ampgsql — Amanda Application to interface with PostgreSQL
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.
Tablespaces are not currently supported.
On versions of PostgreSQL earlier than 8.2, if the database is
quiet during a full backup, then the backup may not complete until
enough database activity takes place to trigger the archiving of the
current WAL file. Consider adjusting the PG-MAX-WAL-WAIT property from
its default (60s) to compensate. Note that you will need to increase
dtimeout
on the server accordingly.
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.
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.
Whether or not to remove old WAL segment files during base backups. Defaults to yes.
Database to connect to. Defaults to "template1" (which exists by default).
For restore command only, the data is recoved in that directory. Must be a unix path.
Which WAL files to archive when doing a full backup.
Backup all WAL files since the previous full backup.
Backup all WAL files since the previous backup (incr or full).
Backup all WAL files required for that full backup
The default is "INCR".
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 to connect to. If it starts with "/" it will be interepreted as a directory that holds the socket file. PostgreSQL defaults to /tmp.
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.
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.
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.
The TCP port to connect to, or the suffix of the socket file. PostgreSQL defaults to 5432.
Path to the psql binary. If not specified, the PATH environment variable will be searched.
Default: YES. Remove all WAL files included in the full backup.
Default: NO. If set to "YES" then remove all WAL files included in the incremental backup.
Directory for saving state about backups already made. The default is set when Amanda is built by the --with-gnutar-listdir configure option.
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 to connect as. It must be a superuser.
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).
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.
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.
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/
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