galera安装文件我们可以在官网下载：http://galeracluster.com/products/ 如果之前服务器上装过mysql需要先卸载，先检测一下有没有：yum list installed | grep mysql 卸载： yum -y remove mysql-libs.x86_64。
然后将下载下来的文件上传之服务器，就可以安装了，和mysql一样也是有依赖关系的，安装顺序不要乱，先看一下文件（由于我的系统是刚安装的所以会缺少些文件）：
[root@testone ~]# ls
galera-3-25.3.22-2.el7.x86_64.rpm mysql-wsrep-client-5.7-5.7.20-25.13.el7.x86_64.rpm mysql-wsrep-devel-5.7-5.7.20-25.13.el7.x86_64.rpm mysql-wsrep-libs-compat-5.7-5.7.20-25.13.el7.x86_64.rpm mysql-wsrep-test-5.7-5.7.20-25.13.el7.x86_64.rpm
mysql-wsrep-5.7-5.7.20-25.13.el7.x86_64.rpm mysql-wsrep-common-5.7-5.7.20-25.13.el7.x86_64.rpm mysql-wsrep-libs-5.7-5.7.20-25.13.el7.x86_64.rpm mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64.rpm现在开始安装：
[root@testone ~]# rpm -ivh mysql-wsrep-common-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-common-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
file /usr/share/mysql/czech/errmsg.sys from install of mysql-wsrep-common-5.7-5.7.20-25.13.el7.x86_64 conflicts with file from package mariadb-libs-1:5.5.56-2.el7.x86_64安装的文件和系统现有的有冲突，搜到这个有冲突的库，卸载掉然后再安装：
[root@testone ~]# rpm -qa| grep mariadb
mariadb-libs-5.5.56-2.el7.x86_64
[root@testone ~]# rpm -e --nodeps mariadb-libs-5.5.56-2.el7.x86_64
[root@testone ~]# rpm -ivh mysql-wsrep-common-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-common-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:mysql-wsrep-common-5.7-5.7.20-25.################################# [100%]可以看到，这次安装成功了，继续：
[root@testone ~]# rpm -ivh mysql-wsrep-libs-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-libs-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:mysql-wsrep-libs-5.7-5.7.20-25.13################################# [100%][root@testone ~]# rpm -ivh mysql-wsrep-client-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-client-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:mysql-wsrep-client-5.7-5.7.20-25.################################# [100%][root@testone ~]# rpm -ivh mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
错误：依赖检测失败：
/usr/bin/perl 被 mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64 需要
lsof 被 mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64 需要
perl(Getopt::Long) 被 mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64 需要
perl(strict) 被 mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64 需要
socat 被 mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64 需要这次又失败了，少些依赖文件，我们用yum安装一下：yum -y install lsof && yum -y install socat && yum -y install perl 也可以一次合起来写，将这三个文件安装好后就可以继续安装了：
[root@testone ~]# rpm -ivh mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-server-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:mysql-wsrep-server-5.7-5.7.20-25.################################# [100%][root@testone ~]# rpm -ivh mysql-wsrep-libs-compat-5.7-5.7.20-25.13.el7.x86_64.rpm
警告：mysql-wsrep-libs-compat-5.7-5.7.20-25.13.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:mysql-wsrep-libs-compat-5.7-5.7.2################################# [100%][root@testone ~]# rpm -ivh galera-3-25.3.22-2.el7.x86_64.rpm
警告：galera-3-25.3.22-2.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
错误：依赖检测失败：
libboost_program_options.so.1.53.0()(64bit) 被 galera-3-25.3.22-2.el7.x86_64 需要安装最后一个时，又失败了还是少依赖文件，yum安装一下：yum -y install boost-devel 然后再次安装：
[root@testone ~]# rpm -ivh galera-3-25.3.22-2.el7.x86_64.rpm
警告：galera-3-25.3.22-2.el7.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID bc19ddba: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:galera-3-25.3.22-2.el7 ################################# [100%]好，安装完毕！接下来我们就开始编写配置文件了：vi /etc/my.cnf 将里面的内容全部注释掉，然后输入： !includedir /etc/my.cnf.d/ 。接下来创建wsrep.cnf文件： vi /etc/my.cnf.d/wsrep.cnf 然后输入根据自己的需求输入配置信息：
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# *** upgrade to a newer version of MySQL.
