环境
三台主机
pxc1:192.168.7.71
pxc2:192.168.7.72
pxc3:192.168.7.73
firewalld 和 selinux都关闭，保证时间同步；如果已安装MySQL，必须卸载！！！
OS 版本
[root@pxc1 ~]#cat /etc/redhat-release
CentOS Linux release 7.7.1908 (Core)
操作步骤
pxc1主机
1.安装辅助工具Ansible，前提三台主机做好key验证
[root@pxc1 ~]#yum -y install ansible
1.1/etc/ansible/hosts配置，在最后一行后面添加以下配置
[pxcservers]
192.168.7.71
192.168.7.72
192.168.7.73
1.2/etc/ansible/ansible.cfg配置
module_name = shell #115行，将默认的模块command该为shell
host_key_checking = False #71行，去掉前面的注释
2.安装Percona XtraDB Cluster 5.7
# 1.使用清华大学的yum源，官方源太慢了
[root@pxc1 ~]#vim /etc/yum.repos.d/pxc.repo
[percona]
name=percona_repo
baseurl=https://mirrors.tuna.tsinghua.edu.cn/percona/release/$releasever/RPMS/$basearch
enabled=1
gpgcheck=0
# 2.同时将配置文件传给pxc2和pxc3
[root@pxc1 ~]#ansible 'pxcservers:!192.168.7.71' -m copy -a 'src=/etc/yum.repos.d/pxc.repo dest=/etc/yum.repos.d'
192.168.7.73 | CHANGED => {
# 3.查看三台主机的pxc.repo文件是否一致
[root@pxc1 ~]#ansible 'pxcservers' -a 'cat /etc/yum.repos.d/pxc.repo'
192.168.7.73 | CHANGED | rc=0 >>
[percona]
name=percona_repo
baseurl=https://mirrors.tuna.tsinghua.edu.cn/percona/release/$releasever/RPMS/$basearch
enabled=1
gpgcheck=0
192.168.7.72 | CHANGED | rc=0 >>
[percona]
name=percona_repo
baseurl=https://mirrors.tuna.tsinghua.edu.cn/percona/release/$releasever/RPMS/$basearch
enabled=1
gpgcheck=0
192.168.7.71 | CHANGED | rc=0 >>
[percona]
name=percona_repo
baseurl=https://mirrors.tuna.tsinghua.edu.cn/percona/release/$releasever/RPMS/$basearch
enabled=1
gpgcheck=0
# 4.执行以下命令，在三台主机都安装PXC 5.7
[root@pxc1 ~]#ansible 'pxcservers' -a 'yum install Percona-XtraDB-Cluster-57 -y'
3.修改配置文件
# /etc/my.cnf为主配置文件，当前版本中，其余的配置文件都放在/etc/percona-xtradb-cluster.conf.d目录里，包括mysqld.cnf，mysqld_safe.cnf，wsrep.cnf 三个文件
[root@pxc1 ~]#tree /etc/percona-xtradb-cluster.conf.d/
/etc/percona-xtradb-cluster.conf.d/
├── mysqld.cnf
├── mysqld_safe.cnf
└── wsrep.cnf
0 directories, 3 files
[root@pxc1 ~]#egrep -v "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.7.71,192.168.7.72,192.168.7.73 #集群中每个几点的IP
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.7.71 #取消行首注释，指定本节点的IP
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-1 #本节点在集群中的名称
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:123.com" #取消行首注释，并且修改密码
3.1将配置文件copy给pxc2，pxc3两台主机，然后稍作修改，主要项是wsrep_node_address和wsrep_node_name
# 1.copy
[root@pxc1 ~]#ansible 'pxcservers:!192.168.7.71' -m copy -a 'src=/etc/percona-xtradb-cluster.conf.d/wsrep.cnf dest=/etc/percona-xtradb-cluster.conf.d'
# 2.修改pxc2主机的配置文件
[root@pxc1 ~]#ansible '192.168.7.72' -a 'sed -i -e s/wsrep_node_address=192.168.7.71/wsrep_node_address=192.168.7.72/ -e s/wsrep_node_name=pxc-cluster-node-1/wsrep_node_name=pxc-cluster-node-2/ /etc/percona-xtradb-cluster.conf.d/wsrep.cnf'
# 3.修改pxc3主机的配置文件
[root@pxc1 ~]#ansible '192.168.7.73' -a 'sed -i -e s/wsrep_node_address=192.168.7.71/wsrep_node_address=192.168.7.73/ -e s/wsrep_node_name=pxc-cluster-node-1/wsrep_node_name=pxc-cluster-node-3/ /etc/percona-xtradb-cluster.conf.d/wsrep.cnf'
# 4.查看三个几点的配置文件信息
[root@pxc1 ~]#ansible 'pxcservers' -a 'egrep -v "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf'
[root@pxc1 ~]#ansible 'pxcservers' -a 'egrep -v "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf'
192.168.7.72 | CHANGED | rc=0 >>
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.7.71,192.168.7.72,192.168.7.73
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.7.72
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-2
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:123.com"
192.168.7.73 | CHANGED | rc=0 >>
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.7.71,192.168.7.72,192.168.7.73
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.7.73
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-3
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:123.com"
192.168.7.71 | CHANGED | rc=0 >>
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.7.71,192.168.7.72,192.168.7.73
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.7.71
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-1
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:123.com"
注：尽管Galera Cluster不再需要通过binlog的形式进行同步，但还是建议在配置文件中开启二进制日志功能，原因是后期如果有新节点需要加入，老节点通过SST全量传输的方式向新节点传输数据，很可能会拖垮集群性能，所以让新节点先通过binlog方式完成同步后再加入集群会是一种更好的选择
4.启动集群中的第一个节点
[root@pxc1 ~]#systemctl start [email protected]
[root@pxc1 ~]#systemctl enable [email protected]
# PXC最常使用的端口号如下，其中3306、4567启动的时候就会监听
4567：组成员之间进行沟通的端口号
3306：数据库对外服务的端口号
4444：请求SST的端口号
4568：用于传输IST的端口号
5.修改初始化密码，并且创建及授权sstuser用户
[root@pxc1 ~]#mysql -p`awk /root@localhost/'{print $NF}' /var/log/mysqld.log`
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 22
Server version: 5.7.27-30-57-log
Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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 '123.com';
Query OK, 0 rows affected (0.01 sec)
mysql> create user 'sstuser'@'localhost' identified by '123.com';
Query OK, 0 rows affected (0.01 sec)
mysql> grant reload,lock tables,process,replication client on *.* to 'sstuser'@'localhost';
Query OK, 0 rows affected (0.00 sec)
6.查看相关的状态变量
mysql> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 1 |
+--------------------+-------+
1 row in set (0.01 sec)
# 表示该Galera集群中只有一个节点
mysql> show status like 'wsrep_cluster_status';
+----------------------+---------+
| Variable_name | Value |
+----------------------+---------+
| wsrep_cluster_status | Primary |
+----------------------+---------+
1 row in set (0.00 sec)
# 表示该节点在集群中的状态为Primary，且已经完全连接并准备好
mysql> show status like 'wsrep_local_state%';
+---------------------------+--------------------------------------+
| Variable_name | Value |
+---------------------------+--------------------------------------+
| wsrep_local_state_uuid | b0fdc391-156e-11ea-89de-331ca2945d2c |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
+---------------------------+--------------------------------------+
3 rows in set (0.00 sec)
#状态为Synced(4)，表示数据已同步完成(因为是第一个引导节点，无数据需要同步)。 如果状态是Joiner, 意味着 SST 没有完成. 只有所有节点状态是Synced，才可以加新节点
7.启动PXC集群中pxc2,pxc3节点
[root@pxc1 ~]#ansible 'pxcservers:!192.168.7.71' -a 'systemctl enable --now mysql'
pxc2主机
8.查看集群状态，验证集群是否成功（也可以是其它任意节点）
[root@pxc2 ~]#mysql -p123.com
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39
Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> show variables like 'wsrep_node_name';
+-----------------+--------------------+
| Variable_name | Value |
+-----------------+--------------------+
| wsrep_node_name | pxc-cluster-node-2 |
+-----------------+--------------------+
1 row in set (0.01 sec)
mysql> show variables like 'wsrep_node_address';
+--------------------+--------------+
| Variable_name | Value |
+--------------------+--------------+
| wsrep_node_address | 192.168.7.72 |
+--------------------+--------------+
1 row in set (0.00 sec)
mysql> show variables like 'wsrep_on';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_on | ON |
+---------------+-------+
1 row in set (0.00 sec)
mysql> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 3 |
+--------------------+-------+
1 row in set (0.00 sec)
pxc3主机
9.创建数据库（也可以是其它任意节点）
# 查看当前的数据库
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
# 创建db1数据库
[root@pxc1 ~]#ansible '192.168.7.73' -a 'mysql -p123.com -e "create database db1;\n"'
192.168.7.73 | CHANGED | rc=0 >>
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
# 查看集群中的其它节点是否同步新建的db1数据库
[root@pxc1 ~]#ansible 'pxcservers' -a 'mysql -p123.com -e "show databases\n"'
192.168.7.73 | CHANGED | rc=0 >>
PAGER set to stdout
Database
information_schema
db1
mysql
performance_schema
sysmysql: [Warning] Using a password on the command line interface can be insecure.
