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https://github.com/postgrespro/pg_probackup.git
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Add documentation of pg_rman
Documentation is fairly refactored and rewritten, fixing many typos and many grammar mistakes in the previous version of the docs.
This commit is contained in:
Michael Paquier
parent
8efe5c9da4
commit
3f79be1789
2
Makefile
2
Makefile
@ -20,6 +20,8 @@ SRCS = \
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OBJS = $(SRCS:.c=.o)
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# pg_crc.c and are copied from PostgreSQL source tree.
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DOCS = pg_rman.txt
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# XXX for debug, add -g and disable optimization
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PG_CPPFLAGS = -I$(libpq_srcdir)
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PG_LIBS = $(libpq_pgport)
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444
pg_rman.txt
Normal file
444
pg_rman.txt
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@ -0,0 +1,444 @@
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pg_rman, Documentation
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======================
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pg_rman is a backup and recovery manager for PostgreSQL.
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It proposes the features below:
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- Backup while database runs including tablespaces with just one
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command
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- Recovery from backup with just one command, with customized targets
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to facilitate the use of PITR.
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- Support for full, incremental and archive backup
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- Compression of backup files
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- Management of backups with integrated catalog
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========
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Synopsis
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========
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pg_rman [ OPTIONS ]
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{ init |
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backup |
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restore |
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show [ DATE | timeline ] |
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validate [ DATE ] |
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delete DATE }
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DATE is the start time of the target backup in ISO-format:
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(YYYY-MM-DD HH:MI:SS). Prefix match is used to compare DATE and backup
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files.
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========
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Commands
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========
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pg_rman supports the following commands. See also Options for details of
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OPTIONS.
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init
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Initialize a backup catalog.
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backup
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Take an online backup.
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restore
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Perform restore.
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show
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Show backup history.
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The timeline option shows timeline of the backup and the parent's
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timeline for each backup.
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validate
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Validate backup files.
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delete
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Delete backup files.
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===========
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Description
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===========
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pg_rman is a utility program to backup and restore PostgreSQL database.
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It takes a physical online backup of whole database cluster, archive
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WALs, and server logs.
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- Initialize a backup catalog
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First, you need to create "a backup catalog" to store backup files and
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their metadata. It is recommended to setup archive_mode and archive_command
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in postgresql.conf before initializing the backup catalog. If the variables
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are initialized, pg_rman can adjust the config file to the setting. In this
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case, you have to specify the database cluster path for PostgreSQL. Please
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specify it in PGDATA environmental variable or -D/--pgdata option.
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$ pg_rman init -B <a backup catalog path>
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- Backup
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Backup target can be one of the following types. Also serverlogs can be added.
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Full backup
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Backup a whole database cluster.
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Incremental backup
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Backup only files or pages modified after the last verified backup.
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Archive WAL backup
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Backup only archive WAL files.
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It is recommended to verify backup files as soon as possible after backup.
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Unverified backup cannot be used in restore and in incremental backup.
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- Restore
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PostgreSQL server should be stopped before performing a restore. If database
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cluster still exists, restore command will save unarchived transaction log
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and delete all database files. You can retry recovery until a new backup is
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taken. After restoring files, pg_rman creates recovery.conf in $PGDATA. The
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conf file contains parameters for recovery. It is as well possible to modify
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the file manually.
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It is recommended to take a full backup as soon as possible after recovery
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has succeeded.
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If "--recovery-target-timeline" is not specifed, the last checkpoint's
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TimeLineID in control file ($PGDATA/global/pg_control) will be the restore
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target. If pg_control is not present, TimeLineID in the full backup used by
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the restore will be a restore target.
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========
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Examples
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========
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To reduce the number of command line arguments, you can set BACKUP_PATH,
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an environment variable, to the absolute path of the backup catalog and
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write default configuration into ${BACKUP_PATH}/pg_rman.ini.
