Percona XtraDB Cluster(简称PXC)是很多企业基于MySQL实现集群方案的不二选择。PXC它支持服务高可用,数据同步复制(并发复制)，几乎无延迟；多个可同时读写节点，可实现写扩展等等。之前整理过一篇PXC 5.6的文章，本文是基于CentOS 7 PXC 5.7版一个更为标准的安装，可供大家参考。
一、当前OS环境：
[root@node142 ~]# more /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)
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二、配置运行环境
1、修改主机hosts文件
[root@node142 ~]# vim /etc/hosts
127.0.0.1 localhost.localdomain localhost
192.168.81.142 node142.example.com node142
192.168.81.146 node146.example.com node146
192.168.81.147 node147.example.com node147
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2、修改selinux配置文件
[root@node142 ~]# vim /etc/selinux/config
SELINUX=disabled
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3、分发配置文件到其余节点
[root@node142 ~]# scp /etc/hosts 192.168.81.146:/etc/hosts
[root@node142 ~]# scp /etc/hosts 192.168.81.147:/etc/hosts
[root@node142 ~]# scp /etc/selinux/config 192.168.81.146:/etc/hosts
[root@node142 ~]# scp /etc/selinux/config 192.168.81.147:/etc/hosts
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4、分别3节点配置防火墙，如下示例(仅列出一个节点)
[root@node142 ~]# firewall-cmd --add-port=3306/tcp --permanent
[root@node142 ~]# firewall-cmd --add-port=4567/tcp --permanent
[root@node142 ~]# firewall-cmd --add-port=4568/tcp --permanent
[root@node142 ~]# firewall-cmd --add-port=4444/tcp --permanent
[root@node142 ~]# firewall-cmd --reload
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5、配置时间同步服务
[root@node248 ~]# crontab -e
*/10 * * * * ntpdate ntp3.aliyun.com
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6、分别重启3节点
[root@node142 ~]# reboot
[root@node146 ~]# reboot
[root@node147 ~]# reboot
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三、安装Percona XtraDB Cluster 5.7
1、3节点分别安装Percona XtraDB Cluster 5.7 (如下示例)
[root@node142 ~]# rpm -Uvh https://www.percona.com/downloads/percona-release/redhat/latest/percona-release-0.1-4.noarch.rpm
[root@node142 ~]# yum install Percona-XtraDB-Cluster-57 -y
yum安装时会提示UDFs功能，根据需要可以在mysql启动后执行以下语句
Percona XtraDB Cluster is distributed with several useful UDFs from Percona Toolkit.
Run the following commands to create these functions:
mysql -e "CREATE FUNCTION fnv1a_64 RETURNS INTEGER SONAME 'libfnv1a_udf.so'"
mysql -e "CREATE FUNCTION fnv_64 RETURNS INTEGER SONAME 'libfnv_udf.so'"
mysql -e "CREATE FUNCTION murmur_hash RETURNS INTEGER SONAME 'libmurmur_udf.so'"
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四、配置mysql及集群配置文件
主要包括mysqld.cnf，mysqld_safe.cnf，wsrep.cnf
在当前的这个版本中，my.cnf为主配置文件，其余的配置文件放在/etc/percona-xtradb-cluster.conf.d目录
在这几个配置文件中，大家根据自己的需要定制，本演示仅作基本修改
1、备份配置文件
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/mysqld.cnf{,.org}
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/mysqld_safe.cnf{,.org}
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/wsrep.cnf{,.org}
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2、修改配置文件
[root@node142 ~]# vim /etc/percona-xtradb-cluster.conf.d/mysqld.cnf
[root@node142 ~]# more /etc/percona-xtradb-cluster.conf.d/mysqld.cnf
# Template my.cnf for PXC
# Edit to your requirements.
[client]
socket=/var/lib/mysql/mysql.sock
[mysqld]
server-id=142 #这个参数3个节点要使用不同的id
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
log-bin=/var/lib/mysqlbin
log_slave_updates
expire_logs_days=7
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
log_bin_trust_function_creators=on
character_set_server = utf8 ##Author : Leshami
collation_server = utf8_bin ##Blog : http://blog.csdn.net/leshami
[root@node142 ~]# vim /etc/percona-xtradb-cluster.conf.d/wsrep.cnf
[root@node142 ~]# grep -vE "^#|^$" /etc/percona-xtradb-cluster.conf.d/wsrep.cnf
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.81.142,192.168.81.146,192.168.81.147
binlog_format=ROW
default_storage_engine=InnoDB
wsrep_slave_threads= 8
wsrep_log_conflicts
innodb_autoinc_lock_mode=2
wsrep_node_address=192.168.81.142 ##这个参数要改成相应的IP
wsrep_cluster_name=pxc-cluster
wsrep_node_name=node142 ##这个参数要改成相应的节点名称
pxc_strict_mode=PERMISSIVE
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="sstuser:s3cretPass"
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3、修改剩余节点配置文件
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/mysqld.cnf{,.146}
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/mysqld.cnf{,.147}
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/wsrep.cnf{,.146}
[root@node142 ~]# cp /etc/percona-xtradb-cluster.conf.d/wsrep.cnf{,.147}
[root@node142 ~]# vim /etc/percona-xtradb-cluster.conf.d/mysqld.cnf.146 #修改对应的server_id
[root@node142 ~]# vim/etc/percona-xtradb-cluster.conf.d/mysqld.cnf.147 #修改对应的server_id
以下操作，分别修改wsrep_node_name，wsrep_node_address至相应的节点名称以及IP地址
