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Add functionality to "pause" repmgrd

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In some circumstances, e.g. while performing a switchover, it is essential
that repmgrd does not take any kind of failover action, as this will put
the cluster into an incorrect state.

Previously it was necessary to stop repmgrd on all nodes (or at least
those nodes which repmgrd would consider as promotion candidates), however
this is a cumbersome and potentially risk-prone operation, particularly if the
replication cluster contains more than a couple of servers.

To prevent this issue from occurring, this patch introduces the ability
to "pause" repmgrd on all nodes wth a single command ("repmgr daemon pause")
which notifies repmgrd not to take any failover action until the node
is "unpaused" ("repmgr daemon unpause").

"repmgr daemon status" provides an overview of each node and whether repmgrd
is running, and if so whether it is paused.

"repmgr standby switchover" has been modified to automatically pause repmgrd
while carrying out the switchover.

See documentation for further details.
This commit is contained in:
Ian Barwick
2018-09-27 16:42:10 +09:00
parent fce3c02760
commit 2491b8ae52
27 changed files with 1943 additions and 121 deletions
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4
doc/filelist.sgml
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@@ -58,6 +58,7 @@
<!ENTITY repmgrd-cascading-replication SYSTEM "repmgrd-cascading-replication.sgml">
<!ENTITY repmgrd-network-split SYSTEM "repmgrd-network-split.sgml">
<!ENTITY repmgrd-witness-server SYSTEM "repmgrd-witness-server.sgml">
<!ENTITY repmgrd-pausing SYSTEM "repmgrd-pausing.sgml">
<!ENTITY repmgrd-bdr SYSTEM "repmgrd-bdr.sgml">
<!ENTITY repmgr-primary-register SYSTEM "repmgr-primary-register.sgml">
@@ -78,6 +79,9 @@
<!ENTITY repmgr-cluster-crosscheck SYSTEM "repmgr-cluster-crosscheck.sgml">
<!ENTITY repmgr-cluster-event SYSTEM "repmgr-cluster-event.sgml">
<!ENTITY repmgr-cluster-cleanup SYSTEM "repmgr-cluster-cleanup.sgml">
<!ENTITY repmgr-daemon-status SYSTEM "repmgr-daemon-status.sgml">
<!ENTITY repmgr-daemon-pause SYSTEM "repmgr-daemon-pause.sgml">
<!ENTITY repmgr-daemon-unpause SYSTEM "repmgr-daemon-unpause.sgml">
<!ENTITY appendix-release-notes SYSTEM "appendix-release-notes.sgml">
<!ENTITY appendix-faq SYSTEM "appendix-faq.sgml">

4
doc/repmgr-cluster-show.sgml
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@@ -90,7 +90,7 @@
<para>
<command>repmgr cluster show</command> accepts an optional parameter <literal>--csv</literal>, which
outputs the replication cluster's status in a simple CSV format, suitable for
parsing by scripts:
parsing by scripts, e.g.:
<programlisting>
$ repmgr -f /etc/repmgr.conf cluster show --csv
1,-1,-1
@@ -165,7 +165,7 @@
<refsect1>
<title>See also</title>
<para>
<xref linkend="repmgr-node-status">, <xref linkend="repmgr-node-check">
<xref linkend="repmgr-node-status">, <xref linkend="repmgr-node-check">, <xref linkend="repmgr-daemon-status">
</para>
</refsect1>

