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2 Overview : 2.1 Block-Level Incremental Backup : 2.1.1 Incremental Backup Limitations and Requirements

Create or select an operating system account to be used as the BART user account. See Establishing the BART User Account Section of EDB Postgres Backup and Recovery Installation and Upgrade Guide for information about choosing and setting up the BART user account.
In the BART configuration file, the cluster_owner parameter must be set to the Linux operating system user account that owns the directory of the database cluster from which incremental backups are to be taken. The allow_incremental_backups parameter must be enabled. See Configuring the Database Server Section of EDB Postgres Backup and Recovery Installation and Upgrade Guide for information.
Note: This password-less SSH/SCP connection must be established even if BART and the database server are running on the same host and the BART user account and the cluster_owner user account are the same account. See Authorizing SSH/SCP Access without a Password Section of EDB Postgres Backup and Recovery Installation and Upgrade Guide for information.
In addition to the BART host where the BART backup catalog resides, the BART package must also be installed on every remote database server on which incremental backups are to be restored. In order to restore an incremental backup, the bart program must be executable on the remote host by the remote user specified by the remote_host parameter in the BART configuration file or by the -r option when using the RESTORE subcommand to restore the incremental backup. See Section 2.1.5.2 for information about restoring incremental backups on remote hosts.
For restoring incremental backups on a remote database server, a password-less SSH/SCP connection must be established from the BART user account on the BART host to the remote user on the remote host that is specified by the remote_host parameter in the BART configuration file or by the -r option when using the RESTORE subcommand to restore the incremental backup. See Section 2.1.5.2 for information about restoring incremental backups on remote hosts.
Compression of archived WAL files in the BART backup catalog is not permitted for database servers on which incremental backups are to be taken. The wal_compression setting in the BART configuration file must not be enabled for those database servers. Disabled is the default setting unless the parameter is altered in the global section or the server section. See Configuring the BART host and Configuring the Database Server Sections of EDB Postgres Backup and Recovery Installation and Upgrade Guide for information about the wal_compression parameter.

3.
An initial full backup must be taken with the BACKUP subcommand. This full backup establishes the parent of the first incremental backup.
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Incremental backups are taken using the BACKUP subcommand with the --parent option to specify the backup identifier or name of a previous, full backup or an incremental backup. Any previous backup may be chosen as the parent as long as all backups belong to the same timeline.
Note: Multiple block copier threads can be used to copy the modified blocks to the incremental backup directory. See Configuring the BART host and Configuring the Database Server Sections of EDB Postgres Backup and Recovery Installation and Upgrade Guide for setting the thread_count parameter in the BART configuration file. See Section 3.4.3 for using the --thread-count option with the BACKUP subcommand.
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The restore process for an incremental backup is invoked using the RESTORE subcommand in the same manner as restoring a full backup. The -i option specifies the backup identifier or name of the incremental backup to restore. The restore process begins by going back through the chain of past, parent incremental backups until the initial full backup starting the chain is identified. This full backup provides the initial set of directories and files to be restored to the location specified with the -p option.
The WAL scanner determines which blocks have been modified and records the information in a file called the modified block map (MBM) file. One MBM file is created for each WAL file.
backup_path/server_name/archived_wals
backup_path is the BART backup catalog parent directory specified in the global section of the BART configuration file.
server_name is the lowercase conversion of the database server name specified for this database server in the server section of the BART configuration file.
Note: Under certain circumstances such as when the rsync utility is used to copy WAL files to the BART backup catalog, the WAL files may have been missed by the WAL scanner program for scanning and creation of MBM files. Use the scan_interval parameter in the BART configuration file to force scanning of WAL files in the archive directory of the BART backup catalog to ensure MBM files are generated. See Configuring the BART host and Configuring the Database Server Sections of EDB Postgres Backup and Recovery Installation and Upgrade Guide for more information.
See Section 3.5 for information about using the WAL scanner.

2 Overview : 2.1 Block-Level Incremental Backup : 2.1.1 Incremental Backup Limitations and Requirements

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