192.168.7.72 | CHANGED | rc=0 >>
PAGER set to stdout
Database
information_schema
db1
mysql
performance_schema
sysmysql: [Warning] Using a password on the command line interface can be insecure.
192.168.7.71 | CHANGED | rc=0 >>
PAGER set to stdout
Database
information_schema
db1
mysql
performance_schema
sysmysql: [Warning] Using a password on the command line interface can be insecure.
10.在集群中的所有节点同时创建db2数据库，只有一个节点会成功
[root@pxc1 ~]#ansible 'pxcservers' -a 'mysql -p123.com -e "create database db2\n"'
192.168.7.73 | FAILED | rc=1 >>
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1007 (HY000) at line 1: Can't create database 'db2'; database existsnon-zero return code
192.168.7.72 | CHANGED | rc=0 >>
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
192.168.7.71 | FAILED | rc=1 >>
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1007 (HY000) at line 1: Can't create database 'db2'; database existsnon-zero return code
在PXC集群中加入节点
一个节点加入到Galera集群有两种情况：新节点加入集群、暂时离组的成员再次加入集群
1）节点加入Galera集群
新节点加入集群时，需要从当前集群中选择一个Donor节点来同步数据，也就是所谓的
state_snapshot_tranfer(SST)过程。SST同步数据的方式由选项wsrep_sst_method决定，一般选择的是xtrabackup。必须注意，新节点加入Galera时，会删除新节点上所有已有数据，再通过xtrabackup(假设使用的是该方式)从Donor处完整备份所有数据进行恢复。所以，如果数据量很大，新节点加入过程会很慢。而且，在一个新节点成为Synced状态之前，不要同时加入其它新节点，否则很容易将集群压垮。
如果是这种情况，可以考虑使用wsrep_sst_method=rsync来做增量同步，既然是增量同步，最好保证新节点上已经有一部分数据基础，否则和全量同步没什么区别，且这样会对Donor节点加上全局read only锁。
2）旧节点加入Galera集群
如果旧节点加入Galera集群，说明这个节点在之前已经在Galera集群中呆过，有一部分数据基础，缺少的只是它离开集群时的数据。这时加入集群时，会采用IST(incremental snapshot transfer)传输机制，即使用增量传输。
但注意，这部分增量传输的数据源是Donor上缓存在GCache文件中的，这个文件有大小限制，如果缺失的数据范围超过已缓存的内容，则自动转为SST传输。如果旧节点上的数据和Donor上的数据不匹配(例如这个节点离组后人为修改了一点数据)，则自动转为SST传输。
11.在PXC集群中再加一台新的主机PXC4：192.168.7.74
11.1安装
# 先在ansible主控机的hosts文件中添加192.168.7.74，然后执行以下操作
[root@pxc1 ~]#ansible '192.168.7.74' -m copy -a 'src=/etc/yum.repos.d/pxc.repo dest=/etc/yum.repos.d'
[root@pxc1 ~]#ansible '192.168.7.74' -a 'yum -y install Percona-XtraDB-Cluster-57'
[root@pxc1 ~]#ansible '192.168.7.74' -m copy -a 'src=/etc/percona-xtradb-cluster.conf.d/wsrep.cnf dest=/etc/percona-xtradb-cluster.conf.d'
[root@pxc1 ~]#ansible '192.168.7.74' -a 'sed -i -e s/wsrep_node_address=192.168.7.71/wsrep_node_address=192.168.7.74/ -e s/wsrep_node_name=pxc-cluster-node-1/wsrep_node_name=pxc-cluster-node-4/ /etc/percona-xtradb-cluster.conf.d/wsrep.cnf'
[root@pxc1 ~]#ansible 192.168.7.74 -a "sed -i 's/^wsrep_cluster_address.*/&,192.168.7.74/' /etc/percona-xtradb-cluster.conf.d/wsrep.cnf"
[root@pxc1 ~]#ansible 192.168.7.74 -a 'egrep -v "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf'
192.168.7.74 | CHANGED | rc=0 >>
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.7.71,192.168.7.72,192.168.7.73,192.168.7.74
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.7.74
wsrep_cluster_name=pxc-cluster
wsrep_node_name=pxc-cluster-node-4
