walmgr3 - tool for managing WAL-based replication for PostgreSQL.
walmgr3 <config.ini> command [--not-really] [options]
Walmgr3 is a tool to handle replication of PostgreSQL with PITR (also known as Log Shipping).
This script allows to setup and administer the replication, it is also used by PostgreSQL to archive and restore the WAL files.
See QUICK START below to start your first log shipping in few steps.
The command is one of the Master, Slave, Common or Internal commands listed below.
Print version info and exit.
Show this help message and exit.
Log only errors and warnings.
Run in daemon mode (go background).
Show what would be done without actually doing anything.
Display sample ini file.
Override config setting
Initialize Master walmgr3 configuration.
Initialize Slave walmgr3 configuration.
Configuration file location for --init-X commands.
Slave host name.
PostgreSQL data directory.
Generate a SSH key pair if needed (used in Master).
Add the public key file to authorized_hosts file (used in Slave).
Remove Master ssh key from authorized_hosts file (used in Slave).
Provide the connection string to the streaming replication Master (used in Slave).
Add password for streaming replication from plain text file to .pgpass. Additional fields for password file entry will be extracted from primary-conninfo (used in Slave).
Remove .pgpass entry, which was used for streaming replication (used in Slave)
Do the same thing as command synch-standby, but walmgr ini file is not used. This option can be used when walmgr ini is not available. It tries to guess the postgres config location, --pgdata option may also be needed. (used in Master)
Reload config (send SIGHUP).
Stop program safely (send SIGINT).
Kill program immediately (send SIGTERM).
Sets up PostgreSQL for WAL archiving, creates necessary directory structures on Slave.
Copies in-progress WAL files to Slave.
Start WAL synchronization in daemon mode. This will start periodically synching the in-progress WAL files to Slave.
The following configuration parameters are used to drive the syncdaemon:
|o||loop_delay - how long to sleep between the synchs.|
|o||use_xlog_functions - use record based shipping to synchronize in-progress WAL segments.|
Stop archiving and de-configure PostgreSQL archiving.
Runs periodic command if configured. This enables to execute arbitrary commands on interval, useful for synchronizing scripts, config files, crontabs etc.
Enables/disables synchronous streaming replication for given application name(s). Does additional check before enabling synchronous mode.
Stop WAL playback and bring the database up so it can accept queries.
Pauses WAL playback.
Continues previously paused WAL playback.
Creates backup from Master database using streaming replication. Also creates recovery.conf and starts slave standby. Backup is created with pg_basebackup and pg_receivexlog (available in 9.2 and up).
Lists available backups on Slave node.
Creates a new base backup from Master database. Will purge expired backups and WAL files on Slave if keep_backups is not 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.
EXPERIMENTAL: If run on Slave, creates backup from in-recovery Slave data. WAL playback is paused, Slave data directory is backed up to full_backup directory and WAL playback is resumed. Backups are rotated as needed. The idea is to move the backup load away from production node. Usable from PostgreSQL 8.2 and up.
Restores the specified backup set to target directory. If specified without arguments the latest backup is moved to Slave data directory (doesn\(cqt obey retention rules). If src backup is specified the backup is copied (instead of moved). Alternative destination directory can be specified with dst.
Cleanup any walmgr3 files after stop.
xarchive <srcpath> <srcname>
On Master, archive one WAL file.
xrestore <srcname> <dstpath> [last restartpoint wal]
On Slave, restore one WAL file.
On Master, create lock file to deny other concurrent backups.
On Slave, remove backup lock file, allow other backup to run.
Rotate backups by increasing backup directory suffixes. Note that since we also have to make room for next backup, we actually have keep_backups - 1 backups available after this.
Unneeded WAL files are not removed here, it is handled by xpurgewals command instead.
On Slave, remove WAL files not needed for recovery.
xpartialsync <filename> <offset> <bytes>
Read bytes worth of data from stdin, append to the partial WAl file starting from offset. On error it is assumed that master restarts from zero.
The resulting file is always padded to XLOG_SEGMENT_SIZE bytes to simplify recovery.
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.
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.
The command to restart Master database, this used after changing archive_mode parameter. Leave unset if you cannot afford to restart the database at setup/stop.
Slave host and base directory.
Configuration file location for the Slave walmgr3.
Slave directory where archived WAL files are copied.
Slave directory where incomplete WAL files are stored.
Slave directory where full backups are stored.
Optional. Slave directory where configuration file 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. It reduces network traffic at the cost of extra CPU time.
Keep symlinks for pg_xlog and pg_log.
If set to 1, walmgr3 setup will set wal_level to hot_standby (PostgreSQL 9.0 and newer).
How ofter to run periodic command script. In seconds, and only evaluated at log switch times.