[mysqld]
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
# These are commonly set, remove the # and set as required.
# basedir = .....
# datadir = .....
# port = .....
# server_id = .....
# socket = .....
log_timestamps=SYSTEM #这个是我们自己加的，防止日志时间和系统时间不一样
port=3306
server_id=11 #MySQL服务器的ID，必须是唯一的，集群各个节点也不同
explicit_defaults_for_timestamp=true
basedir=/usr/local/mysql
datadir=/usr/local/mysql/data
socket=/usr/local/mysql/data/mysql.sock
pid_file=/run/mysqld/mysqld.pid
log_error=/var/log/mysql.error
wsrep_cluster_name='cs_cluster' #galera集群的名字，必须是统一的
wsrep-provider=/usr/lib64/galera-3/libgalera_smm.so #wsrep提供者,必须配置(.so文件的路径在哪，就配置成哪,一般安装好后都是在这个目录下)
wsrep_node_name = node1 #wsrep节点的ID，必须是唯一的，集群各个节点也不同
wsrep_cluster_address=gcomm://192.168.56.11,192.168.56.12,192.168.56.13 #集群中的其他节点地址，可以使用主机名或IP
wsrep_node_address='192.168.56.11' #本机节点地址，可以使用主机名或IP
wsrep_provider_options ="gmcast.listen_addr=tcp://192.168.56.11:4567" #指定wsrep启动端口号,4567为默认值
wsrep_sst_donor='node1,node2,node3' #一个逗号分割的节点串作为状态转移源，比如wsrep_sst_donor=node1,node2,node3 如果node1可用，用node2,如果node2不可用，用node3，最后的逗号表明让提供商自己选择一个最优的。
wsrep_sst_method=rsync #集群同步方式，我的系统没有可以用yum安装一下这个远程连接 yum -y install rsync
wsrep_sst_auth=test:123456 #集群同步的用户名密码
slow_query_log=on
[client]
default-character-set=utf8
socket=/usr/local/mysql/data/mysql.sock
[mysql]
default-character-set=utf8
socket=/usr/local/mysql/data/mysql.sock
[mysqldump]
max_allowed_packet = 512M
[mysqld_safe]
malloc-lib=/usr/lib64/libjemalloc.so.1 #这个我的系统里也没有可以用yum安装一下 yum -y install jemalloc 如果获取不到的话，下载一个数据源 rpm -ivh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm编辑好配置文件就可以初始化数据库了：
[root@testone etc]# mysqld --initialize --user=mysql
mysqld: Can't create directory '/usr/local/mysql/data/' (Errcode: 2 - No such file or directory)
2017-11-19T09:52:36.312857Z 0 [ERROR] Can't find error-message file '/usr/local/mysql/share/mysql/errmsg.sys'. Check error-message file location and 'lc-messages-dir' configuration directive.
2017-11-19T09:52:36.314273Z 0 [ERROR] Aborting出现了两个错误，第一个是无法创建我们制定的文件目录是权限问题mkdir /usr/local/mysql && chown mysql /usr/local/mysql && chgrp mysql /usr/local/mysql 这样就好了，创建一个目录更改一下权限。第二个是在/usr/local/mysql/share/mysql/errmsg.sys目录下找不到文件，这和我们之前配置文件中basedir=/usr/local/mysql有关系，因为basedir指定是数据库的bin，lib之类的文件，我们rpm安装，这些文件默认的路径是在/usr/share/mysql下面，所以basedir这个参数可以不指定也可以，系统会自己找，或者直接指定到/usr/share/mysql/这个目录下面。所以可以将basedir注释掉或者basedir=/usr/ 再次初始化：
[root@testone local]# mysqld --initialize --user=mysql
2017-11-19T10:53:51.701879Z 0 [ERROR] Could not open file '/var/log/mysql.error' for error logging: Permission denied
2017-11-19T10:53:51.701980Z 0 [ERROR] Aborting还是权限问题，创建一个更改下属组，然后就可以了touch /var/log/mysql.error && chown mysql /var/log/mysql.error && chgrp mysql /var/log/mysql.error。初始化后会有一个随机密码在错误日志中我们找一下：
[root@testone log]# grep 'temporary password' /var/log/mysql.error
