ampgsql - Man Page

Ampgsql is an Amanda Application API script. It should not be run by users directly. It implements on-line backups of PostgreSQL databases in conjunction with WAL archiving.

The diskdevice must be the cluster data directory, if it is "/var/lib/pgsql/data":

  HOST DISKNAME /var/lib/pgsql/data DUMPTYPE
or
  HOST /var/lib/pgsql/data DUMTYPE

This application implements the backup strategy described in http://www.postgresql.org/docs/current/static/continuous-archiving.html. For a level zero (full) backup, ampgsql:

• execute PG_START_BACKUP()
• dump the data directory
• execute PG_STOP_BACKUP()
• wait for the final WAL file to be archived
• back up the required WAL files
• optionally delete WAL files that are no longer necessary

The two dumps are made with GNU Tar, to data_dir.tar and archive_dir, respectively. They are then combined into a single tar file.

A level N backup creates a single tar file containing all WAL files since the previous level N-1 backup.

This section lists the amanda.conf(5) properties that control ampsql's functionality. See amanda-applications(7) for information on application properties and how they are configured.

ARCHIVEDIR

Directory that WAL segment files are archived to, as specified by the archive_command in PosgreSQL's postgresql.conf. The amanda user on the client must have at least read and execute permission on this directory, and preferably write. Without write permission, Amanda cannot clean up expired WAL and backup files.

CLEANUPWAL

Whether or not to remove old WAL segment files during base backups. Defaults to yes.

DB

Database to connect to. Defaults to "template1" (which exists by default).

DIRECTORY

For restore command only, the data is recoved in that directory. Must be a unix path.

FULL-WAL

Which WAL files to archive when doing a full backup.

FULL

Backup all WAL files since the previous full backup.

INCR

Backup all WAL files since the previous backup (incr or full).

NO

Backup all WAL files required for that full backup

The default is "INCR".

GNUTAR-PATH

Path to the GNU tar executable. This option only has an effect during restore. The default is set when Amanda is built by the --with-gnutar configure option.

HOST

Host to connect to. If it starts with "/" it will be interepreted as a directory that holds the socket file. PostgreSQL defaults to /tmp.

INCREMENTAL

Default: NO. If set to "YES", then backup only the WAL files since the previous backup.

It reduce the size of the backup, but amanda will not be able to restore all incrementals, the restore must be done manually.It is easier to set the dumptype bump* parameter to force a bump at every backup.

MAX-WAL-WAIT

The maximum amount of time to wait for PG_STOP_BACKUP to archive a WAL file. In versions of PostgreSQL before 8.2, PG_STOP_BACKUP does not automatically archive the latest WAL file, so a quiet database may wait a very long time before archiving the WAL file. Default: 60 seconds. Set to 0 to wait forever.

PASSFILE

Connect using the creditials in this file. Each line should have the format "hostname:port:database:username:password". The permissions must permit it to be read only by the user, or the file will not be used. Only usable with Postgres 8.1 and up.

PORT

The TCP port to connect to, or the suffix of the socket file. PostgreSQL defaults to 5432.

PSQL-PATH

Path to the psql binary. If not specified, the PATH environment variable will be searched.

REMOVE-FULL-WAL

Default: YES. Remove all WAL files included in the full backup.

REMOVE-INCREMENTAL-WAL

Default: NO. If set to "YES" then remove all WAL files included in the incremental backup.

STATEDIR

Directory for saving state about backups already made. The default is set when Amanda is built by the --with-gnutar-listdir configure option.

TMPDIR

Directory to use for temporary files during the backup process. It should have enough space to store a complete copy of the database. The default is set when Amanda is built by the --with-tmpdir configure option.

USER

User to connect as. It must be a superuser.

VERBOSE

Do not use the --quiet output of psql.

Client properties are deprecated. All properties should be set in the dumptype.

This section lists the amanda-client.conf(5) properties that control ampsql's functionality. If a property is prefixed with the diskname and an underscore, then it will be used when that diskname is being backed up. For example, if the properties PG-DATADIR and foo-PG-DATADIR are set, the value of PG-DATADIR will be used when bar and baz are being backed up, but foo-PG-DATADIR will be used when foo is being backed up. Disknames are specified in the disklist(5).

PG-ARCHIVEDIR

Directory that WAL segment files are archived to, as specified by the archive_command in PosgreSQL's postgresql.conf.  The amanda user on the client must have at least read and execute permission on this directory, and preferably write.  Without write permission, Amanda cannot clean up expired WAL and backup files.

PG-CLEANUPWAL

Whether or not to remove old WAL segment files during base backups. Defaults to yes.

PG-DATADIR

Cluster data directory

PG-DB

Database to connect to. Defaults to "template1" (which exists by default).

PG-HOST

Host to connect to. If it starts with "/" it will be interepreted as a directory that holds the socket file. PostgreSQL defaults to /tmp.

PG-MAX-WAL-WAIT

The maximum amount of time to wait for PG_STOP_BACKUP to archive a WAL file. In versions of PostgreSQL before 8.2, PG_STOP_BACKUP does not automatically archive the latest WAL file, so a quiet database may wait a very long time before archiving the WAL file. Default: 60 seconds. Set to 0 to wait forever.

PG-PASSFILE

Connect using the creditials in this file. Each line should have the format "hostname:port:database:username:password". The permissions must permit it to be read only by the user, or the file will not be used. Only usable with Postgres 8.1 and up.

PG-PASSWORD

Password to use when connecting. Deprecated in favor of passfiles.

PG-PORT

The TCP port to connect to, or the suffix of the socket file. PostgreSQL defaults to 5432.

PG-USER

User to connect as. It must be a superuser.

PSQL-PATH

Path to the psql binary. If not specified, the PATH environment variable will be searched.

Read the postgres documentation carefully before attempting a recovery. This section is only a rough guide to the process.

The data recovered from a postgres backup consists of a data tarball and one or more archive tarballs. The data contains the state of the database at the time the full backup was performed, and the archive tarballs contain postgres WAL files that must be re-run to generate a consistent state.

Ensure that the database server is shut down, and move the existing data directory aside. Untar the data tarball over this directory, and verify that ownership and permissions are correct. Untar all of the archive tarballs into a single directory - the archive directory. Create a recovery.conf in the data directory, owned by the proper user and with proper permissions. Add a restore_command to it, e.g.,

restore_command = 'cp /path/to/archive_dir/%f "%p"'

Start the database server, and examine the logs to track the process of the recovery. When the recovery is complete, the server will transition into a running state, and will move the recovery.conf file aside so that it will not attempt a recovery on the next invocation.

In amanda.conf:

define application app_ampgsql {
  plugin "ampgsql"
  property "HOST" "localhost"
  property "ARCHIVEDIR" "/tmp/archivedir"
  property "PASSFILE" "/etc/amanda/ampgsql.passwd"
}
define dumptype dump_ampgsql {
  global
  program "APPLICATION"
  application app_ampgsql
}

The disklist file:

  localhost /var/lib/pgsql/data dump_ampgsql
or
  localhost postgres /var/lib/pgsql/data dump_ampgsql

amanda(8), amanda.conf(5), amanda-client.conf(5), amanda-applications(7)

The Amanda Wiki: : http://wiki.zmanda.com/

Nikolas Coukouma <atrus@zmanda.com>

amanda(8), amanda-applications(7).