Shell script to be executed at specified time interval. Can be used for synchronizing scripts, config files etc.
[walmgr] job_name = wal-master logfile = ~/log/%(job_name)s.log pidfile = ~/pid/%(job_name)s.pid use_skylog = 1
master_db = dbname=my_db master_data = /var/lib/postgresql/9.1/main master_config = /etc/postgresql/9.1/main/postgresql.conf master_bin = /usr/lib/postgresql/9.1/bin
# set this only if you can afford database restarts during setup and stop. #master_restart_cmd = /etc/init.d/postgresql-9.1 restart
slave = slave-host slave_config = /var/lib/postgresql/conf/wal-slave.ini
walmgr_data = /var/lib/postgresql/walshipping completed_wals = %(walmgr_data)s/logs.complete partial_wals = %(walmgr_data)s/logs.partial full_backup = %(walmgr_data)s/data.master config_backup = %(walmgr_data)s/config.backup
# syncdaemon update frequency loop_delay = 10.0 # use record based shipping available since 8.2 use_xlog_functions = 0
# pass -z to rsync, useful on low bandwidth links compression = 0
# keep symlinks for pg_xlog and pg_log keep_symlinks = 1
# tell walmgr to set wal_level to hot_standby during setup #hot_standby = 1
# periodic sync #command_interval = 600 #periodic_command = /var/lib/postgresql/walshipping/periodic.sh
PostgreSQL data directory for the Slave. This is where the restored backup is copied/moved.
Specifies the location of PostgreSQL binaries (pg_controldata, etc). Needed if they are not already in the PATH.
Script to stop PostgreSQL on Slave.
Script to start PostgreSQL on Slave.
Directory for PostgreSQL configuration files. If specified, walmgr3 restore attempts to restore configuration files from config_backup directory.
Set to the directory on the Slave where pg_xlog files get written to. On a restore to the Slave walmgr3 will create a symbolic link from data/pg_xlog to this location.
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.
Optional. Slave directory where configuration file backups are stored.
Set backup_datadir to no to prevent walmgr3 from making a backup of the data directory when restoring to the Slave. This defaults to yes.
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\(cqt 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.
Primary database connection string for hot standby - enabling this will cause the Slave to be started in hot standby mode.
[walmgr] job_name = wal-slave logfile = ~/log/%(job_name)s.log use_skylog = 1
slave_data = /var/lib/postgresql/9.1/main slave_bin = /usr/lib/postgresql/9.1/bin slave_stop_cmd = /etc/init.d/postgresql-9.1 stop slave_start_cmd = /etc/init.d/postgresql-9.1 start slave_config_dir = /etc/postgresql/9.1/main
# alternative pg_xlog directory for slave, symlinked to pg_xlog on restore #slave_pg_xlog = /vol2/pg_xlog
walmgr_data = ~/walshipping completed_wals = %(walmgr_data)s/logs.complete partial_wals = %(walmgr_data)s/logs.partial full_backup = %(walmgr_data)s/data.master config_backup = %(walmgr_data)s/config.backup
backup_datadir = yes keep_backups = 0 archive_command =
# primary database connect string for hot standby -- enabling # this will cause the slave to be started in hot standby mode. #primary_conninfo = host=master port=5432 user=postgres
Successful program execution.
PostgreSQL environment variables can be used.
|1.||Set up passwordless ssh-key on Master and write configuration file|
master$ walmgr3 --ssh-keygen --init-master --slave <slave_hostname>
|2.||Set up passwordless ssh authentication from Master to Slave and write configuration file on Slave|
slave$ walmgr3 --init-slave --ssh-add-key=/tmp/id_rsa.pub
|3.||Logging setup on Master and Slave|
master$ cp skylog.ini ~postgres/ slave$ cp skylog.ini ~postgres/
|4.||Start archival process and create a base backup|
master$ walmgr3 /var/lib/postgresql/conf/wal-master.ini setup master$ walmgr3 /var/lib/postgresql/conf/wal-master.ini backup
CAUTION: starting from PostgreSQL 8.3 the archiving is enabled by setting archive_mode GUC to on. However changing this parameter requires the server to be restarted.
|5.||Prepare postgresql.conf and pg_hba.conf on Slave and start replay|
slave$ walmgr3 /var/lib/postgresql/conf/wal-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.
walmgr3 restore moves data in place, creates recovery.conf and starts postmaster in recovery mode.
|6.||In-progress WAL segments can be backup by command:|
master$ walmgr3 /var/lib/postgresql/conf/wal-master.ini sync
|7.||If need to stop replay on Slave and boot into normal mode, do:|
slave$ walmgr3 /var/lib/postgresql/conf/wal-slave.ini boot