2017-11-19T10:15:53.600562Z 1 [Note] A temporary password is generated for root@localhost: pq11aelad:Ho然后就启动数据库了，我们先启动第一个节点：
/usr/sbin/mysqld --wsrep-new-cluster --user=mysql &然后输入systemctl status mysqld 发现服务有启动成功，看下报错日志：
2017-11-23T10:56:39.704994+08:00 0 [Warning] Can't create test file /usr/local/mysql/data/testone.lower-test 2017-11-23T10:56:39.705308+08:00 0 [Note] /usr/sbin/mysqld (mysqld 5.7.20-log) starting as process 8784 ... 2017-11-23T10:56:39.707338+08:00 0 [Warning] Can't create test file /usr/local/mysql/data/testone.lower-test 2017-11-23T10:56:39.707363+08:00 0 [Warning] Can't create test file /usr/local/mysql/data/testone.lower-test 2017-11-23T10:56:39.707631+08:00 0 [Note] WSREP: Read nil XID from storage engines, skipping position init 2017-11-23T10:56:39.707641+08:00 0 [Note] WSREP: wsrep_load(): loading provider library '/usr/lib64/galera-3/libgalera_smm.so' 2017-11-23T10:56:39.712123+08:00 0 [Note] WSREP: wsrep_load(): Galera 3.22(r4d7d231) by Codership Oy <info@codership.com> loaded successfully. 2017-11-23T10:56:39.712148+08:00 0 [Note] WSREP: CRC-32C: using hardware acceleration. 2017-11-23T10:56:39.712457+08:00 0 [ERROR] WSREP: Could not open state file for writing: '/usr/local/mysql/data//grastate.dat'. Check permissions and/or disk space.: 13 (Permission denied) at galera/src/saved_state.cpp:SavedState():51 2017-11-23T10:56:39.712467+08:00 0 [ERROR] WSREP: wsrep::init() failed: 7, must shutdown 2017-11-23T10:56:39.712470+08:00 0 [ERROR] Aborting 2017-11-23T10:56:39.712484+08:00 0 [Note] Binlog end 2017-11-23T10:56:39.712536+08:00 0 [Note] /usr/sbin/mysqld: Shutdown complete再网上查了一下这和selinux有关系，实现环境下我们先关闭它还有防火墙setenforce 0 && systemctl stop firewalld再重新输入命令启动一下，发现还是没成功，再看下日志：
2017-11-23T11:25:54.083657+08:00 0 [Warning] WSREP: last inactive check more than PT1.5S ago (PT3.50749S), skipping check
2017-11-23T11:26:23.629382+08:00 0 [Note] WSREP: view((empty))
2017-11-23T11:26:23.629665+08:00 0 [ERROR] WSREP: failed to open gcomm backend connection: 110: failed to reach primary view: 110 (Connection timed out)
at gcomm/src/pc.cpp:connect():158
2017-11-23T11:26:23.629698+08:00 0 [ERROR] WSREP: gcs/src/gcs_core.cpp:gcs_core_open():208: Failed to open backend connection: -110 (Connection timed out)
2017-11-23T11:26:23.630419+08:00 0 [ERROR] WSREP: gcs/src/gcs.cpp:gcs_open():1458: Failed to open channel 'cs_cluster' at 'gcomm://192.168.56.12,192.168.56.13': -110 (Connection timed out)
2017-11-23T11:26:23.630474+08:00 0 [ERROR] WSREP: gcs connect failed: Connection timed out
2017-11-23T11:26:23.630490+08:00 0 [ERROR] WSREP: wsrep::connect(gcomm://192.168.56.12,192.168.56.13) failed: 7
2017-11-23T11:26:23.630498+08:00 0 [ERROR] Aborting
2017-11-23T11:26:23.630514+08:00 0 [Note] Giving 0 client threads a chance to die gracefully
2017-11-23T11:26:23.630529+08:00 0 [Note] WSREP: Service disconnected.
2017-11-23T11:26:24.630860+08:00 0 [Note] WSREP: Some threads may fail to exit.