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doc/repmgr-daemon-pause.sgml Normal file
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@@ -0,0 +1,109 @@
<refentry id="repmgr-daemon-pause">
<indexterm>
<primary>repmgr daemon pause</primary>
</indexterm>
<refmeta>
<refentrytitle>repmgr daemon pause</refentrytitle>
</refmeta>
<refnamediv>
<refname>repmgr daemon pause</refname>
<refpurpose>Instruct all <application>repmgrd</application> instances in the replication cluster to pause failover operations</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
This command can be run on any active node in the replication cluster to instruct all
running <application>repmgrd</application> instances to &quot;pause&quot; themselves, i.e. take no
action (such as promoting themselves or following a new primary) if a failover event is detected.
</para>
<para>
This functionality is useful for performing maintenance operations, such as switchovers
or upgrades, which might otherwise trigger a failover if <application>repmgrd</application>
is running normally.
</para>
<note>
<para>
It's important to wait a few seconds after restarting PostgreSQL on any node before running
<command>repmgr daemon pause</command>, as the <application>repmgrd</application> instance
on the restarted node will take a second or two before it has updated its status.
</para>
</note>
<para>
<xref linkend="repmgr-daemon-unpause"> will instruct all previously paused <application>repmgrd</application>
instances to resume normal failover operation.
</para>
</refsect1>
<refsect1>
<title>Execution</title>
<para>
<command>repmgr daemon pause</command> can be executed on any active node in the
replication cluster. A valid <filename>repmgr.conf</filename> file is required.
It will have no effect on previously paused nodes.
</para>
</refsect1>
<refsect1>
<title>Example</title>
<para>
<programlisting>
$ repmgr -f /etc/repmgr.conf daemon pause
NOTICE: node 1 (node1) paused
NOTICE: node 2 (node2) paused
NOTICE: node 3 (node3) paused</programlisting>
</para>
</refsect1>
<refsect1>
<title>Options</title>
<variablelist>
<varlistentry>
<term><option>--dry-run</option></term>
<listitem>
<para>
Check if nodes are reachable but don't pause <application>repmgrd</application>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit codes</title>
<para>
Following exit codes can be emitted by <command>repmgr daemon unpause</command>:
</para>
<variablelist>
<varlistentry>
<term><option>SUCCESS (0)</option></term>
<listitem>
<para>
<application>repmgrd</application> could be paused on all nodes.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_REPMGRD_PAUSE (26)</option></term>
<listitem>
<para>
<application>repmgrd</application> could not be paused on one or mode nodes.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See also</title>
<para>
<xref linkend="repmgr-daemon-unpause">, <xref linkend="repmgr-daemon-status">
</para>
</refsect1>
</refentry>

165
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@@ -0,0 +1,165 @@
<refentry id="repmgr-daemon-status">
<indexterm>
<primary>repmgr daemon status</primary>
</indexterm>
<refmeta>
<refentrytitle>repmgr daemon status</refentrytitle>
</refmeta>
<refnamediv>
<refname>repmgr daemon status</refname>
<refpurpose>display information about the status of <application>repmgrd</application> on each node in the cluster</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
This command provides an overview over all active nodes in the cluster and the state
of each node's <application>repmgrd</application> instance. It can be used to check
the result of <xref linkend="repmgr-daemon-pause"> and <xref linkend="repmgr-daemon-unpause">
operations.
</para>
</refsect1>
<refsect1>
<title>Execution</title>
<para>
<command>repmgr daemon status</command> can be executed on any active node in the
replication cluster. A valid <filename>repmgr.conf</filename> file is required.
</para>
<note>
<para>
After restarting PostgreSQL on any node, the <application>repmgrd</application> instance
will take a second or two before it is able to update its status. Until then,
<application>repmgrd</application> will be shown as not running.
</para>
</note>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
<application>repmgrd</application> running normally on all nodes:
<programlisting>$ repmgr -f /etc/repmgr.conf daemon status
ID | Name | Role | Status | repmgrd | PID | Paused?
----+-------+---------+---------+---------+------+---------
1 | node1 | primary | running | running | 7851 | no
2 | node2 | standby | running | running | 7889 | no
3 | node3 | standby | running | running | 7918 | no</programlisting>
</para>
<para>
<application>repmgrd</application> paused on all nodes (using <xref linkend="repmgr-daemon-pause">):
<programlisting>$ repmgr -f /etc/repmgr.conf daemon status
ID | Name | Role | Status | repmgrd | PID | Paused?
----+-------+---------+---------+---------+------+---------
1 | node1 | primary | running | running | 7851 | yes
2 | node2 | standby | running | running | 7889 | yes
3 | node3 | standby | running | running | 7918 | yes</programlisting>
</para>
<para>
<application>repmgrd</application> not running on one node:
<programlisting>$ repmgr -f /etc/repmgr.conf daemon status
ID | Name | Role | Status | repmgrd | PID | Paused?
----+-------+---------+---------+-------------+------+---------
1 | node1 | primary | running | running | 7851 | yes
2 | node2 | standby | running | not running | n/a | n/a
3 | node3 | standby | running | running | 7918 | yes</programlisting>
</para>
</refsect1>
<refsect1>
<title>Options</title>
<variablelist>
<varlistentry>
<term><option>--csv</option></term>
<listitem>
<para>
<command>repmgr daemon status</command> accepts an optional parameter <literal>--csv</literal>, which
outputs the replication cluster's status in a simple CSV format, suitable for
parsing by scripts, e.g.:
<programlisting>
$ repmgr -f /etc/repmgr.conf daemon status --csv
1,node1,primary,1,1,10204,1
2,node2,standby,1,0,-1,1
3,node3,standby,1,1,10225,1</programlisting>
</para>
<para>
The columns have following meanings:
<itemizedlist spacing="compact" mark="bullet">
<listitem>
<simpara>
node ID
</simpara>
</listitem>
<listitem>
<simpara>
node name
</simpara>
</listitem>
<listitem>
<simpara>
node type (primary or standby)
</simpara>
</listitem>
<listitem>
<simpara>
PostgreSQL server running
</simpara>
</listitem>
<listitem>
<simpara>
<application>repmgrd</application> running (1 = running, 0 = not running)
</simpara>
</listitem>
<listitem>
<simpara>
<application>repmgrd</application> PID (-1 if not running)
</simpara>
</listitem>
<listitem>
<simpara>
<application>repmgrd</application> paused (1 = paused, 0 = not paused)
</simpara>
</listitem>
</itemizedlist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--verbose</option></term>
<listitem>
<para>
Display the full text of any database connection error messages
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See also</title>
<para>
<xref linkend="repmgr-daemon-pause">, <xref linkend="repmgr-daemon-unpause">, <xref linkend="repmgr-cluster-show">
</para>
</refsect1>
</refentry>

