Table of Contents
1
Introduction
Frequently Asked Questions are intended to provide details for specific questions that may or may not be covered in the User Guide, Configuration, or Command reference. If you are unable to find details for your specific issue here, remember that the pgBackRest Issues List in GitHub is also a valuable resource.
2
What if I get the could not find WAL segment error?
The cause of this error can be a result of many different issues, some of which may be:
  • misconfigured archive_command
  • misconfigured pgBackRest configuration files
  • network or permissions issue
  • third party product (e.g. S3, Swift or Minio) configuration issue
  • large amount of WAL queueing to be archived
It is advisable to:
  • check the archive_command in PostgreSQL
  • check the pgBackRest configuration settings on each host (e.g. pg* settings are set on the repository host and repo* settings on the pg host)
  • run the check command with --archive-timeout set to a higher value than in the pgBackRest configuration file (or default) to see if the WAL queue needs more time to clear. If the system is generating a lot of WAL, then consider configuring asyncronous archiving
3
How do I manually purge a backup set?
Backup sets in the middle cannot be expired, but it is possible to expire the oldest backup sets by running the expire command with retention. For example, the following command will keep only the last two full backups, purging any prior full backups including their associated incremental/differential backups and archive:
pgbackrest --stanza=xxx --repo1-retention-full=2 expire
Using the --repo1-retention-full option on the command- line simply overrides the setting in the configuration file for that one execution of the command. See the Retention section in the User Guide for more information on retention.
4
How can I configure options independently for each command?
pgBackRest has the ability to set options independently in the configuration file for each command. Configure Cluster Stanza details this feature as well as option precedence.
For example, the process-max option can be optimized for each command:
[global]
# used where not overridden
process-max=2

[global:backup]
# more cores for backup
process-max=4

[global:restore]
# all the cores for restore
process-max=8

[global:archive-push]
# more cores for archive-push
process-max=3

[global:archive-get]
# fewer cores for archive-get
process-max=1
5
Can I use dots (periods) in my S3 bucket name?
RFC-2818 does not allow wildcards to match on a dot (.) so s3 bucket names must not contain dots. If there are dots in the S3 bucket name then an error such as unable to find hostname 'my.backup.bucket.s3.amazonaws.com' in certificate common name or subject alternative names will occur.
6
Where can I find packages for older versions of pgBackRest?
The apt.postgresql.org repository maintains an archive of older versions. Debian also maintains snapshots of all test builds.