一、部署集群基础环境
目标：
本案例要求为MySQL集群准备基础环境，完成以下任务操作：
- 数据库授权
- 部署MySQL双主多从结构
- 配置本机hosts解析记录
方案：
使用4台RHEL 6虚拟机，如下图所示。其中192.168.4.10、192.168.4.11作为MySQL双主服务器，192.168.4.12、192.168.4.13作为主服务器的从服务器。
步骤：
步骤一：准备环境
[root@master1 ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.4.10 master1 master1.tarena.com
192.168.4.11 master2 master2.tarena.com
192.168.4.12 slave1 slave1.tarena.com
192.168.4.13 slave2 slave2.tarena.com
192.168.4.100 master1 master1.tarena.com
[root@master1 ~]# ping -c 2 master1
PING master1 (192.168.4.10) 56(84) bytes of data.
64 bytes from master1 (192.168.4.10): icmp_seq=1 ttl=64 time=0.378 ms
64 bytes from master1 (192.168.4.10): icmp_seq=2 ttl=64 time=0.396 ms
--- master1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.378/0.387/0.396/0.009 ms
[root@master1 ~]#
步骤二：部署数据库主机
1）安装启动数据库（4台数据库主机master1，master2，slave1，slave2执行以下操作）
[root@master1 ~]# tar xvf MySQL-5.6.15-1.el6.x86_64.rpm-bundle.tar //解压软件包
.. ..
[root@master1 ~]# rpm -Uvh MySQL-*.rpm //安装MySQL
.. ..
[root@master1 ~]# service mysql start
Starting MySQL. [确定]
2）初始化配置数据库（4台数据库主机master1，master2，slave1，slave2执行以下操作）
[root@master1 ~]# cat /root/.mysql_secret //查看随机生成密码
# The random password set for the root user at Thu May 7 22:15:47 2015 (local time): wW1BNAjD
[root@master1 ~]# mysql -uroot -pwW1BNAjD //使用随机生成密码登陆
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 1
Server version: 5.6.15
Copyright (c) 2000, 2013, 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> set password=password("pwd123"); //修改数据库root密码
Query OK, 0 rows affected (0.49 sec)
mysql> exit
Bye
[root@master1 ~]#
步骤三：部署双主多从结构
1）数据库授权（4台数据库主机master1，master2，slave1，slave2执行以下操作）
部署主从同步只需要授权一个主从同步用户即可，但是我们要部署MySQL-MMM架构，所以在这里我们将MySQL-MMM所需用户一并进行授权设置。再授权一个测试用户，在架构搭建完成时测试使用。
[root@master1 ~]# mysql -uroot -ppwd123
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 2
Server version: 5.6.15 MySQL Community Server (GPL)
Copyright (c) 2000, 2013, 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.
数据库授权部分为了方便试验我们直接允许所有地址访问了，真实环境需谨慎
mysql> grant replication slave on *.* to slaveuser@"%" identified by "pwd123"; //主从同步授权
Query OK, 0 rows affected (0.00 sec)
mysql> grant replication client on *.* to monitor@"%" identified by "monitor"; //MMM所需架构用户授权
Query OK, 0 rows affected (0.06 sec)
mysql> grant replication client,process,super on *.* to agent@"%" identified by "agent"; //MMM所需架构用户授权
Query OK, 0 rows affected (0.00 sec)
mysql> grant all on *.* to root@"%" identified by "pwd123"; //测试用户授权
Query OK, 0 rows affected (0.00 sec)
mysql>
2）开启主数据库binlog日志、设置server_id（master1，master2）
master1设置：
[root@master1 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
server_id=10 //设置server_id,该值集群中不可以重复
log-bin //开启bin-log日志
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[root@master1 ~]# service mysql restart //重启MySQL服务
Shutting down MySQL.. [确定]
Starting MySQL.. [确定]
[root@master1 ~]# ls /var/lib/mysql/master1-bin* //查看binlog日志是否生成
/var/lib/mysql/master1-bin.000001 /var/lib/mysql/master1-bin.index
[root@master1 ~]#
master2设置：
[root@master2 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
server_id=11
log-bin
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[root@master2 ~]# service mysql restart
Shutting down MySQL.. [确定]
Starting MySQL. [确定]
[root@master2 ~]# ls /var/lib/mysql/master2-bin.*
/var/lib/mysql/master2-bin.000001 /var/lib/mysql/master2-bin.index
3）从库设置server_id
slave1设置：
[root@slave1 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
server_id=12
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[root@slave1 ~]# service mysql restart
Shutting down MySQL.. [确定]
Starting MySQL.. [确定]
[root@slave1 ~]#
slave2设置：
[root@slave2 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
server_id=13
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[root@slave2 ~]# service mysql restart
Shutting down MySQL.. [确定]
Starting MySQL. [确定]
[root@slave2 ~]#
4）配置主从从从关系
配置master2、slave1、slave2成为master1的从服务器
查看master1服务器binlong日志使用节点信息：
[root@master1 ~]# mysql -uroot -ppwd123
.. ..