2017-11-23T11:26:24.630952+08:00 0 [Note] Binlog end
2017-11-23T11:26:24.631085+08:00 0 [Note] /usr/sbin/mysqld: Shutdown complete又去网上搜索了一下，说要将第一个启动节点的配置文件中的wsrep_cluster_address=gcomm://192.168.56.11,192.168.56.12,192.168.56.13 空着。照做后重新启动，等了几秒钟，看下状态：
[root@testone log]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since 四 2017-11-23 11:49:51 CST; 1min 34s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 16855 ExecStartPost=/usr/bin/mysqld_pre_systemd --post (code=exited, status=0/SUCCESS)
Process: 16818 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS $MYSQLD_RECOVER_START (code=exited, status=0/SUCCESS)
Process: 16765 ExecStartPre=/usr/bin/mysqld_pre_systemd --pre (code=exited, status=0/SUCCESS)
Main PID: 16821 (mysqld)
CGroup: /system.slice/mysqld.service
└─16821 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid --wsrep_start_position=00000000-0000-0000-0000-000000000000:-1
11月 23 11:49:45 testone systemd[1]: mysqld.service holdoff time over, scheduling restart.
11月 23 11:49:45 testone systemd[1]: Starting MySQL Server...
11月 23 11:49:51 testone systemd[1]: Started MySQL Server.看样子是起来了，根据日志密码进入数据库后修改密码，添加同步数据的账户，也就是配置文件中我们设置的，更改密码后，我的节点二和三也变了，好像是同步过去的，不过咱们还需要在创建一下，要不然节点一挂掉后，其他用户无法使用了。再看一下节点状态：
[root@testone log]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.20-log
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '666666';
Query OK, 0 rows affected (0.03 sec)
mysql> GRANT ALL PRIVILEGES ON *.* TO 'test'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;FLUSH PRIVILEGES;
Query OK, 0 rows affected, 1 warning (0.01 sec)
Query OK, 0 rows affected (0.00 sec)
mysql> show status like "wsrep%";
+------------------------------+--------------------------------------+
| Variable_name | Value |
+------------------------------+--------------------------------------+
| wsrep_local_state_uuid | 5a2ba584-d001-11e7-ae65-ea5a710753c5 |
| wsrep_protocol_version | 7 |
| wsrep_last_committed | 3 |
| wsrep_replicated | 3 |
| wsrep_replicated_bytes | 701 |
| wsrep_repl_keys | 3 |
| wsrep_repl_keys_bytes | 93 |
| wsrep_repl_data_bytes | 416 |
| wsrep_repl_other_bytes | 0 |
| wsrep_received | 2 |
| wsrep_received_bytes | 142 |
| wsrep_local_commits | 0 |
| wsrep_local_cert_failures | 0 |
| wsrep_local_replays | 0 |
| wsrep_local_send_queue | 0 |
| wsrep_local_send_queue_max | 1 |
| wsrep_local_send_queue_min | 0 |
| wsrep_local_send_queue_avg | 0.000000 |
| wsrep_local_recv_queue | 0 |
| wsrep_local_recv_queue_max | 2 |
| wsrep_local_recv_queue_min | 0 |
| wsrep_local_recv_queue_avg | 0.500000 |
| wsrep_local_cached_downto | 1 |
| wsrep_flow_control_paused_ns | 0 |
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_sent | 0 |
| wsrep_flow_control_recv | 0 |
| wsrep_cert_deps_distance | 1.000000 |
| wsrep_apply_oooe | 0.000000 |
| wsrep_apply_oool | 0.000000 |
| wsrep_apply_window | 1.000000 |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 1.000000 |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
| wsrep_cert_index_size | 1 |
| wsrep_causal_reads | 0 |
| wsrep_cert_interval | 0.000000 |
| wsrep_incoming_addresses | 192.168.56.11:3306 |
| 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_gcomm_uuid | 5a2b5de1-d001-11e7-bbad-e6b3cf84d92e |
| wsrep_cluster_conf_id | 1 |
| wsrep_cluster_size | 1 |
| wsrep_cluster_state_uuid | 5a2ba584-d001-11e7-ae65-ea5a710753c5 |
| wsrep_cluster_status | Primary |
| wsrep_connected | ON |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_index | 0 |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <info@codership.com> |
| wsrep_provider_version | 3.22(r4d7d231) |
| wsrep_ready | ON |
+------------------------------+--------------------------------------+
57 rows in set (0.00 sec)
mysql> quit
Bye成功，再配置启动其他节点，再查看状态就会发现节点个数增加啦！如果在生产环境下，我们需要启用防火墙，那就需要开放一些端口：
sudo firewall-cmd --add-port=3306/tcp --permanent
sudo firewall-cmd --add-port=4567/tcp --permanent
sudo firewall-cmd --add-port=4567/udp --permanent
sudo firewall-cmd --add-port=4568/tcp --permanent
sudo firewall-cmd --add-port=4444/tcp --permanent