Restore an AlloyDB Omni cluster using pgBackRest

This page shows you how to restore an AlloyDB Omni cluster using a backup created with pgBackRest, the open-source backup solution included with the AlloyDB Omni Docker container.

Because AlloyDB Omni is compatible with PostgreSQL, the data-restoration commands and techniques described by the pgBackRest manual apply to AlloyDB Omni as well. This page demonstrates a selection of common recovery tasks, with examples of relevant commands.

For more information about configuring pgBackRest to work with AlloyDB Omni, see Set up pgBackRest for AlloyDB Omni.

Before you begin

Before configuring AlloyDB Omni to work with pgBackrest, you need to have AlloyDB Omni installed and running on a server that you control.

A target database server, running the same major version of AlloyDB Omni as the source database server. For more information about installing AlloyDB Omni, see Install AlloyDB Omni.

The target server can be the same machine as the source server.
A pgBackRest backup repository containing at least one backup of the source AlloyDB Omni database.
Enough free disk space on the target server to hold the restored database.

Overview

To perform a AlloyDB Omni restore using pgBackRest, run the pgbackrest restore command. The arguments that you provide the command vary depending upon your situation.

In general, you run the pgbackrest restore command with flags that provide the following information:

The location of your pgbackrest.conf file.
The name of pgBackRest backup repository that you want to restore from. These repositories are named and defined in the pgbackest.conf file.
The location on the local file system to write the restored data to.
An identifier of the particular backup or point in time that you want to restore from.

When running the containerized pgbackrest restore commands, remember to use file system paths from the container's point of view. For example, the path to your AlloyDB Omni data directory is always /mnt/disks/pgsql, no matter its location on your host server. For more information, see A note about file system paths.

Perform a point-in-time restore

This example restores data from a pgBackRest repository, naming a particular point in time to restore from. If you have defined multiple repositories in the target environment's the pgbackrest.conf file, then pgBackRest chooses the repository to restore from based on availability, expected speed, and other factors.

The example assumes the following:

You have a pgbackrest.conf file located at the top level of your target AlloyDB Omni data directory. This makes the file available to the containerized pgbackrest as /mnt/disks/pgsql/pgbackrest.conf.
You have enabled continuous backups with your pgBackRest configuration.

In the target environment, perform a PITR restore, specifying a timestamp to restore from:
```
sudo docker exec pg-service pgbackrest \
  --config-path=/mnt/disks/pgsql \
  --stanza=STANZA \
  --type=time \
  --pg1-path=/mnt/disks/pgsql/data-RESTORED \
  --target="TIMESTAMP" \
  restore
```
Replace the following:
- STANZA: the configuration stanza, defined by the pgbackrest.conf file, to apply to this restore—for example, omni.
- TIMESTAMP: the time to restore from—for example, 2024-02-22 19:50:00.
On the target environment, stop the database server:
```
sudo alloydb database-server stop
```
Rename the data subdirectory of your data directory, as a safety precaution:
```
cd DATA_DIR
sudo mv data data-OLD
```
Replace DATA_DIR with the file system path to your AlloyDB Omni data directory.

Move the restored data into place, and clean up postgresql.auto.conf:

sudo mv data-RESTORED data
sudo sed -i 's|data-RESTORED|data|' data/postgresql.auto.conf

Start the database server:
```
sudo alloydb database-server start
```

You can now connect to your database using psql and confirm that the data has been restored as you expect. If so, you can delete the data-OLD copy of the data subdirectory that you created earlier.

For more information about PITR in pgBackRest, see Point-in-Time Recovery. For more information about preparing a pgbackrest.conf file for use with AlloyDB Omni, see Set up pgBackRest for AlloyDB Omni.

Other options

The pgbackrest restore command is very flexible, with an array of options and features that you can control through passing in different command-line options. These include the following:

Limiting a restore only to changed files.
Restoring only selected databases.

For a complete guide to performing restores in pgBackRest, see Restore.