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MariaDB Galera Cluster
Introduction
This is a guide for configuring a 3 node MariaDB Galera Cluster.
A MariaDB Galera cluster requires a minimal of 3 nodes.
However, one of the members of the cluster can be an arbitrator (2 node + 1 arbitrator). Despite not participating in data replication, the arbitrator still needs to be on a 3rd physical node.
[1]
Design
The Maria Galera Cluster is multi master cluster featuring synchronous writes across all nodes. Each node requires a static IP address to function.
If you have a local dns server, you can make use of that. else make use of your hosts file. This will make your system clear about the other nodes and ip address.
/etc/hostsadd you hostname if you don't have it127.0.0.1 localhost 192.168.10.11 node01 192.168.10.12 node02 192.168.10.13 node03
Packages
Add the galera useflag to MariaDB:
/etc/portage/package.useenable galera replication supportdev-db/mariadb galera
Add the garbd useflag (only) on the arbitrator. If you have 3 nodes you can skip this useflag.
/etc/portage/package.useadd this extra useflagsys-cluster/galera garbd
Then, emerge the following packages:
root #emerge --ask dev-db/mariadb sys-cluster/galera
USE flags for sys-cluster/galera Synchronous multi-master replication engine that provides the wsrep API
Database Initialization
Run this command and keyin your mariadb root password
root #emerge --config dev-db/mariadbConfiguring pkg...
* Please provide a password for the mysql 'root' user now
* or through the /root/.my.cnf file.
* Avoid ["'\_%] characters in the password
>
* Retype the password
>
* Creating the mysql database and setting proper
* permissions on it ...
* Command: '/usr/share/mysql/scripts/mysql_install_db' [ ok ]
* Setting root password ... [ ok ]
* Loading "zoneinfo", this step may require a few seconds ... ... [ ok ]
* Stopping the server ...
* Done
Setup Mariadb and Galera
Node01
/etc/mysql/my.cnfMake the change below# Listen on (IPv4) all interfaces bind-address = 0.0.0.0 # unique per-node id, greater than 0 server-id = 1 wsrep_on wsrep_provider=/usr/lib/galera/libgalera_smm.so # You should change this name to something meaningful wsrep_cluster_name="my_mariadb_cluster" # List all nodes of the cluster including this one wsrep_cluster_address="gcomm://192.168.10.11,192.168.10.12,192.168.10.13" # We will come back to change this again later wsrep_sst_method=rsync # Galera Node Configuration wsrep_node_address="192.168.10.11" wsrep_node_name="node01"
Node02
/etc/mysql/my.cnfMake the change below# Listen on (IPv4) all interfaces bind-address = 0.0.0.0 # unique per-node id, greater than 0 server-id = 2 wsrep_on wsrep_provider=/usr/lib/galera/libgalera_smm.so # You should change this name to something meaningful wsrep_cluster_name="my_mariadb_cluster" # List all nodes of the cluster including this one wsrep_cluster_address="gcomm://192.168.10.11,192.168.10.12,192.168.10.13" # We will come back to change this again later wsrep_sst_method=rsync # Galera Node Configuration wsrep_node_address="192.168.10.12" wsrep_node_name="node02"
Node03
/etc/mysql/my.cnfMake the change below# Listen on (IPv4) all interfaces bind-address = 0.0.0.0 # unique per-node id, greater than 0 server-id = 3 wsrep_on wsrep_provider=/usr/lib/galera/libgalera_smm.so # You should change this name to something meaningful wsrep_cluster_name="my_mariadb_cluster" # List all nodes of the cluster including this one wsrep_cluster_address="gcomm://192.168.10.11,192.168.10.12,192.168.10.13" # We will come back to change this again later wsrep_sst_method=rsync # Galera Node Configuration wsrep_node_address="192.168.10.13" wsrep_node_name="node03"
Start mariadb on the first node
When a node starts, by default it assumes that the cluster is already initialised and tries to join it. If no node is initialised, the cluster will not be able to start since all nodes will just try to join a (non) existing cluster. Therefore, the first node in the cluster to be online needs to be instructed to become a "new" cluster (read into STARTING THE FIRST CLUSTER NODE for more defaults):
root #/etc/init.d/mysql bootstrap_galera
Start mariadb on other nodes
root #/etc/init.d/mysql startChecking if all nodes have joined and are running correctly
Try to run this command on node 1:
root #mysql -u root -pEnter password: Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 1102 Server version: 10.1.29-MariaDB Source distribution Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> SHOW STATUS LIKE 'wsrep%'; # Focus on the 2 values below. | wsrep_cluster_size | 3 | | wsrep_ready | ON |
If the cluster size is equal to you node size you are good to go. And wsrep_ready meant the cluster is ON.
Garbd Arbitrator Configuration
This is still a physical 3 node, just not running mariadb.
While the Galera Arbitrator does not participate in replication, it does receive the same data as all other nodes. You must secure its network connection.[1]
Unless this has been fixed in your installation, garbd does not work when specifying cluster address without the port. Make sure to include the port numbers as shown below.
/etc/conf.d/garbdMake the change below# A space-separated list of node addresses (address[:port]) in the cluster GALERA_NODES="192.168.0.10:4567 192.168.0.11:4567" # Galera cluster name, should be the same as on the rest of the nodes. GALERA_GROUP="my_mariadb_cluster"
Not idea why, but cannot turn on Log or it will not start
root #/etc/init.d/garbd startFinalize configuration
The Mariadb cluster should now be up.
Start mariadb on boot
For openrc, do:
root #rc-update add mysql default* service mysql added to runlevel default
Secure mariadb
Secure your mariadb for production use
root #mysql_secure_installation