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$ cat $BACKUP_PATH/pg_rman.ini
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ARCLOG_PATH = /home/postgres/arclog
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SRVLOG_PATH = /home/postgres/pgdata/pg_log
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BACKUP_MODE = F
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COMPRESS_DATA = YES
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KEEP_ARCLOG_FILES = 10
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KEEP_ARCLOG_DAYS = 10
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KEEP_DATA_GENERATIONS = 3
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KEEP_DATA_DAYS = 120
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KEEP_SRVLOG_FILES = 10
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KEEP_SRVLOG_DAYS = 10
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- Take a backup.
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This example takes a full backup of the whole database with server logs.
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Then, it validates all unvalidated backups.
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$ pg_rman backup --backup-mode=full --with-serverlog
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$ pg_rman validate
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- Restore from a backup.
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$ pg_ctl stop -m immediate
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$ pg_rman restore
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$ pg_ctl start
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- Show a backup
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$ pg_rman show
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===========================================================================================================
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Start Mode Current TLI Parent TLI Time Total Data WAL Log Backup Status
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===========================================================================================================
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2013-12-25 03:02:31 INCR 1 0 0m ---- 203kB 67MB ---- 67MB DONE
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2013-12-25 03:02:31 INCR 1 0 0m ---- 0B ---- ---- 0B ERROR
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2013-12-25 03:02:25 FULL 1 0 0m 33MB ---- 33MB ---- 64MB OK
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The fields are:
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- Start : start time of backup
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- Mode: Mode of backup
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-- FULL for a full backup
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-- INCR for an incremental backup
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-- ARCH for archive backup
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- Current TLI: current timeline of backup
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- Parent TLI: parent timeline of backup
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- Time : total time necessary to take this backup
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- Total : Total size of backup
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- Data : size of data files
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- WAL : size of read WAL archive files
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- Log : size of read server log files
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- Backup: size of backup (= written size)
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- Status: status of backup. Possible values are:
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-- OK : backup is done and validated.
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-- DONE : backup is done, but not validated yet.
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-- RUNNING : backup is running
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-- DELETING : backup is being deleted.
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-- DELETED : backup has been deleted.
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-- ERROR : backup is unavailable because some errors occur during backup.
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-- CORRUPT : backup is unavailable because it is broken.
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When a date is specified, more details about a backup is retrived:
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$ pg_rman show '2011-11-27 19:15:45'
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# configuration
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BACKUP_MODE=FULL
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WITH_SERVERLOG=false
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COMPRESS_DATA=false
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# result
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TIMELINEID=1
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START_LSN=0/08000020
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STOP_LSN=0/080000a0
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START_TIME='2011-11-27 19:15:45'
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END_TIME='2011-11-27 19:19:02'
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RECOVERY_XID=1759
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RECOVERY_TIME='2011-11-27 19:15:53'
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TOTAL_DATA_BYTES=1242420184
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READ_DATA_BYTES=25420184
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READ_ARCLOG_BYTES=32218912
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WRITE_BYTES=242919520
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BLOCK_SIZE=8192
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XLOG_BLOCK_SIZE=8192
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STATUS=OK
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You can check the "RECOVERY_XID" and "RECOVERY_TIME" which are used for
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restore option "--recovery-target-xid", "--recovery-target-time".
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The delete command deletes backup files not required by recovery after
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the specified date.
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=======
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Options
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=======
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pg_rman accepts the following command line parameters. Some of them can
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be also sepcified as environment variables. See also Parameters for the
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details.
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- Common options
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As a general rule, paths for data location need to be specified as
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absolute paths; relative paths are not allowed.
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-D PATH / --pgdata=PATH
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The absolute path of database cluster. Required on backup and
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restore.
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-A PATH / --arclog-path=PATH
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The absolute path of archive WAL directory. Required on backup
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and restore.
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-S PATH / --srvlog-path=PATH
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The absolute path of server log directory. Required on backup with
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server logs and restore.
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-B PATH / --backup-path=PATH
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The absolute path of backup catalog. This option is mandatory.
