Now the <span class="id">monitor.pgbackrest_info()</span> function can be used to determine the last successful backup time and archived WAL for a stanza.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Query last successful backup time and archived WAL
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres cat \
/var/lib/pgsql/pgbackrest/doc/example/pgsql-pgbackrest-query.sql</pre>
<pre class="execute-body-output">-- Get last successful backup for each stanza
--
-- Requires the monitor.pgbackrest_info function.
with stanza as
(
select data->'name' as name,
data->'backup'->(
jsonb_array_length(data->'backup') - 1) as last_backup,
data->'archive'->(
jsonb_array_length(data->'archive') - 1) as current_archive
from jsonb_array_elements(monitor.pgbackrest_info()) as data
)
select name,
to_timestamp(
(last_backup->'timestamp'->>'stop')::numeric) as last_successful_backup,
current_archive->>'max' as last_archived_wal
from stanza;</pre>
<pre class="execute-body-cmd">sudo -u postgres psql -f \
/var/lib/pgsql/pgbackrest/doc/example/pgsql-pgbackrest-query.sql</pre>
<pre class="execute-body-output"> name | last_successful_backup | last_archived_wal
--------+------------------------+--------------------------
"demo" | 2022-03-06 15:43:55+00 | 000000010000000000000005
(1 row)</pre>
</div></div></div></div></div></div><div class="section1"><a id="retention"></a><div class="section1-header"><div class="section1-number">
8
</div><div class="section1-title">
Retention
</div></div><div class="section-body"><div class="section-body-text">
Generally it is best to retain as many backups as possible to provide a greater window for <a href="#pitr">Point-in-Time Recovery</a>, but practical concerns such as disk space must also be considered. Retention options remove older backups once they are no longer needed.
</div><div class="section-body-text">
<span class="backrest">pgBackRest</span> does full backup rotation based on the retention type which can be a count or a time period. When a count is specified, then expiration is not concerned with when the backups were created but with how many must be retained. Differential and Incremental backups are count-based but will always be expired when the backup they depend on is expired. See sections <a href="#retention/full">Full Backup Retention</a> and <a href="#retention/diff">Differential Backup Retention</a> for details and examples. Archived WAL is retained by default for backups that have not expired, however, although not recommended, this schedule can be modified per repository with the retention-archive options. See section <a href="#retention/archive">Archive Retention</a> for details and examples.<br/>
<br/>
The <span class="cmd">expire</span> command is run automatically after each successful backup and can also be run by the user. When run by the user, expiration will occur as defined by the retention settings for each configured repository. If the <span class="br-option">--repo</span> option is provided, expiration will occur only on the specified repository. Expiration can also be limited by the user to a specific backup set with the <span class="br-option">--set</span> option and, unless the <span class="br-option">--repo</span> option is specified, all repositories will be searched and any matching the set criteria will be expired. It should be noted that the archive retention schedule will be checked and performed any time the <span class="cmd">expire</span> command is run.
</div><div class="section2"><a id="retention/full"></a><div class="section2-header"><div class="section2-number">
8.1
</div><div class="section2-title">
Full Backup Retention
</div></div><div class="section-body"><div class="section-body-text">
The <span class="br-option">repo1-retention-full-type</span> determines how the option <span class="br-option">repo1-retention-full</span> is interpreted; either as the count of full backups to be retained or how many days to retain full backups. New backups must be completed before expiration will occur — that means if <span class="br-setting">repo1-retention-full-type=count</span> and <span class="br-setting">repo1-retention-full=2</span> then there will be three full backups stored before the oldest one is expired, or if <span class="br-setting">repo1-retention-full-type=time</span> and <span class="br-setting">repo1-retention-full=20</span> then there must be one full backup that is at least 20 days old before expiration can occur.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure <span class="br-option">repo1-retention-full</span>
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-cipher-pass=zWaf6XtpjIVZC5444yXB+cgFDFl7MxGlgkZSaoPvTGirhPygu4jOKOXf9LO4vjfO<br/>
repo1-cipher-type=aes-256-cbc<br/>
repo1-path=/var/lib/pgbackrest<br/>
repo1-retention-full=2<br/>
start-fast=y<br/>
<br/>
[global:archive-push]<br/>
compress-level=3
</div></div></div><div class="section-body-text">
Backup <span class="br-setting">repo1-retention-full=2</span> but currently there is only one full backup so the next full backup to run will not expire any full backups.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Perform a full backup
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --type=full \
--log-level-console=detail backup</pre>
<pre class="execute-body-output"> [filtered 958 lines of output]
