github/repmgr
1
0
Fork 0
mirror of https://github.com/EnterpriseDB/repmgr.git synced 2026-03-27 00:46:29 +00:00
Code Issues Packages Projects Releases 1 Wiki Activity

Add functionality to "pause" repmgrd

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

49
doc/switchover.sgml
View File

@@ -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">