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-c / --check
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If specifed, pg_rman doesn't perform actual jobs but only checks
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parameters and required resources. The option is typically used with
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--verbose option to verify the operation.
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-v / --verbose
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If specified, pg_rman works in verbose mode.
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- Backup options
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-b { full | incremental | archive } /
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--backup-mode={ full | incremental | archive }
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Specify backup target files. Available options are: "full" backup,
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"incremental" backup, and "archive" backup. Abbreviated forms
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(prefix match) are also available. For example, -b f means "full"
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backup.
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full : Whole database backup and archive backup
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incremental : Incremental backup and archive backup
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archive : Only archive backup
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-s / --with-serverlog
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Backup server log files if specified.
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-Z / --compress-data
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Compress backup files with zlib if specified.
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-C / --smooth-checkpoint
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Checkpoint is performed on every backups. If the option is specified,
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do smooth checkpoint then. See also the second argument for
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pg_start_backup().
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--keep-data-generations / --keep-data-days
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Specify how long backuped data files will be kept.
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--keep-data-generations means number of backup generations.
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--keep-data-days means days to be kept.
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Only files exceeded both settings are deleted.
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--keep-arclog-files / --keep-arclog-days
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Specify how long backuped archive WAL files will be kept.
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--keep-arclog-files means number of backup files.
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--keep-arclog-days means days to be kept. When backup is run, only
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files exceeded both settings are deleted from archive storage.
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--keep-srvlog-files / --keep-srvlog-days
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Specify how long backuped serverlog files will be kept.
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--keep-srvlog-files means number of backup files.
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--keep-srvlog-days means days to be kept.
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When backup is run, only files exceeded both settings are deleted
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from server log directory (log_directory). This option works when
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you specify --with-serverlog and --srvlog-path options in backup
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command.
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- Restore options
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The parameters whose name start are started with --recovery refer to
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the same parameters as the ones in recovery.confin recovery.conf.
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--recovery-target-timeline TIMELINE
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Specifies recovering into a particular timeline.
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If not specified, the current timeline is used.
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--recovery-target-time TIMESTAMP
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This parameter specifies the timestamp up to which recovery will
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proceed.
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--recovery-target-xid XID
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This parameter specifies the transaction ID up to which recovery
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will proceed.
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--recovery-target-inclusive
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Specifies whether server pauses when recovery target is reached.
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--hard-copy
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Archived WAL files are copied to archive WAL storage area. If you
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do not specify --hard-copy, pg_rman makes symlink to archive WAL
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where are in the backup catalog directory.
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- Catalog options
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-a / --show-all
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Show all existing backups, including the deleted ones.
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- Connection options
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Parameters to connect PostgreSQL server.
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-d DBNAME / --dbname=DBNAME
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The database name to execute pg_start_backup() and pg_stop_backup().
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-h HOSTNAME / --host=HOSTNAME
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Specifies the host name of the machine on which the server is running.
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If the value begins with a slash, it is used as the directory for the
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Unix domain socket.
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-p PORT / --port=PORT
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Specifies the TCP port or local Unix domain socket file extension on
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which the server is listening for connections.
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-U USERNAME / --username=USERNAME
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User name to connect as.
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-w / --no-password
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Never issue a password prompt. If the server requires password
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authentication and a password is not available by other means such as
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a .pgpass file, the connection attempt will fail. This option can be
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useful in batch jobs and scripts where no user is present to enter a
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password.
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-W / --password
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Force pg_rman to prompt for a password before connecting to a database.
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This option is never essential, since pg_rman will automatically
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prompt for a password if the server demands password authentication.
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However, pg_rman will waste a connection attempt in order to find out
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if the server wants a password. In some cases it is worth typing -W
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to avoid the extra connection attempt.
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- Generic options
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--help
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Print help, then exit.
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-V / --version
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Print version information, then exit.
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-! / --debug
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Show debug information.
