MariaDB 10.1.1: Galera support

Written by Written by Nirbhay Choubey 2 Comments on MariaDB 10.1.1: Galera support

MariaDB 10.1 server is now “Galera ready” with the latest 10.1.1 release. It includes wsrep (write set replication) patch that enables server to load the wsrep provider (galera) library and interact with it to provide multi-master synchronous replication support. The patch implements hooks inside server and storage engines to populate and apply the write sets on sender and receiver nodes in a cluster respectively. The wsrep patch also adds a number of system and status variables (prefixed with wsrep) that can be used to configure and monitor the server acting as a node in Galera cluster.

Unlike older MariaDB versions, the wsrep patch is now part of regular (vanilla) MariaDB 10.1 server, that is, with 10.1.1 there would be no separate vanilla and Galera server versions. As a result, same 10.1 packages (binary tarballs, deb, rpm, etc.) can now be used to run MariaDB server as standalone server or a node in MariaDB Galera cluster.

As a standalone server, it would require no additional settings, just your usual favorite options. However, if one wants to start it as a MariaDB Galera node the following mandatory settings would be required :

  • wsrep_on=ON
  • wsrep_provider
  • wsrep_cluster_address
  • binlog_format=ROW
  • default_storage_engine=InnoDB
  • innodb_autoinc_lock_mode=2
  • innodb_doublewrite=1
  • query_cache_size=0

Without these additional settings the Galera replication essentially gets disabled and server functions like a standalone server with no Galera-related overhead.

If you are building MariaDB 10.1 server from source, WITH_WSREP cmake switch (ON by default) can be used to control the inclusion of wsrep patch in the build.

MariaDB [test]> select @@version;
+----------------------------+
| @@version                  |
+----------------------------+
| 10.1.1-MariaDB-wsrep-debug |
+----------------------------+
1 row in set (0.00 sec)

MariaDB [test]> show status like 'wsrep_ready';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_ready   | ON    |
+---------------+-------+
1 row in set (0.00 sec)

MariaDB [test]> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 2     |
+--------------------+-------+
1 row in set (0.00 sec)

More about MariaDB Galera cluster: