Galera能够实现mysql/MariaDB数据库的主主复制和多主复制等模式，这些复制模式都是同步进行的，同步时间非常短。
每一个节点都可以同时写入和读取，当某一节点发生故障时，可自动从集群中自动剔除。
HAProxy能提供负载均衡和故障判断等功能解决服务器系统存在的单点故障。
Keepalived能提供客户端连接数据库时使用的虚拟IP地址（VIP）。
（1）主节点
IP地址：node-1 192.168.1.74
（2）备份节点
IP地址：node-2 192.168.1.75
编辑每个节点/etc/hosts文件，添加所有节点IP地址和主机名
vi /etc/hosts
192.168.1.74 node-1
192.168.1.75 node-2
关闭selinux
vi /etc/selinux/config
SELINUX=permissive
关闭防火墙并设置开机不自启
systemctl stop firewalld
配置yum源文件
vi /etc/yum.repos.d/mariadb.repo
yum clean all
yum list
安装服务（node-1节点和node-2节点）
yum install MariaDB-server galera
修改配置文件
（1）修改/etc/my.cnf,添加以下内容（node-1节点和node-2节点）
vi /etc/my.cnf
[mysqld]
max_connect_errors=1000
（2）配置主节点node-1
vi /etc/my.cnf.d/server.cnf
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address=gcomm://
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0
wsrep_cluster_name="MariaDB_Cluster"
wsrep_node_address="192.168.1.74"
wsrep_sst_method=rsyn
（3）配置备份节点node-2
vi /etc/my.cnf.d/server.cnf
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.1.74,192.168.1.75"
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0
wsrep_cluster_name="MariaDB_Cluster"
wsrep_node_address="192.168.1.75"
wsrep_sst_method=rsync
启动服务
node-1节点：
/bin/galera_new_cluster
node-2节点：
systemctl start mariadb
测试集群状态
（1）查询集群状态
mysql -u root -p
MariaDB [(none)]> show status like \'wsrep_%\';
+------------------------------+---------------------------------------+
| Variable_name | Value |
+------------------------------+---------------------------------------+
| wsrep_apply_oooe | 0.000000 |
| wsrep_apply_oool | 0.000000 |
| wsrep_apply_window | 0.000000 |
| wsrep_causal_reads | 0 |
| wsrep_cert_deps_distance | 0.000000 |
| wsrep_cert_index_size | 0 |
| wsrep_cert_interval | 0.000000 |
| wsrep_cluster_conf_id | 2 |
| wsrep_cluster_size | 2 |
| wsrep_cluster_state_uuid | 841486a3-b56a-11e8-a451-d7d8f2309253 |
| wsrep_cluster_status | Primary |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 0.000000 |
| wsrep_connected | ON |
| wsrep_desync_count | 0 |
| wsrep_evs_delayed | |
| wsrep_evs_evict_list | |
| wsrep_evs_repl_latency | 0/0/0/0/0 |
| wsrep_evs_state | OPERATIONAL |
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_paused_ns | 0 |
| wsrep_flow_control_recv | 0 |
| wsrep_flow_control_sent | 0 |
| wsrep_gcomm_uuid | 8412f980-b56a-11e8-bb08-4fd6339a7674 |
| wsrep_incoming_addresses | 192.168.100.11:3306,192.168.1.74:3306 |
| wsrep_last_committed | 0 |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_cached_downto | 18446744073709551615 |
| wsrep_local_cert_failures | 0 |
| wsrep_local_commits | 0 |
| wsrep_local_index | 1 |
| wsrep_local_recv_queue | 0 |
| wsrep_local_recv_queue_avg | 0.166667 |
| wsrep_local_recv_queue_max | 2 |
| wsrep_local_recv_queue_min | 0 |
| wsrep_local_replays | 0 |
| wsrep_local_send_queue | 0 |
| wsrep_local_send_queue_avg | 0.000000 |
| wsrep_local_send_queue_max | 1 |
| wsrep_local_send_queue_min | 0 |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
| wsrep_local_state_uuid | 841486a3-b56a-11e8-a451-d7d8f2309253 |
| wsrep_protocol_version | 7 |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy info@codership.com |
| wsrep_provider_version | 25.3.22(r3764) |
| wsrep_ready | ON |
| wsrep_received | 6 |
| wsrep_received_bytes | 414 |
| wsrep_repl_data_bytes | 0 |
| wsrep_repl_keys | 0 |
| wsrep_repl_keys_bytes | 0 |
| wsrep_repl_other_bytes | 0 |
| wsrep_replicated | 0 |
| wsrep_replicated_bytes | 0 |
| wsrep_thread_count | 2 |
+------------------------------+---------------------------------------+
58 rows in set (0.00 sec)
如果 "wsrep_local_state_comment" is "Synced" 则表明集群创建成功
（3）数据同步
在node-1上新建数据库galera_test
MariaDB [(none)]> create database galera_test;
MariaDB [(none)]> show databases;
在node-2上查询
MariaDB [(none)]> show databases;