mysql> show master status\G
*************************** 1. row ***************************
File: master1-bin.000001
Position: 120
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
mysql>
设置master2为master1从：
[root@master2 ~]# mysql -uroot -ppwd123
.. ..
mysql> change master to //设置主服务器信息
-> master_host="192.168.4.10", //设置主服务器IP地址
-> master_user="slaveuser", //设置主从同步用户
-> master_password="pwd123", //设置主从同步密码
-> master_log_file="master1-bin.000001", //设置主库binlog日志名称
-> master_log_pos=120; //设置主从binlog日志使用节点
Query OK, 0 rows affected, 2 warnings (0.06 sec)
mysql> start slave; //启动同步进程
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G //查看主从是否成功
.. ..
启动同步进程后查看IO节点和SQL节点是否为Yes如果均为Yes表示主从正常。
Slave_IO_Running: Yes //IO节点正常
Slave_SQL_Running: Yes //SQL节点正常
.. ..
mysql>
设置slave1为master1从：
[root@slave1 ~]# mysql -uroot -ppwd123
.. ..
mysql> change master to
-> master_host="192.168.4.10",
-> master_user="slaveuser",
-> master_password="pwd123",
-> master_log_file="master1-bin.000001",
-> master_log_pos=120;
Query OK, 0 rows affected, 2 warnings (0.12 sec)
mysql> start slave;
Query OK, 0 rows affected (0.16 sec)
mysql> show slave status\G
.. ..
Slave_IO_Running: Yes //IO节点正常
Slave_SQL_Running: Yes //SQL节点正常
.. ..
mysql>
设置slave2为master1从：
[root@slave2 ~]# mysql -uroot -ppwd123
.. ..
mysql> change master to
-> master_host="192.168.4.10",
-> master_user="slaveuser",
-> master_password="pwd123",
-> master_log_file="master1-bin.000001",
-> master_log_pos=120;
Query OK, 0 rows affected, 2 warnings (0.13 sec)
mysql> start slave;
Query OK, 0 rows affected (0.27 sec)
mysql> show slave status\G
.. ..
Slave_IO_Running: Yes //IO节点正常
Slave_SQL_Running: Yes //SQL节点正常
.. ..
mysql>
5）配置主主从从关系，将master1配置为master2的从
查看master2的binlog使用信息：
[root@master2 ~]# mysql -uroot -ppwd123
.. ..
mysql> show master status\G
*************************** 1. row ***************************
File: master2-bin.000001
Position: 120
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
mysql>
设置master1成为master2的从：
[root@master1 ~]# mysql -uroot -ppwd123
.. ..
mysql> change master to
-> master_host="192.168.4.11",
-> master_user="slaveuser",
-> master_password="pwd123",
-> master_log_file="master2-bin.000001",
-> master_log_pos=120;
Query OK, 0 rows affected, 2 warnings (0.31 sec)
mysql> start slave;
Query OK, 0 rows affected (0.27 sec)
mysql> show slave status\G
.. ..
Slave_IO_Running: Yes //IO节点正常
Slave_SQL_Running: Yes //SQL节点正常
.. ..
mysql>
6）测试主从架构是否成功
master1更新数据，查看其它主机是否同步：
[root@master1 ~]# mysql -uroot -ppwd123
.. ..
