From 4fbb18535b74da4b95edc76fe042e4b12b0f10b4 Mon Sep 17 00:00:00 2001 From: Esa Korhonen Date: Fri, 20 Sep 2019 18:30:54 +0300 Subject: [PATCH] MXS-2620 Mention that a normal master server shutdown may lose events --- Documentation/Monitors/MariaDB-Monitor.md | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/Documentation/Monitors/MariaDB-Monitor.md b/Documentation/Monitors/MariaDB-Monitor.md index ec3f4805c..c46ae7821 100644 --- a/Documentation/Monitors/MariaDB-Monitor.md +++ b/Documentation/Monitors/MariaDB-Monitor.md @@ -325,6 +325,9 @@ server. See the section on `handle_server_events` for more information. All cluster operations can be activated manually through MaxAdmin/MaxCtrl. See section [Manual activation](#manual-activation) for more details. +See [Limitations and requirements](#limitations-and-requirements) for +information on possible issues with failover and switchover. + ### Operation details **Failover** replaces a failed master with a running slave. It does the @@ -546,8 +549,14 @@ Failover may lose events. If a master goes down before sending new events to at least one slave, those events are lost when a new master is chosen. If the old master comes back online, the other servers have likely moved on with a diverging history and the old master can no longer join the replication cluster. -To minimize the chance for this happening, use +To reduce the chance for this happening, use [semisynchronous replication](https://mariadb.com/kb/en/library/semisynchronous-replication/). +Even a controlled shutdown of the master may lose events. The server does not by +default wait for all data to be replicated to the slaves when shutting down and +instead simply closes all connections. When shutting down the master with the +intention of having a slave promoted, run *switchover* first to ensure that all +data is replicated. For more information on server shutdown, see +[Binary Log Dump Threads and the Shutdown Process](https://mariadb.com/kb/en/library/replication-threads/#binary-log-dump-threads-and-the-shutdown-process). Switchover requires that the cluster is "frozen" for the duration of the operation. This means that no data modifying statements such as INSERT or UPDATE