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@@ -0,0 +1,103 @@
<refentry id="repmgr-daemon-unpause">
<indexterm>
<primary>repmgr daemon unpause</primary>
</indexterm>
<refmeta>
<refentrytitle>repmgr daemon unpause</refentrytitle>
</refmeta>
<refnamediv>
<refname>repmgr daemon unpause</refname>
<refpurpose>Instruct all <application>repmgrd</application> instances in the replication cluster to resume failover operations</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
This command can be run on any active node in the replication cluster to instruct all
running <application>repmgrd</application> instances to &quot;unpause&quot;
(following a previous execution of <xref linkend="repmgr-daemon-pause">)
and resume normal failover/monitoring operation.
</para>
<note>
<para>
It's important to wait a few seconds after restarting PostgreSQL on any node before running
<command>repmgr daemon pause</command>, as the <application>repmgrd</application> instance
on the restarted node will take a second or two before it has updated its status.
</para>
</note>
</refsect1>
<refsect1>
<title>Execution</title>
<para>
<command>repmgr daemon unpause</command> can be executed on any active node in the
replication cluster. A valid <filename>repmgr.conf</filename> file is required.
It will have no effect on nodes which are not already paused.
</para>
</refsect1>
<refsect1>
<title>Example</title>
<para>
<programlisting>
$ repmgr -f /etc/repmgr.conf daemon unpause
NOTICE: node 1 (node1) unpaused
NOTICE: node 2 (node2) unpaused
NOTICE: node 3 (node3) unpaused</programlisting>
</para>
</refsect1>
<refsect1>
<title>Options</title>
<variablelist>
<varlistentry>
<term><option>--dry-run</option></term>
<listitem>
<para>
Check if nodes are reachable but don't unpause <application>repmgrd</application>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit codes</title>
<para>
Following exit codes can be emitted by <command>repmgr daemon unpause</command>:
</para>
<variablelist>
<varlistentry>
<term><option>SUCCESS (0)</option></term>
<listitem>
<para>
<application>repmgrd</application> could be unpaused on all nodes.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_REPMGRD_PAUSE (26)</option></term>
<listitem>
<para>
<application>repmgrd</application> could not be unpaused on one or mode nodes.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See also</title>
<para>
<xref linkend="repmgr-daemon-pause">, <xref linkend="repmgr-daemon-status">
</para>
</refsect1>
</refentry>