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
mysql> create database tarena;
Query OK, 1 row affected (0.06 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
5 rows in set (0.00 sec)
mysql>
master2主机查看：
[root@master2 ~]# mysql -uroot -ppwd123 -e "show databases"
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@master2 ~]#
slave1主机查看：
[root@slave1 ~]# mysql -uroot -ppwd123 -e "show databases"
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@slave1 ~]#
slave2主机查看：
[root@slave2 ~]# mysql -uroot -ppwd123 -e "show databases"
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@slave2 ~]#
二、MySQL-MMM架构部署
目标：
本案例要求熟悉实现MySQL-MMM的架构部署，主要包括以下任务：
- 安装依赖包
- 安装软件包
- 配置MySQL-MMM
方案：
使用5台RHEL 6虚拟机，如下图所示。其中192.168.4.10、192.168.4.11作为MySQL双主服务器，192.168.4.12、 192.168.4.13作为主服务器的从服务器，192.168.4.100作为MySQL-MMM架构中管理监控服务器，实现监控MySQL主从服务 器的工作状态及决定故障节点的移除或恢复工作，架构搭建完成后使用客户机192.168.4.120进行访问，客户机需要安装MySQL-client软 件包。
步骤：
步骤一：安装MySQL-MMM
1）安装依赖关系（MySQL集群内5台服务器master1，master2，slave1，slave2，monitor）均需安装
[root@master1 ~]# yum -y install gcc* perl-Date-Manip perl-Date-Manip perl-Date-Manip perl-XML-DOM-XPath perl-XML-Parser perl-XML-RegExp rrdtool perl-Class-Singleton perl perl-DBD-MySQL perl-Params-Validate perl-MailTools perl-Time-HiRes
.. ..
2）安装MySQL-MMM软件依赖包（MySQL集群内5台服务器master1，master2，slave1，slave2，monitor）均需安装，软件包讲师提供
安装安装Log-Log4perl 类
[root@mysql-master1 ~]# rpm -ivh perl-Log-Log4perl-1.26-1.el6.rf.noarch.rpm
warning: perl-Log-Log4perl-1.26-1.el6.rf.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 6b8d79e6: NOKEY
Preparing... ######################### [100%]
1:perl-Log-Log4perl ######################## [100%]
安装Algorithm-Diff类
[root@mysql-master1 ~]# tar -zxvf Algorithm-Diff-1.1902.tar.gz //解压安装包
.. ..
[root@mysql-master1 ~]# cd Algorithm-Diff-1.1902 //切换到安装目录
[root@mysql-master1 Algorithm-Diff-1.1902]# perl Makefile.PL //生成makefile文件
Checking if your kit is complete...
Looks good
Writing Makefile for Algorithm::Diff
[root@mysql-master1 Algorithm-Diff-1.1902]# make && make install //编译，编译安装
.. ..
[root@mysql-master1 Algorithm-Diff-1.1902]# cd //切换到软件包目录
[root@mysql-master1 ~]#
安装Proc-Daemon类
[root@mysql-master1 ~]# tar -zxvf Proc-Daemon-0.03.tar.gz //解压安装包
.. ..
[root@mysql-master1 ~]# cd Proc-Daemon-0.03 //切换到安装目录
[root@mysql-master1 Proc-Daemon-0.03]# perl Makefile.PL //生成makefile文件
Checking if your kit is complete...
Looks good
Writing Makefile for Proc::Daemon
[root@mysql-master1 Proc-Daemon-0.03]# make && make install //编译，编译安装
.. ..
[root@mysql-master1 Proc-Daemon-0.03]# cd //切换到软件包目录
[root@mysql-master1 ~]#
安装Net-ARP虚拟IP分配工具：
[root@mysql-master1 ~]# gunzip Net-ARP-1.0.8.tgz //使用gunzip解压tgz格式的安装包
[root@mysql-master1 ~]# tar xvf Net-ARP-1.0.8.tar //解压tar安装包
.. ..
[root@mysql-master1 ~]# cd Net-ARP-1.0.8 //切换到安装目录
[root@mysql-master1 Net-ARP-1.0.8]# perl Makefile.PL //生成makefile文件
Module Net::Pcap is required for make test!
Checking if your kit is complete...
Looks good
Writing Makefile for Net::ARP
[root@mysql-master1 Net-ARP-1.0.8]# make && make install //编译，编译安装
.. ..
