As repmgr uses pg_basebackup to clone a standby, it's possible to
provide additional parameters for pg_basebackup to customise the
cloning process.
By default, pg_basebackup performs a checkpoint before beginning the backup
process. However, a normal checkpoint may take some time to complete;
a fast checkpoint can be forced with repmgr standby clone's
-c/--fast-checkpoint option.
Note that this may impact performance of the server being cloned from (typically the primary)
so should be used with care.
If Barman is set up for the cluster, it's possible to clone the standby directly from Barman, without any impact on the server the standby is being cloned from. For more details see Cloning from Barman.
Other options can be passed to pg_basebackup by including them
in the repmgr.conf setting pg_basebackup_options.
Not that by default, repmgr executes pg_basebackup with -X/--wal-method
(PostgreSQL 9.6 and earlier: -X/--xlog-method) set to stream.
From PostgreSQL 9.6, if replication slots are in use, it will also create a replication slot before
running the base backup, and execute pg_basebackup with the
-S/--slot option set to the name of the previously created replication slot.
These parameters can set by the user in pg_basebackup_options, in which case they
will override the repmgr default values. However normally there's no reason to do this.
If using a separate directory to store WAL files, provide the option --waldir
(--xlogdir in PostgreSQL 9.6 and earlier) with the absolute path to the
WAL directory. Any WALs generated during the cloning process will be copied here, and
a symlink will automatically be created from the main data directory.
The --waldir (--xlogdir) option,
if present in pg_basebackup_options, will be honoured by repmgr
when cloning from Barman (repmgr 5.2 and later).
See the PostgreSQL pg_basebackup documentation for more details of available options.
If replication connections to a standby's upstream server are password-protected, the standby must be able to provide the password so it can begin streaming replication.
The recommended way to do this is to store the password in the postgres system
user's ~/.pgpass file. For more information on using the password file, see
the documentation section password file.
If using a pgpass file, an entry for the replication user (by default the
user who connects to the repmgr database) must
be provided, with database name set to replication, e.g.:
node1:5432:replication:repmgr:12345
If, for whatever reason, you wish to include the password in the replication configuration file,
set use_primary_conninfo_password to true in
repmgr.conf. This will read a password set in PGPASSWORD
(but not ~/.pgpass) and place it into the primary_conninfo
string in the replication configuration. Note that PGPASSWORD
will need to be set during any action which causes the replication configuration file to be
rewritten, e.g. repmgr standby follow.
In some circumstances it might be desirable to create a dedicated replication-only
user (in addition to the user who manages the repmgr metadata). In this case,
the replication user should be set in repmgr.conf via the parameter
replication_user; repmgr will use this value when making
replication connections and generating the replication configuration. This
value will also be stored in the parameter repmgr.nodes
table for each node; it no longer needs to be explicitly specified when
cloning a node or executing repmgr standby follow.
repmgr provides a tablespace_mapping configuration
file option, which will makes it possible to map the tablespace on the source node to
a different location on the local node.
To use this, add tablespace_mapping to repmgr.conf
like this:
tablespace_mapping='/var/lib/pgsql/tblspc1=/data/pgsql/tblspc1'
where the left-hand value represents the tablespace on the source node, and the right-hand value represents the tablespace on the standby to be cloned.
This parameter can be provided multiple times.