pxc_strict_mode=ENFORCING
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:123.com"
11.2启动
[root@pxc1 ~]#ansible 192.168.7.74 -a 'systemctl enable --now mysql'
11.3在新加入的节点中查看集群状态
[root@pxc4 ~]#mysql -p123.com
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39
Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 4 |
+--------------------+-------+
1 row in set (0.01 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| db1 |
| db2 |
| mysql |
| performance_schema |
| sys |
+--------------------+
6 rows in set (0.00 sec)
修改集群中其它节点的配置文件，将新加入的节点添加到配置文件中
[root@pxc1 ~]#ansible 'pxcservers:!192.168.7.74' -a "sed -i 's/^wsrep_cluster_address.*/&,192.168.7.74/' /etc/percona-xtradb-cluster.conf.d/wsrep.cnf"
在PXC集群中修复故障节点
12.停止集群中任意节点的mysql服务，这里停止pxc2
[root@pxc1 ~]#ansible 192.168.7.72 -a 'systemctl stop mysql'
13.在集群中的其它任意节点（这里在pxc3）查看wsrep_cluster_size变量少了一个节点
[root@pxc3 ~]#mysql -p123.com
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 13
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39
Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> show status like 'wrep_cluster_size';
Empty set (0.00 sec)
mysql> show status like 'wrep_cluster_size';
Empty set (0.00 sec)
mysql> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 3 |
+--------------------+-------+
1 row in set (0.00 sec)
14.在集群中的其它任意节点创建db3数据库（这里在pxc4），然后查看其它节点是否同步数据
[root@pxc4 ~]#mysql -p123.com
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 5.7.27-30-57-log Percona XtraDB Cluster (GPL), Release rel30, Revision 64987d4, WSREP version 31.39, wsrep_31.39
Copyright (c) 2009-2019 Percona LLC and/or its affiliates
Copyright (c) 2000, 2019, 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> create database db3;
Query OK, 1 row affected (0.01 sec)
[root@pxc1 ~]#ansible pxcservers -a 'mysql -p123.com -e "show databases;\n"'
192.168.7.73 | CHANGED | rc=0 >>
Database
information_schema
db1
db2
db3
mysql
performance_schema
sys
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
192.168.7.72 | FAILED | rc=1 >>
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)non-zero return code
192.168.7.74 | CHANGED | rc=0 >>
Database
information_schema
db1
db2
db3
mysql
performance_schema
sys
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
192.168.7.71 | CHANGED | rc=0 >>
Database
information_schema
db1
db2
db3
mysql
performance_schema
sys
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.
15.恢复pxc2的mysql服务，数据同步
[root@pxc1 ~]#ansible 192.168.7.72 -a 'systemctl start mysql'
192.168.7.72 | CHANGED | rc=0 >>
[root@pxc1 ~]#ansible 192.168.7.72 -a 'mysql -p123.com -e "show databases;\n"'
192.168.7.72 | CHANGED | rc=0 >>
Database
information_schema
db1
db2
db3
mysql
performance_schema
sys
PAGER set to stdoutmysql: [Warning] Using a password on the command line interface can be insecure.