[root@node142 ~]# vim /etc/percona-xtradb-cluster.conf.d/wsrep.cnf.146
[root@node142 ~]# vim /etc/percona-xtradb-cluster.conf.d/wsrep.cnf.147
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4、比较配置文件，并将配置文件分发到各个节点
[root@node142 ~]# cd /etc/percona-xtradb-cluster.conf.d/
[root@node142 percona-xtradb-cluster.conf.d]# diff mysqld.cnf mysqld.cnf.146
7c7
< server-id=142
---
> server-id=146
[root@node142 percona-xtradb-cluster.conf.d]# diff mysqld.cnf mysqld.cnf.147
7c7
< server-id=142
---
> server-id=147
[root@node142 percona-xtradb-cluster.conf.d]# diff wsrep.cnf wsrep.cnf.146
28c28
< wsrep_node_address=192.168.81.142
---
> wsrep_node_address=192.168.81.146
32c32
< wsrep_node_name=node142
---
> wsrep_node_name=node146
[root@node142 percona-xtradb-cluster.conf.d]# diff wsrep.cnf wsrep.cnf.147
28c28
< wsrep_node_address=192.168.81.142
---
> wsrep_node_address=192.168.81.147
32c32
< wsrep_node_name=node142
---
> wsrep_node_name=node147
[root@node142 percona-xtradb-cluster.conf.d]# scp mysqld.cnf.146 node146:/etc/percona-xtradb-cluster.conf.d/mysqld.cnf
[root@node142 percona-xtradb-cluster.conf.d]# scp wsrep.cnf.146 node146:/etc/percona-xtradb-cluster.conf.d/wsrep.cnf
[root@node142 percona-xtradb-cluster.conf.d]# scp mysqld.cnf.147 node147:/etc/percona-xtradb-cluster.conf.d/mysqld.cnf
[root@node142 percona-xtradb-cluster.conf.d]# scp wsrep.cnf.147 node147:/etc/percona-xtradb-cluster.conf.d/wsrep.cnf
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五、启动PXC集群
1、启动第一个节点
[root@node142 ~]# systemctl start mysql@bootstrap.service
[root@node142 ~]# grep "temporary password" /var/log/mysqld.log
2017-12-28T08:57:24.231185Z 1 [Note] A temporary password is generated for root@localhost: wj!v<z/2)ctZ
[root@node142 ~]# mysql -uroot -p
Enter password:
mysql> alter user 'root'@'localhost' identified by '123456';
mysql> create user 'sstuser'@'localhost' identified by 's3cretpass';
mysql> grant reload, lock tables, replication client, process on *.* to 'sstuser'@'localhost';
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2、启动剩余节点
[root@node146 ~]# systemctl start mysql
[root@node147 ~]# systemctl start mysql
注，如果你使用的是CentOS7.2.1511，会发现mysql可以正常启动，但是未加入集群的情况
需要升级openssl，建议全部升级后再启动集群，这问题在CentOS 7.4.1708不存在即openssl版本较新
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六、验证集群
在146上完成如下操作
[root@node146 ~]# mysql -uroot -p
mysql> show variables like 'version';
+---------------+--------------+
| Variable_name | Value |
+---------------+--------------+
| version | 5.7.19-17-57 |
+---------------+--------------+
1 row in set (0.00 sec)
mysql> create database pxcdb;
mysql> use pxcdb;
mysql> create table t1(id tinyint,ename varchar(20));
mysql> insert into t1 values(1,'Leshami');
在147上进行验证
[root@node147 ~]# mysql -uroot -p
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| pxcdb |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> show variables like 'server_id';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 147 |
+---------------+-------+
1 row in set (0.01 sec)
mysql> select * from pxcdb.t1;
+------+---------+
| id | ename |
+------+---------+
| 1 | Leshami |
+------+---------+
1 row in set (0.00 sec)
--查看集群状态
mysql> show status like '%wsrep_clust%';
+--------------------------+--------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------+
| wsrep_cluster_conf_id | 13 | ## Author : Leshami
| wsrep_cluster_size | 3 | ## Blog : http://blog.csdn.net/leshami
| wsrep_cluster_state_uuid | aeb87793-ebb2-11e7-b33e-eeaf4988bbe4 |
| wsrep_cluster_status | Primary | ## Weixin/QQ : 645746311
+--------------------------+--------------------------------------+
4 rows in set (0.00 sec)
mysql> show status like 'wsrep_connected';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| wsrep_connected | ON |
+-----------------+-------+
1 row in set (0.00 sec)
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七、openssl版本过低导致的错误
2017-12-28T09:23:19.605353Z 0 [ERROR] WSREP: wsrep_load(): dlopen(): /usr/lib64/galera3/libgalera_smm.so:
symbol SSL_COMP_free_compression_methods, version libssl.so.10 not defined in file libssl.so.10 with link time reference
2017-12-28T09:23:19.605379Z 0 [ERROR] WSREP: Failed to load wsrep_provider (/usr/lib64/galera3/libgalera_smm.so).
Error: Invalid argument (code: 22). Reverting to no provider.
2017-12-28T09:23:19.605386Z 0 [Note] WSREP: Setting wsrep_ready to false
[root@node146 ~]# rpm -qa|grep openssl
openssl-1.0.1e-42.el7.9.x86_64
openssl-libs-1.0.1e-42.el7.9.x86_64
[root@node146 ~]# yum update openssl -y
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