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@@ -35,6 +35,10 @@
&repmgr; will attempt to check for potential issues but cannot guarantee
a successful switchover.
</para>
<para>
&repmgr; will refuse to perform the switchover if an exclusive backup is running on
the current primary.
</para>
</note>
<para>
For more details on performing a switchover, including preparation and configuration,
@@ -43,11 +47,14 @@
<note>
<para>
<application>repmgrd</application> should not be active on any nodes while a switchover is being
executed. This restriction may be lifted in a later version.
From <link linkend="release-4.2">repmgr 4.2</link>, &repmgr; will instruct any running
<application>repmgrd</application> instances to pause operations while the switchover
is being carried out, to prevent <application>repmgrd</application> from
unintentionally promoting a node. For more details, see <xref linkend="repmgrd-pausing">.
</para>
<para>
&repmgr; will not perform the switchover if an exclusive backup is running on the current primary.
Users of &repmgr; versions prior to 4.2 should ensure that <application>repmgrd</application>
is not running on any nodes while a switchover is being executed.
</para>
</note>
@@ -61,8 +68,9 @@
<term><option>--always-promote</option></term>
<listitem>
<para>
Promote standby to primary, even if it is behind original primary
(original primary will be shut down in any case).
Promote standby to primary, even if it is behind or has diverged
from the original primary. The original primary will be shut down in any case,
and will need to be manually reintegrated into the replication cluster.
</para>
</listitem>
</varlistentry>
@@ -122,6 +130,21 @@
</listitem>
</varlistentry>
<varlistentry>
<term><option>--repmgrd-no-pause</option></term>
<listitem>
<para>
Don't pause <application>repmgrd</application> while executing a switchover.
</para>
<para>
This option should not be used unless you take steps by other means
to ensure <application>repmgrd</application> is paused or not
running on all nodes.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--siblings-follow</option></term>
<listitem>

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doc/repmgr.sgml
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@@ -86,6 +86,7 @@
&repmgrd-cascading-replication;
&repmgrd-network-split;
&repmgrd-witness-server;
&repmgrd-pausing;
&repmgrd-degraded-monitoring;
&repmgrd-monitoring;
&repmgrd-bdr;
@@ -112,6 +113,9 @@
&repmgr-cluster-crosscheck;
&repmgr-cluster-event;
&repmgr-cluster-cleanup;
&repmgr-daemon-status;
&repmgr-daemon-pause;
&repmgr-daemon-unpause;
</part>
&appendix-release-notes;

