WALMGR(1)

NAME
walmgr - tools for managing WAL-based replication for PostgreSQL.

SYNOPSIS
walmgr.py <config.ini> command

DESCRIPTION
It is both admin and worker script for PostgreSQL PITR replication.

QUICK START

1.  Set up passwordless ssh authentication from master to slave
    master$ test -f ~/.ssh/id_dsa.pub || ssh-keygen -t dsa
    master$ cat ~/.ssh/id_dsa.pub | ssh slave cat \>\> .ssh/authorized_keys

2.  Configure paths
    master$ edit master.ini
    slave$ edit slave.ini
    Make sure that walmgr.py executable has same pathname on slave and master.

3.  Start archival process and create a base backup
    master$ ./walmgr.py master.ini setup
    master$ ./walmgr.py master.ini backup

4.  Prepare postgresql.conf and pg_hba.conf on slave and start replay
    master$ scp $PGDATA/*.conf slave:
    slave$ ./walmgr.py slave.ini restore
    For debian based distributions the standard configuration files are located
    in /etc/postgresql/x.x/main directory. If another scheme is used the postgresql.conf
    and pg_hba.conf should be copied to slave full_backup directory. Make sure to
    disable archive_command in slave config.
    in recovery mode.

5.  In-progress WAL segments can be backup by command:
    master$ ./walmgr.py master.ini sync

6.  If need to stop replay on slave and boot into normal mode, do:
    slave$ ./walmgr.py slave.ini boot

GENERAL OPTIONS
Common options to all walmgr.py commands.

-h, --help
    show this help message and exit

-q, --quiet
    make program silent

-v, --verbose
    make program more verbose

-n, --not-really
    Show what would be done without actually doing anything.

MASTER COMMANDS

  setup
Sets up postgres archiving, creates necessary directory structures on slave.

  sync
Synchronizes in-progress WAL files to slave.

  syncdaemon
Start WAL synchronization in daemon mode. This will start periodically synching the in-progress WAL files to slave. loop_delay use_xlog_functions

  stop
Deconfigures postgres archiving.

  periodic
Runs periodic command, if configured. This enables to execute arbitrary commands on interval, useful for synchronizing scripts, config files, crontabs etc.

  listbackups
List backup sets available on slave node.

  backup
Creates a new base backup from master database. Will purge expired backups and WAL files on slave if keep_backups is specified. During a backup a lock file is created in slave completed_wals directory. This is to prevent simultaneous backups and resulting corruption. If running backup is terminated, the BACKUPLOCK file may have to be removed manually.

  restore <set> <dst>
EXPERIMENTAL. Attempts to restore the backup from slave to master.

SLAVE COMMANDS

  boot
Stop log playback and bring the database up.

  pause
Pauses WAL playback.

  continue
Continues previously paused WAL playback.

  listbackups
Lists available backups.

  backup
EXPERIMENTAL. Creates a new backup from slave data. Log replay is paused, slave data directory is backed up to full_backup directory and log replay resumed. Backups are rotated as needed. The idea is to move the backup load away from production node. Usable from postgres 8.2 and up.

  restore [src][dst]
Restores the specified backup set to target directory. If specified without arguments the latest backup is moved to slave data directory (doesn't obey retention rules). If src backup is specified the backup is copied (instead of moving). Alternative destination directory can be specified with dst.

CONFIGURATION

  Common settings
Optional. Indentifies this script, used in logging. Keep unique if using central logging. Where to log. Optional. If nonzero, skylog.ini is used for log configuration.

  Master settings
Pid file location for syncdaemon mode (if running with -d). Otherwise not required. Database to connect to for pg_start_backup() etc. It is not a good idea to use dbname=template if running syncdaemon in record shipping mode. Master data directory location. Master postgresql.conf file location. This is where archive_command gets updated. Slave host and base directory. Slave directory where archived WAL files are copied. Slave directory where incomplete WAL files are stored. Slave directory where full backups are stored. The frequency of syncdaemon updates. In record shipping mode only incremental updates are sent, so smaller interval can be used. Use pg_xlog functions for record based shipping (available in 8.2 and up). If nonzero, a -z flag is added to rsync cmdline. Will reduce network traffic at the cost of extra CPU time. Shell script to be executed at specified time interval. Can be used for synchronizing scripts, config files etc. How ofter to run periodic command script. In seconds, and only evaluated at log switch times.

  Sample master.ini
[wal-master]
logfile              = master.log
pidfile              = master.pid
master_db            = dbname=template1
master_data          = /var/lib/postgresql/8.0/main
master_config        = /etc/postgresql/8.0/main/postgresql.conf
slave                = slave:/var/lib/postgresql/walshipping
completed_wals       = %(slave)s/logs.complete
partial_wals         = %(slave)s/logs.partial
full_backup          = %(slave)s/data.master
loop_delay           = 10.0
use_xlog_functions   = 1
compression          = 1

  Slave settings
Postgres data directory for the slave. This is where the restored backup is copied/moved. Script to stop postmaster on slave. Script to start postmaster on slave. Base directory for slave files (logs.comlete, data.master etc) Directory where complete WAL files are stored. Also miscellaneous control files are created in this directory (BACKUPLOCK, STOP, PAUSE, etc.). Directory where partial WAL files are stored. Directory where full backups are stored. Number of backups to keep. Also all WAL files needed to bring earliest backup up to date are kept. The backups are rotated before new backup is started, so at one point there is actually one less backup available. It probably doesn't make sense to specify keep_backups if periodic backups are not performed - the WAL files will pile up quickly. Backups will be named data.master, data.master.0, data.master.1 etc. Script to execute before rotating away the oldest backup. If it fails backups will not be rotated.

  Sample slave.ini
[wal-slave]
logfile              = slave.log
slave_data           = /var/lib/postgresql/8.0/main
slave_stop_cmd       = /etc/init.d/postgresql-8.0 stop
slave_start_cmd      = /etc/init.d/postgresql-8.0 start
slave                = /var/lib/postgresql/walshipping
completed_wals       = %(slave)s/logs.complete
partial_wals         = %(slave)s/logs.partial
full_backup          = %(slave)s/data.master
keep_backups         = 5