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)
二、配置运行环境
[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
[root@node142 ~]# vim /etc/selinux/config
SELINUX=disabled
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
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
5、配置时间同步服务
[root@node248 ~]# crontab -e
*/10 * * * * ntpdate ntp3.aliyun.com
6、分别重启3节点
[root@node142 ~]# reboot
[root@node146 ~]# reboot
[root@node147 ~]# reboot
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'"
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}
[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"
[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
[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
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';
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
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)
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