169
doc/repmgrd-pausing.sgml Normal file
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@@ -0,0 +1,169 @@
<chapter id="repmgrd-pausing" xreflabel="Pausing repmgrd">
<indexterm>
<primary>repmgrd</primary>
<secondary>pausing</secondary>
</indexterm>
<indexterm>
<primary>pausing repmgrd</primary>
</indexterm>
<title>Pausing repmgrd</title>
<para>
In normal operation, <application>repmgrd</application> monitors the state of the
PostgreSQL node it is running on, and will take appropriate action if problems
are detected, e.g. (if so configured) promote the node to primary, if the existing
primary has been determined as failed.
</para>
<para>
However, <application>repmgrd</application> is unable to distinguish between
planned outages (such as performing a <link linkend="performing-switchover">switchover</link>
or upgrading a server), and an actual server outage. In versions prior to &repmgr; 4.2
it was necessary to stop <application>repmgrd</application> on all nodes (or at least
on all nodes where <application>repmgrd</application> is
<link linkend="repmgrd-automatic-failover">configured for automatic failover</link>)
to prevent <application>repmgrd</application> from making changes to the
replication cluster.
</para>
<para>
From <link linkend="release-4.2">&repmgr; 4.2</link>, <application>repmgrd</application>
can now be &quot;paused&quot;, i.e. instructed not to take any action such as performing a failover.
This can be done from any node in the cluster, removing the need to stop/restart
each <application>repmgrd</application> individually.
</para>
<sect1 id="repmgrd-pausing-prerequisites">
<title>Prerequisites for pausing <application>repmgrd</application></title>
<para>
In order to be able to pause/unpause <application>repmgrd</application>, following
prerequisites must be met:
<itemizedlist spacing="compact" mark="bullet">
<listitem>
<simpara><link linkend="release-4.2">&repmgr; 4.2</link> or later must be installed on all nodes.</simpara>
</listitem>
<listitem>
<simpara>The same major &repmgr; version (e.g. 4.2) must be installed on all nodes (and preferably the same minor version).</simpara>
</listitem>
<listitem>
<simpara>
PostgreSQL on all nodes must be accessible from the node where the
<literal>pause</literal>/<literal>unpause</literal> operation is executed, using the
<varname>conninfo</varname> string shown by <link linkend="repmgr-cluster-show"><command>repmgr cluster show</command></link>.
</simpara>
</listitem>
</itemizedlist>
</para>
<note>
<para>
These conditions are required for normal &repmgr; operation in any case.
</para>
</note>
</sect1>
<sect1 id="repmgrd-pausing-execution">
<title>Pausing/unpausing <application>repmgrd</application></title>
<para>
To pause <application>repmgrd</application>, execute <link linkend="repmgr-daemon-pause"><command>repmgr daemon pause</command></link>, e.g.:
<programlisting>
$ repmgr -f /etc/repmgr.conf daemon pause
NOTICE: node 1 (node1) paused
NOTICE: node 2 (node2) paused
NOTICE: node 3 (node3) paused</programlisting>
</para>
<para>
The state of <application>repmgrd</application> on each node can be checked with
<link linkend="repmgr-daemon-status"><command>repmgr daemon status</command></link>, e.g.:
<programlisting>$ repmgr -f /etc/repmgr.conf daemon status
ID | Name | Role | Status | repmgrd | PID | Paused?
----+-------+---------+---------+---------+------+---------
1 | node1 | primary | running | running | 7851 | yes
2 | node2 | standby | running | running | 7889 | yes
3 | node3 | standby | running | running | 7918 | yes</programlisting>
</para>
<note>
<para>
If executing a switchover with <link linkend="repmgr-standby-switchover"><command>repmgr standby switchover</command></link>,
&repmgr; will automatically pause/unpause <application>repmgrd</application> as part of the switchover process.
</para>
</note>
<para>
If the primary (in this example, <literal>node1</literal>) is stopped, <application>repmgrd</application>
running on one of the standbys (here: <literal>node2</literal>) will react like this:
<programlisting>
[2018-09-20 12:22:21] [WARNING] unable to connect to upstream node "node1" (node ID: 1)
[2018-09-20 12:22:21] [INFO] checking state of node 1, 1 of 5 attempts
[2018-09-20 12:22:21] [INFO] sleeping 1 seconds until next reconnection attempt
...
[2018-09-20 12:22:24] [INFO] sleeping 1 seconds until next reconnection attempt
[2018-09-20 12:22:25] [INFO] checking state of node 1, 5 of 5 attempts
[2018-09-20 12:22:25] [WARNING] unable to reconnect to node 1 after 5 attempts
[2018-09-20 12:22:25] [NOTICE] node is paused
[2018-09-20 12:22:33] [INFO] node "node2" (node ID: 2) monitoring upstream node "node1" (node ID: 1) in degraded state
[2018-09-20 12:22:33] [DETAIL] repmgrd paused by administrator
[2018-09-20 12:22:33] [HINT] execute "repmgr daemon unpause" to resume normal failover mode</programlisting>
</para>
<para>
If the primary becomes available again (e.g. following a software upgrade), <application>repmgrd</application>
will automatically reconnect, e.g.:
<programlisting>
[2018-09-20 13:12:41] [NOTICE] reconnected to upstream node 1 after 8 seconds, resuming monitoring</programlisting>
</para>
<para>
To unpause <application>repmgrd</application>, execute <link linkend="repmgr-daemon-unpause"><command>repmgr daemon unpause</command></link>, e.g.:
<programlisting>
$ repmgr -f /etc/repmgr.conf daemon pause
NOTICE: node 1 (node1) unpaused
NOTICE: node 2 (node2) unpaused
NOTICE: node 3 (node3) unpaused</programlisting>
</para>
<note>
<para>
If the previous primary is no longer accessible when <application>repmgrd</application>
is unpaused, no failover action will be taken. Instead, a new primary must be manually promoted using
<link linkend="repmgr-standby-promote"><command>repmgr standby promote</command></link>,
and any standbys attached to the new primary with
<link linkend="repmgr-standby-follow"><command>repmgr standby follow</command></link>.
</para>
<para>
This is to prevent <link linkend="repmgr-daemon-unpause"><command>repmgr daemon unpause</command></link>
resulting in the automatic promotion of a new primary, which may be a problem particularly
in larger clusters, where <application>repmgrd</application> could select a different promotion
candidate to the one intended by the administrator.
</para>
</note>
<sect2 id="repmgrd-pausing-details">
<title>Details on the <application>repmgrd</application> pausing mechanism</title>
<para>
The pause state of each node will be stored over a PostgreSQL restart.
</para>
<para>
<link linkend="repmgr-daemon-pause"><command>repmgr daemon pause</command></link> and
<link linkend="repmgr-daemon-unpause"><command>repmgr daemon unpause</command></link> can be
executed even if <application>repmgrd</application> is not running; in this case,
<application>repmgrd</application> will start up in whichever pause state has been set.
</para>
<note>
<para>
<link linkend="repmgr-daemon-pause"><command>repmgr daemon pause</command></link> and
<link linkend="repmgr-daemon-unpause"><command>repmgr daemon unpause</command></link>
<emphasis>do not</emphasis> stop/start <application>repmgrd</application>.
</para>
</note>
</sect2>
</sect1>
</chapter>

