CLUSTER DB-galera mysql centos7-OK

How to install and configure Galera MySQL cluster on CentOS 7

https://www.linuxhelp.com/how-to-install-and-configure-galera-mysql-cluster-on-centos-7

To install and configure Galera MySQL Cluster on CentOS 7

MariaDB Galera Cluster is a synchronous multi-master cluster for MariaDB. It is available on Linux only, and only supports the XtraDB/InnoDB storage engines. In this tutorial am going install and configure Mariadb cluster 10.0 with 3 nodes on centos 7.

Features

• Synchronous replication
• Active-active multi-master topology
• Read and write to any cluster node
• Automatic membership control, failed nodes drop from the cluster
• Automatic node joining
• True parallel replication, on row level
• Direct client connections, native MariaDB look & feel

Before you begin with the configuration, make sure do the following steps :-

1. Disable the Selinux service.
sestatus
sudo setenforce 0

1. 
   Open the /etc/selinux/config file and set the SELINUX mod to disabled:
   /etc/selinux/config

   # This file controls the state of SELinux on the system.
   # SELINUX= can take one of these three values:
   #       enforcing - SELinux security policy is enforced.
   #       permissive - SELinux prints warnings instead of enforcing.
   #       disabled - No SELinux policy is loaded.
   SELINUX=disabled
   # SELINUXTYPE= can take one of these two values:
   #       targeted - Targeted processes are protected,
   #       mls - Multi Level Security protection.
   SELINUXTYPE=targeted

   Copy
2. Save the file and reboot your CentOS system with:

   sudo shutdown -r now

3. Once the system boots up, verify the change with the sestatus command:

   sestatus

   The output should look like this:

   SELinux status:                 disabled

2. Disable the firewall service.
sudo systemctl stop firewalld
sudo systemctl disable firewalld

Cluster details

Node1 192.168.7.211

Node2 192.168.7.212

Node3 192.168.7.213

Configuring Galera

Remove defaults MariaDB library files for all the three nodes

[root@server1 ~]# yum remove mariadb-libs -y

Once it is removed, create the MariaDB repository file for all three nodes as follows.

[root@server1 ~]# vim /etc/yum.repos.d/cluster.repo

[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/10.0/centos7-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1

Now, install socat dependency package in all the 3 nodes. Use the following command for the same purpose.

[root@server1 ~]# yum install socat

Now is the time to install MariaDB Galera cluster 10.0 and its dependencies packages for all the nodes.

[root@server1 ~]# yum install MariaDB-Galera-server MariaDB-client rsync galera

Once it is installed, start the MariaDB services

[root@server1 ~]# systemctl start mysql

Execute the following commad to set MariaDB root login credential.

[root@server1 ~]# mysql_secure_installation

Now you can stop MariaDB service by running the following command. Do the same for all the three nodes.

[root@server1 ~]# systemctl stop msyql

You can now go on with Galera cluster configuration by adding the cluster address, cluster name, node address, etc. Don' t forget to do the same for the other two nodes as well.

[root@server1 ~]#  vim /etc/my.cnf.d/server.cnf
[mariadb-10.0]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
innodb_locks_unsafe_for_binlog=1
query_cache_size=0
query_cache_type=0
bind-address=0.0.0.0
datadir=/var/lib/mysql
innodb_log_file_size=100M
innodb_file_per_table
innodb_flush_log_at_trx_commit=2
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address=" gcomm://192.168.7.211,192.168.7.212,192.168.7.213" 
wsrep_cluster_name=' galera_cluster' 
wsrep_node_address=' 192.168.7.211' 
wsrep_node_name=' node1' 
wsrep_sst_method=rsync
wsrep_sst_auth=db_user:admin

For configuring this cluster configuration on node2 and node3 do not forget to adjust the wsrep_node_address and wsrep_node_name variables. Before doing this steps stop the mysql service on both nodes.

For node2:

wsrep_node_address=' 192.168.7.212' 
wsrep_node_name=' node2' 

For db3

wsrep_node_address=' 192.168.7.213' 
wsrep_node_name=' node3' 

Once all the nodes are configured, you can start first cluster node.

This command should be executed only on node1.

[root@server1 ~]# /etc/init.d/mysql start &ndash wsrep-new-cluster

After that, sart MySQL service on both node2 and node3 as well. Run the following command on both the remaining nodes.

[root@server1 ~]# systemctl start mysql

Now check the status of configured galera cluster at node1. Repeat this command on node2 and node3 to check

# mysql

MariaDB [(none)]>  show status like ' wsrep%'  

| wsrep_incoming_addresses      | 192.168.7.212:3306,192.168.7.211:3306,192.168.7.213:3306 
 
| wsrep_local_state_comment     | Synced        

| wsrep_cluster_size            | 3                                                        

| wsrep_ready                   | ON          

Now, you can check replication process by creating a database from node1.

> mysql
>  create database sample1_db 
> show schema 

+--------------------+
| Database           |
+--------------------+
| sample1_db         |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+

After that login mysql into node2 and check the replication process there too.

>  show schemas 

+--------------------+
| Database           |
+--------------------+
| sample1_db         |
|                    |
|information_schema  |
| mysql              |
| performance_schema |
+--------------------+

Login mysql into node3 and check the replication process in it as well.

>  schow schemas 

+----------------------------+
| Database                   |
+----------------------------+
| sample1_db                 |
|                            |
|information_schema          |
| mysql                      |
| performance_schema         |
+----------------------------+

If you want to test more repilcatiom proess create a table and insert the values into that DB.

Node1

MariaDB [sample1_db]>  create table os(categories(char(25))) 

MariaDB [sample1_db]>  insert into os values(' Linux' ) 

MariaDB [sample1_db]>  select * from os 
+----------------+
| categories     |
+---------------+
| Linux          |
+----------------+

Node2

MariaDB [sample1_db]>  insert into os values(" MAC" ) 
Query OK, 1 row affected (0.02 sec)

MariaDB [sample1_db]>  select * from os 
+--------------+
| categories   |
+--------------+
| Linux        |
| MAC          |
+--------------+

Node3

MariaDB [sample1_db]>  insert into os values(' Windows' ) 
Query OK, 1 row affected (0.00 sec)

MariaDB [sample1_db]>  select * from os 
+---------------+
| categories    |
+---------------+
| Linux         |
| MAC           |
| Windows       |
+---------------+

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