[root@mysql-master1 Net-ARP-1.0.8]# cd //切换到软件包目录
[root@mysql-master1 ~]#
安装Mysql-MMM软件包：
[root@mysql-master1 ~]# tar xvf mysql-mmm-2.2.1.tar.gz //解压安装包
.. ..
[root@mysql-master1 ~]# cd mysql-mmm-2.2.1 //切换到安装目录
[root@mysql-master1 mysql-mmm-2.2.1]# make && make install //编译，编译安装
.. ..
[root@mysql-master1 mysql-mmm-2.2.1]#
步骤二：修改配置文件
1）修改公共配置文件
本案例中MySQL集群的5台服务器（master1、master2、slave1、slave2、monitor）都需要配置，可以先配好一台后使用scp复制。
[root@master1 ~]# vim /etc/mysql-mmm/mmm_common.conf
active_master_role writer
<host default>
cluster_interface eth0 //设置主从同步的用户
pid_path /var/run/mmm_agentd.pid
bin_path /usr/lib/mysql-mmm/
replication_user slaveuser //设置主从同步的用户
replication_password pwd123 //设置主从同步用户密码
agent_user agent //mmm-agent控制数据库用户
agent_password agent //mmm-agent控制数据库用户密码
</host>
<host master1> //设置第一个主服务器
ip 192.168.4.10 //master1 IP 地址
mode master
peer master2 //指定另外一台主服务器
</host>
<host master2> //指定另外一台主服务器
ip 192.168.4.11
mode master
peer master1
</host>
<host slave1> //设置第一台从服务器
ip 192.168.4.12 //slave1 IP 地址
mode slave //本段落配置的是slave服务器
</host>
<host slave2>
ip 192.168.4.13
mode slave
</host>
<role writer> //设置写入服务器工作模式
hosts master1,master2 //提供写的主服务器
ips 192.168.4.200 //设置VIP地址
mode exclusive //排他模式
</role>
<role reader> //设置读取服务器工作模式
hosts slave1,slave2 //提供读的服务器信息
ips 192.168.4.201,192.168.4.202 //多个虚拟IP
mode balanced //均衡模式
</role>
[root@master1 ~]#
2）修改管理主机配置文件（monitor主机配置）
[root@monitor ~]# vim /etc/mysql-mmm/mmm_mon.conf
include mmm_common.conf
<monitor>
ip 192.168.4.100 //设置管理主机IP地址
pid_path /var/run/mmm_mond.pid
bin_path /usr/lib/mysql-mmm/
status_path /var/lib/misc/mmm_mond.status
ping_ips 192.168.4.10,192.168.4.11,192.168.4.12,192.168.4.13
//设置被监控数据库
</monitor>
<host default>
monitor_user monitor //监控数据库MySQL用户 monitor_password monitor //监控数据库MySQL用户密码
</host>
debug 0
[root@monitor ~]#
3）修改客户端配置文件
master1配置
[root@master1 ~]# cat /etc/mysql-mmm/mmm_agent.conf
include mmm_common.conf
this master1
master2配置
[root@master2 ~]# cat /etc/mysql-mmm/mmm_agent.conf
include mmm_common.conf
this master2
slave1配置
[root@slave1 ~]# cat /etc/mysql-mmm/mmm_agent.conf
include mmm_common.conf
this slave1
slave2配置
[root@slave2 ~]# cat /etc/mysql-mmm/mmm_agent.conf
include mmm_common.conf
this slave2
三、MySQL-MMM架构使用
目标：
本案例要求基于普通版的MySQL服务器改造MMM架构，完成以下任务操作：
- 启动MMM集群架构
- 设置集群中服务器为online状态
方案：
MySQL-MMM架构部署完成后需要启动，数据库端启动mmm-agent进程，管理端启动mmm-monitor进程，启动完成后设置所有数据库主机状态为online。
步骤：
步骤一：启动MMM集群架构
1）启动mmm-agent进程
master1操作：
[root@master1 ~]# /etc/init.d/mysql-mmm-agent start
Daemon bin: ‘/usr/sbin/mmm_agentd‘
Daemon pid: ‘/var/run/mmm_agentd.pid‘
Starting MMM Agent daemon... Ok
master2操作：
[root@master2 ~]# /etc/init.d/mysql-mmm-agent start
Daemon bin: ‘/usr/sbin/mmm_agentd‘
Daemon pid: ‘/var/run/mmm_agentd.pid‘
Starting MMM Agent daemon... Ok
slave1操作：
[root@master2 ~]# /etc/init.d/mysql-mmm-agent start
Daemon bin: ‘/usr/sbin/mmm_agentd‘
Daemon pid: ‘/var/run/mmm_agentd.pid‘