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@@ -19,9 +19,10 @@
</para>
<para>
<command>repmgr standby switchover</command> differs from other &repmgr;
actions in that it also performs actions on another server (the demotion
candidate), which means passwordless SSH access is required to that server
from the one where <command>repmgr standby switchover</command> is executed.
actions in that it also performs actions on other servers (the demotion
candidate, and optionally any other servers which are to follow the new primary),
which means passwordless SSH access is required to those servers from the one where
<command>repmgr standby switchover</command> is executed.
</para>
<note>
<simpara>
@@ -153,12 +154,18 @@
manually with <command>repmgr node check --archive-ready</command>.
</para>
<note>
<para>
Ensure that <application>repmgrd</application> is *not* running anywhere to prevent it unintentionally
promoting a node. This restriction will be removed in a future &repmgr; version.
</para>
</note>
<note>
<para>
From <link linkend="release-4.2">repmgr 4.2</link>, &repmgr; will instruct any running
<application>repmgrd</application> instances to pause operations while the switchover
is being carried out, to prevent <application>repmgrd</application> from
unintentionally promoting a node. For more details, see <xref linkend="repmgrd-pausing">.
</para>
<para>
Users of &repmgr; versions prior to 4.2 should ensure that <application>repmgrd</application>
is not running on any nodes while a switchover is being executed.
</para>
</note>
<para>
@@ -303,7 +310,21 @@
2 | node2 | primary | * running | | default | host=node2 dbname=repmgr user=repmgr
</programlisting>
</para>
<para>
If <application>repmgrd</application> is in use, it's worth double-checking that
all nodes are unpaused by executing <command><link linkend="repmgr-daemon-status">repmgr-daemon-status</link></command>.
</para>
<note>
<para>
Users of &repmgr; versions prior to 4.2 will need to manually restart <application>repmgrd</application>
on all nodes after the switchover is completed.
</para>
</note>
</sect1>
<sect1 id="switchover-caveats" xreflabel="Caveats">
<indexterm>
<primary>switchover</primary>
@@ -329,18 +350,8 @@
for details.
</simpara>
</listitem>
<listitem>
<simpara>
<application>repmgrd</application> should not be running with setting <varname>failover=automatic</varname>
in <filename>repmgr.conf</filename> when a switchover is carried out, otherwise the
<application>repmgrd</application> daemon may try and promote a standby by itself.
</simpara>
</listitem>
</itemizedlist>
</para>
<para>
We hope to remove some of these restrictions in future versions of &repmgr;.
</para>
</sect1>
<sect1 id="switchover-troubleshooting" xreflabel="Troubleshooting">