Backup from a Standby

pgBackRest can perform backups on a standby instead of the primary. Standby backups require the pg-standby host to be configured and the backup-standby option enabled. If more than one standby is configured then the first running standby found will be used for the backup.

Configure pg2-host/pg2-host-user and pg2-path

[demo]
pg2-path=/var/lib/postgresql/17/demo
[demo]
pg2-host-type=tls
[demo]
pg2-host=pg-standby
[demo]
pg2-host-ca-file=/etc/pgbackrest/cert/ca.crt
[demo]
pg2-host-cert-file=/etc/pgbackrest/cert/client.crt
[demo]
pg2-host-key-file=/etc/pgbackrest/cert/client.key
[global]
backup-standby=y

Both the primary and standby databases are required to perform the backup, though the vast majority of the files will be copied from the standby to reduce load on the primary. The database hosts can be configured in any order. pgBackRest will automatically determine which is the primary and which is the standby.

Backup the demo cluster from pg2

pgbackrest --stanza=demo --log-level-console=detail backup

This incremental backup shows that most of the files are copied from the pg-standby host and only a few are copied from the pg-primary host.

pgBackRest creates a standby backup that is identical to a backup performed on the primary. It does this by starting/stopping the backup on the pg-primary host, copying only files that are replicated from the pg-standby host, then copying the remaining few files from the pg-primary host. This means that logs and statistics from the primary database will be included in the backup.