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==========
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Parameters
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==========
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Some of parameters can be specified as command line arguments, environment
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variables or in configuration file as follows:
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Short Long Environment Conf file
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-h --host PGHOST No
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-p --port PGPORT No
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-d --dbname PGDATABASE No
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-U --username PGUSER No
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PGPASSWORD No
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-w --password No
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-W --no-password No
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-D --pgdata PGDATA Yes
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-B --backup-path BACKUP_PATH Yes
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-A --arclog-path ARCLOG_PATH Yes
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-S --srvlog-path SRVLOG_PATH Yes
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-b --backup-mode BACKUP_MODE Yes
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-s --with-serverlog WITH_SERVERLOG Yes
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-Z --compress-data COMPRESS_DATA Yes
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-C --smooth-checkpoint SMOOTH_CHECKPOINT Yes
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--keep-data-generations KEEP_DATA_GENERATIONS Yes
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--keep-data-days KEEP_DATA_DAYS Yes
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--keep-srvlog-files KEEP_SRVLOG_FILES Yes
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--keep-srvlog-days KEEP_SRVLOG_DAYS Yes
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--keep-arclog-files KEEP_ARCLOG_FILES Yes
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--keep-arclog-days KEEP_ARCLOG_DAYS Yes
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--recovery-target-timeline RECOVERY_TARGET_TIMELINE Yes
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--recovery-target-xid RECOVERY_TARGET_XID Yes
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--recovery-target-time RECOVERY_TARGET_TIME Yes
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--recovery-target-inclusive RECOVERY_TARGET_INCLUSIVE Yes
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--hard-copy HARD_COPY Yes
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Variable names in configuration file are the same as long names or names
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of environment variables. The password can not be specified in command
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line and configuration file for security reason.
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This utility, like most other PostgreSQL utilities, also uses the
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environment variables supported by libpq (see Environment Variables)
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============
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Restrictions
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============
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pg_rman has the following restrictions.
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- Requires to read database cluster directory and write backup catalog
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directory. It is usually necessary to mount the disk where backup
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catalog is placed with NFS or related from database server.
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- Major versions of pg_rman and server should match.
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- Block sizes of pg_rman and server should match.
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- If there are some unreadable files/directories in data folder of server
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WAL directory or archived WAL directory, the backup or restore will fail
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depending on the backup mode selected.
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- Incremental backup is not able to take necessary files after a database
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creation, so take a full backup once a new database is created.
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=======
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Details
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=======
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- Recovery to Point-in-Time
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pg_rman can recover to point-in-time if timeline, transaction ID, or
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timestamp is specified in recovery.conf. xlogdump is a contrib module of
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PostgreSQL core that allows checking in the content of WAL files and
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determine when to recover. This might help.
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- Configuration file
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Setting parameters in configuration file is done as "name=value". Quotes
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are required if the value contains whitespaces. Comments should start with
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"#" and are automatically ignored. Whitespaces and tabs are ignored
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excluding values.
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- Exit codes
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pg_rman returns exit codes for each error status.
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Code Name Description
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0 SUCCESS Operation succeeded.
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1 HELP Print help, then exit
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2 ERROR Generic error
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3 FATAL Exit because of repeated errors
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4 PANIC Unknown critical condition
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10 ERROR_SYSTEM I/O or system error
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11 ERROR_NOMEM Out of memory
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12 ERROR_ARGS Invalid input parameters
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13 ERROR_INTERRUPTED Interrupted by user (Ctrl+C etc.)
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14 ERROR_PG_COMMAND SQL error
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15 ERROR_PG_CONNECT Cannot connect to PostgreSQL server
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20 ERROR_ARCHIVE_FAILED Cannot archive WAL files
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21 ERROR_NO_BACKUP Backup file not found
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22 ERROR_CORRUPTED Backup file is broken
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23 ERROR_ALREADY_RUNNING Cannot start because another pg_rman is running
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24 ERROR_PG_INCOMPATIBLE Version conflicted with server
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25 ERROR_PG_RUNNING Error due to server running
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26 ERROR_PID_BROKEN postmaster.pid is broken
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