Starting MMM Agent daemon... Ok
slave2操作：
[root@slave2 ~]# /etc/init.d/mysql-mmm-agent start
Daemon bin: ‘/usr/sbin/mmm_agentd‘
Daemon pid: ‘/var/run/mmm_agentd.pid‘
Starting MMM Agent daemon... Ok
2）启动mmm-monitor进程
monitor主机操作：
[root@monitor ~]# /etc/init.d/mysql-mmm-monitor start
Daemon bin: ‘/usr/sbin/mmm_mond‘
Daemon pid: ‘/var/run/mmm_mond.pid‘
Starting MMM Monitor daemon: Ok
步骤二：设置集群中服务器为online状态
控制命令只能在管理端monitor服务器上执行。
查看当前集群中各服务器状态：
[root@monitor ~]# mmm_control show
master1(192.168.4.10) master/AWAITING_RECOVERY. Roles:
master2(192.168.4.11) master/AWAITING_RECOVERY. Roles:
slave1(192.168.4.12) slave/AWAITING_RECOVERY. Roles:
slave2(192.168.4.13) slave/AWAITING_RECOVERY. Roles:
设置4台数据库主机状态为online：
[root@monitor ~]# mmm_control set_online master1
OK: State of ‘master1‘ changed to ONLINE. Now you can wait some time and check its new roles!
[root@monitor ~]# mmm_control set_online master2
OK: State of ‘master2‘ changed to ONLINE. Now you can wait some time and check its new roles!
[root@monitor ~]# mmm_control set_online slave1
OK: State of ‘slave1‘ changed to ONLINE. Now you can wait some time and check its new roles!
[root@monitor ~]# mmm_control set_online slave2
OK: State of ‘slave2‘ changed to ONLINE. Now you can wait some time and check its new roles!
[root@monitor ~]#
再次查看当前集群中各服务器状态：
[root@monitor ~]# mmm_control show
master1(192.168.4.10) master/ONLINE. Roles: writer(192.168.4.200)
master2(192.168.4.11) master/ONLINE. Roles:
slave1(192.168.4.12) slave/ONLINE. Roles: reader(192.168.4.201)
slave2(192.168.4.13) slave/ONLINE. Roles: reader(192.168.4.202)
[root@monitor ~]#
步骤三：测试MySQL-MMM架构
1）客户机安装MySQL-client软件包
[root@client ~]# tar xvf MySQL-5.6.15-1.el6.x86_64.rpm-bundle.tar
.. ..
[root@client ~]# rpm -ivh MySQL-client-5.6.15-1.el6.x86_64.rpm
.. ..
2）MySQL-MMM虚拟IP访问测试
[root@client ~]# mysql -h192.168.4.200 -uroot -ppwd123 -e "show databases"
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@client ~]#
[root@client ~]# mysql -h192.168.4.200 -uroot -ppwd123 -e "show databases"
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@client ~]#
[root@client ~]# mysql -h192.168.4.202 -uroot -ppwd123 -e "show databases"
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@client ~]#
3）主数据库宕机测试
[root@master1 ~]# service mysql stop //停止master1上服务
Shutting down MySQL.... [确定]
[root@master1 ~]#
[root@monitor ~]# mmm_control show //查看集群内服务器状态
通过输出信息可以看到虚拟IP从master1切换到master2：
master1(192.168.4.10) master/HARD_OFFLINE. Roles:
master2(192.168.4.11) master/ONLINE. Roles: writer(192.168.4.200)
slave1(192.168.4.12) slave/ONLINE. Roles: reader(192.168.4.201)
slave2(192.168.4.13) slave/ONLINE. Roles: reader(192.168.4.202)
[root@monitor ~]#
[root@client ~]# mysql -h192.168.4.200 -uroot -ppwd123 -e "show databases" //访问虚拟IP测试
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| tarena |
| test |
+--------------------+
[root@client ~]#
