作者在2014Oracle数据库嘉年华中有幸听到了关于去哪网的MySQL数据库基于PXC的高可用架构设计主题。 MySQL和Oracle是完全不同的两种数据库，Oracle重于管理，而MySQL更重要的是架构设计。笔者对MySQL以及新技术也是充满了好奇，索性回来自己搭建一个测试环境

作者在2014Oracle数据库嘉年华中有幸听到了关于去哪网的MySQL数据库基于PXC的高可用架构设计主题。

MySQL和Oracle是完全不同的两种数据库，Oracle重于管理，而MySQL更重要的是架构设计。笔者对MySQL以及新技术也是充满了好奇，索性回来自己搭建一个测试环境。

操作系统：CentOS 6.6

软件版本：5.5.39-36.0-55 PerconaXtraDB Cluster (GPL)

节点信息：

安装过程

安装PXC，这里使用的是Percona以及EPEL的官方repositories ：

http://www.percona.com/doc/percona-server/5.5/installation/yum_repo.html?id=repositories:yum

http://fedoraproject.org/wiki/EPEL

yum installhttp://www.percona.com/downloads/percona-release/redhat/0.1-3/percona-release-0.1-3.noarch.rpmyum installhttp://mirrors.ustc.edu.cn/fedora/epel/6/i386/epel-release-6-8.noarch.rpmyum -y install Percona-XtraDB-Cluster-serverPercona-XtraDB-Cluster-client Percona-Server-shared-compat percona-xtrabackup

每台机器开启PXC，之后添加SST账户：

DELETE FROM mysql.user WHERE user='';GRANT RELOAD, LOCK TABLES, REPLICATION CLIENT ON *.* TO 'sstuser'@'localhost' IDENTIFIED BY 'sstuser';;FLUSH PRIVILEGES;

每个节点关闭PXC。编辑第一个节点的PXC设置。

[mysqld]server_id=1wsrep_provider=/usr/lib64/libgalera_smm.sowsrep_cluster_address="gcomm://192.168.0.200,192.168.0.201,192.168.0.202"wsrep_sst_auth=sstuser:sstuserwsrep_provider_options="gcache.size=4G"wsrep_cluster_name=Perconawsrep_sst_method=xtrabackupwsrep_node_name=pxc1wsrep_slave_threads=4log_slave_updatesinnodb_locks_unsafe_for_binlog=1innodb_autoinc_lock_mode=2

开启第一个节点（如果集群关闭，每次拥有正确信息的节点使用此命令开启集群）

[root@pxc1 ~]# service mysql bootstrap-pxcBootstrapping PXC (Percona XtraDBCluster)Starting MySQL (Percona XtraDB Cluster)..[  OK  ] 

编辑另外两个节点的my.cnf配置文件需要修改的内容：

server_id=2wsrep_node_name=pxc2

将其他两个节点加入到集群中

service mysql start

至此，集群安装结束。

遇到的问题

以下是配置过程中的报错信息以及解决方法：

现象：

开启PXC节点的时候遇到

Failed to read output of: 'ip addr show | grep -E '^[ ]*inet' | grep -m1global | awk '{ print $2 }' | sed -e 's/\/.*//''........141120 22:46:35 [ERROR] WSREP: Permission denied141120 22:46:35 [ERROR] WSREP: failed to open gcomm backend connection: 13:error while trying to listen 'tcp://0.0.0.0:4567?socket.non_blocking=1', asioerror 'Permission denied': 13 (Permission denied)

原因：

由于开启了SELINUX。

解决方法：

编辑文件/etc/sysconfig/selinux

把SELINUX设为disabled

重启后就会忽略selinux，或者直接执行命令

setenforce 0

立即生效。

现象：

添加节点到集群中的时候遇到

last inactive check morethan PT1.5S ago (PT3.50529S), skipping check

卡在这里

原因：

iptables

解决方法：

关闭iptables

chkconfig iptables off

service iptables stop

简单测试

[root@pxc1 ~]# mysqlWelcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 7Server version: 5.5.39-36.0-55 Percona XtraDB Cluster (GPL), Release rel36.0, Revision 824, WSREP version 25.11, wsrep_25.11.r4023Copyright (c) 2009-2014 Percona LLC and/or its affiliatesCopyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> show global status like 'wsrep_cluster_size';+--------------------+-------+| Variable_name      | Value |+--------------------+-------+| wsrep_cluster_size | 2     |+--------------------+-------+1 row in set (0.00 sec)mysql> show global status like 'wsrep_cluster_size';+--------------------+-------+| Variable_name      | Value |+--------------------+-------+| wsrep_cluster_size | 3     |+--------------------+-------+1 row in set (0.00 sec)mysql> create database dexdb ;Query OK, 1 row affected (0.01 sec)mysql> use dexdbDatabase changedmysql> create table dextb (id int ,name char(10))  engine=innodb ;Query OK, 0 rows affected (0.03 sec)mysql> insert into dextb values (1,'22') ;Query OK, 1 row affected (0.01 sec)mysql> insert into dextb values (1,'22') ;Query OK, 1 row affected (0.00 sec)mysql> commit ;Query OK, 0 rows affected (0.00 sec)mysql> select * from dextb ;+------+------+| id   | name |+------+------+|    1 | 22   ||    1 | 22   |+------+------+2 rows in set (0.00 sec)[root@pxc2 ~]# mysqlWelcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 6Server version: 5.5.39-36.0-55 Percona XtraDB Cluster (GPL), Release rel36.0, Revision 824, WSREP version 25.11, wsrep_25.11.r4023Copyright (c) 2009-2014 Percona LLC and/or its affiliatesCopyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> show database ;ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'database' at line 1mysql> show databases ;+--------------------+| Database           |+--------------------+| information_schema || dexdb              || mysql              || performance_schema || test               |+--------------------+5 rows in set (0.01 sec)mysql> use dexdbReading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> select * from dextb ;+------+------+| id   | name |+------+------+|    1 | 22   ||    1 | 22   |+------+------+2 rows in set (0.00 sec)[root@pxc3 ~]# service mysql startMySQL (Percona XtraDB Cluster) is not running, but lock file (/var/lock/subsys/mysql) exists[FAILED]Starting MySQL (Percona XtraDB Cluster).....[  OK  ][root@pxc3 ~]# mysqlWelcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 6Server version: 5.5.39-36.0-55 Percona XtraDB Cluster (GPL), Release rel36.0, Revision 824, WSREP version 25.11, wsrep_25.11.r4023Copyright (c) 2009-2014 Percona LLC and/or its affiliatesCopyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> use dexdbReading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabas<strong style="color:transparent">本文来源gao@daima#com搞(%代@#码@网&</strong>e changedmysql> select * from dextb ;+------+------+| id   | name |+------+------+|    1 | 22   ||    1 | 22   |+------+------+2 rows in set (0.00 sec)

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