P00 INFO: backup command end: completed successfully
P00 INFO: expire command begin 2.38: --exec-id=1767-6fe05c25 --log-level-console=detail --log-level-stderr=off --no-log-timestamp --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-full=2 --stanza=demo</pre>
<pre class="execute-body-output-highlight">P00 DETAIL: repo1: 10-1 archive retention on backup 20220306-154349F, start = 000000010000000000000002
P00 INFO: repo1: 10-1 remove archive, start = 000000010000000000000001, stop = 000000010000000000000001</pre>
<pre class="execute-body-output">P00 INFO: expire command end: completed successfully</pre>
</div></div><div class="section-body-text">
Archive <i>is</i> expired because WAL segments were generated before the oldest backup. These are not useful for recovery — only WAL segments generated after a backup can be used to recover that backup.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Perform a full backup
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --type=full \
--log-level-console=info backup</pre>
<pre class="execute-body-output"> [filtered 9 lines of output]
P00 INFO: backup command end: completed successfully
P00 INFO: expire command begin 2.38: --exec-id=1826-5340bdb7 --log-level-console=info --log-level-stderr=off --no-log-timestamp --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-full=2 --stanza=demo</pre>
<pre class="execute-body-output-highlight">P00 INFO: repo1: expire full backup set 20220306-154349F, 20220306-154349F_20220306-154353D</pre>
<pre class="execute-body-output">P00 INFO: repo1: remove expired backup 20220306-154349F_20220306-154353D
P00 INFO: repo1: remove expired backup 20220306-154349F</pre>
<pre class="execute-body-output-highlight">P00 INFO: repo1: 10-1 remove archive, start = 0000000100000000, stop = 000000020000000000000006</pre>
<pre class="execute-body-output">P00 INFO: expire command end: completed successfully</pre>
</div></div><div class="section-body-text">
The <span class="id">20220306-154349F</span> full backup is expired and archive retention is based on the <span class="id">20220306-154403F</span> which is now the oldest full backup.
</div></div></div><div class="section2"><a id="retention/diff"></a><div class="section2-header"><div class="section2-number">
8.2
</div><div class="section2-title">
Differential Backup Retention
</div></div><div class="section-body"><div class="section-body-text">
Set <span class="br-option">repo1-retention-diff</span> to the number of differential backups required. Differentials only rely on the prior full backup so it is possible to create a <q>rolling</q> set of differentials for the last day or more. This allows quick restores to recent points-in-time but reduces overall space consumption.
</div><div class="config"><div class="config-title">
<span class="host">pg-primary</span>:<span class="file">/etc/pgbackrest/pgbackrest.conf</span> <b>⇒</b> Configure <span class="br-option">repo1-retention-diff</span>
</div><div class="config-body"><div class="config-body-output">
[demo]<br/>
pg1-path=/var/lib/pgsql/10/data<br/>
<br/>
[global]<br/>
repo1-cipher-pass=zWaf6XtpjIVZC5444yXB+cgFDFl7MxGlgkZSaoPvTGirhPygu4jOKOXf9LO4vjfO<br/>
repo1-cipher-type=aes-256-cbc<br/>
repo1-path=/var/lib/pgbackrest<br/>
repo1-retention-diff=1<br/>
repo1-retention-full=2<br/>
start-fast=y<br/>
<br/>
[global:archive-push]<br/>
compress-level=3
</div></div></div><div class="section-body-text">
Backup <span class="br-setting">repo1-retention-diff=1</span> so two differentials will need to be performed before one is expired. An incremental backup is added to demonstrate incremental expiration. Incremental backups cannot be expired independently — they are always expired with their related full or differential backup.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Perform differential and incremental backups
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --type=diff backup</pre>
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --type=incr backup</pre>
</div></div><div class="section-body-text">
Now performing a differential backup will expire the previous differential and incremental backups leaving only one differential backup.
</div><div class="execute"><div class="execute-title">
<span class="host">pg-primary</span> <b>⇒</b> Perform a differential backup
</div><div class="execute-body">
<pre class="execute-body-cmd">sudo -u postgres pgbackrest --stanza=demo --type=diff \
--log-level-console=info backup</pre>
<pre class="execute-body-output"> [filtered 10 lines of output]
P00 INFO: backup command end: completed successfully
P00 INFO: expire command begin 2.38: --exec-id=1991-f827a85f --log-level-console=info --log-level-stderr=off --no-log-timestamp --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-diff=1 --repo1-retention-full=2 --stanza=demo</pre>
<pre class="execute-body-output-highlight">P00 INFO: repo1: expire diff backup set 20220306-154407F_20220306-154412D, 20220306-154407F_20220306-154414I</pre>
<pre class="execute-body-output">P00 INFO: repo1: remove expired backup 20220306-154407F_20220306-154414I
P00 INFO: repo1: remove expired backup 20220306-154407F_20220306-154412D
P00 INFO: expire command end: completed successfully</pre>
</div></div></div></div><div class="section2"><a id="retention/archive"></a><div class="section2-header"><div class="section2-number">
8.3
</div><div class="section2-title">