MySQL Scale Out

简介

MySQL复制中较常见的复制架构有“一主一从”、“一主多从”、“双主”、“多级复制”和“多主环形机构”等,见下图;

wKioL1NpEgORcF2XAATJgegMOXY343.jpg

最常用,也最灵活的就要数“一主多从”复制架构了,其能满足多种需求,如:

  • 为不同的角色使用不同的备库(例如添加不同的索引或使用不同的存储引擎);

  • 把一台备库当做待用的主库,除了复制没有其它数据传输;

  • 将一台备库放在远程数据中心,用作灾难恢复;

  • 延迟一个或多个备库,以备灾难恢复;

  • 使用其中一个备库,作为备份、培训、开发或者测试使用服务器;

而“双主”复制架构则用于特殊的场景下,如两个处于不同地理位置的办公室,且都需要一份可写的数据拷贝;

这种架构最大的问题是如何解决数据冲突和不一致,尤其当两台服务器同时修改同一行记录,或同时在两台服务器上向一个包含auto_increment列的表里插入数据时;

而通过将一台服务器设置为只读的被动服务器,则可以很好的避免数据写入冲突的问题,这种主动-被动模式下的主-主复制架构使得反复切换主动和被动服务器非常方便,可以实现在不关闭服务器的情况下执行维护、优化表、升级操作系统或其他任务;

配置主动-被动模式的主-主复制架构的一般流程:

  • 确保两台服务器上有相同的数据;

  • 启用二进制日志,选择唯一的服务器ID,并创建复制账号;

  • 启用备库更新的日志记录,这是故障转移和故障恢复的关键;

  • 把被动服务器配置成只读,防止可能与主动服务器上的更新产生冲突;

  • 启动每个服务器的MySQL实例;

  • 将每个主库设置为对方的备库,使用新创建的二进制日志开始工作;

同时为了消除不同地理位置的站点单点故障问题,可以为每个主库增加冗余,即为每一个主库增加一个从库;

而MMM(=Master-Master Replication Manager for MySQL)则是一套脚本集合,用以监控、管理双主复制架构,通过设置一个可写的VIP和多个只读的VIP,完成故障自动转移、读负载分摊等功能;

 

架构设计

wKioL1NpEpCy3ACaAANLNO70Ry8648.jpg

服务器规划

wKiom1NpEumSkjTxAANRsHszrDg860.jpg

虚IP规划

wKioL1NpEtqCa90KAAKmQ02Oj3k481.jpg

 

配置部署

双主复制架构部署

MySQL或MariaDB的安装初始化可详见博客“MySQL架构

利用mysqld_multi在一台主机上启动多个mysqld实例

数据库初始化

# 在主机Host1和Host2上
cd /usr/local/mysql
scripts/mysql_install_db --user=mysql --datadir=/data/mariadb_data_3406/
scripts/mysql_install_db --user=mysql --datadir=/data/mariadb_data_3506/

 

数据库配置

 

# 在主机Host1上
vi /etc/my.cnf
[mysqld_multi]
mysqld = /usr/local/mysql/bin/mysqld_safe
mysqladmin = /usr/local/mysql/bin/mysqladmin
[mysqld1]
port = 3406
socket = /tmp/mysql3406.sock
skip-external-locking
key_buffer_size = 256M
max_allowed_packet = 1M
table_open_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
thread_concurrency = 2
datadir = /data/mariadb_data_3406
innodb_file_per_table = 1
default_storage_engine = InnoDB
log-bin=mysql-bin
relay-log=/data/relaylogs_3406/relay-bin # 指定中继日志路径
log_slave_updates=1 # 开启从库更新操作写入二进制日志功能
auto_increment_increment=2 # 双主复制中自增长字段的步长
auto_increment_offset=1 # 双主复制中自增长字段的起始值,此为1
sync_binlog = 1 # 可保证事务日志及时写入磁盘文件
binlog_format=row
server-id = 11  # 注意server-id的唯一性
[mysqld2]
port = 3506
socket = /tmp/mysql3506.sock
skip-external-locking
key_buffer_size = 256M
max_allowed_packet = 1M
table_open_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
thread_concurrency = 2
datadir = /data/mariadb_data_3506
innodb_file_per_table = 1
default_storage_engine = InnoDB
log-bin=mysql-bin
relay-log=/data/relaylogs_3506/relay-bin
log_slave_updates=1
sync_binlog = 1
binlog_format=row
server-id = 12
# 在主机Host2上
vi /etc/my.cnf
[mysqld_multi]
mysqld = /usr/local/mysql/bin/mysqld_safe
mysqladmin = /usr/local/mysql/bin/mysqladmin
[mysqld1]
port = 3406
socket = /tmp/mysql3406.sock
skip-external-locking
key_buffer_size = 256M
max_allowed_packet = 1M
table_open_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
thread_concurrency = 2
datadir = /data/mariadb_data_3406
innodb_file_per_table = 1
default_storage_engine = InnoDB
log-bin=mysql-bin
relay-log=/data/relaylogs_3406/relay-bin
log_slave_updates=1
auto_increment_increment=2 # # 双主复制中自增长字段的步长
auto_increment_offset=2 # 双主复制中自增长字段的起始值,此为2
sync_binlog = 1
binlog_format=row
server-id = 21
[mysqld2]
port = 3506
socket = /tmp/mysql3506.sock
skip-external-locking
key_buffer_size = 256M
max_allowed_packet = 1M
table_open_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
thread_concurrency = 2
datadir = /data/mariadb_data_3506
innodb_file_per_table = 1
default_storage_engine = InnoDB
log-bin=mysql-bin
relay-log=/data/relaylogs_3506/relay-bin
log_slave_updates=1
sync_binlog = 1
binlog_format=row
server-id = 22
####################################
主:
log-bin=mysql-bin
log-slave-updates=1
sync-binlog=1
binlog_format=row
relay-log= /data/relaylogs/relay-bin
server-id = 11
auto-increment-increment = 2
auto-increment-offset = 2

####################################
主:
log-bin=/data/binlogs/master-bin
binlog_format=row
sync_binlog = 1
log_slave_updates = 1
auto-increment-increment = 2
auto-increment-offset = 1
server-id = 21
relay-log = /data/relaylogs/relay-bin

######################################
从:
log-bin=mysql-bin
relay-log = /data/relaylogs/relay-bin
binlog_format=row
sync-binlog = 1
log-slave-updates = 1
datadir=/mydata/data
server-id = 12

#####################################
从:
relay-log=/data/relaylogs/relay-bin
log-bin=mysql-bin
binlog_format=row
log_slave_updates=1
sync-binlog =1
server-id = 22

 

启动数据库实例

# 在主机Host1和Host2上
/etc/init.d/mysqld_multi start 1 # 停止服务操作是/etc/init.d/mysqld_multi stop 1
/etc/init.d/mysqld_multi start 2 # 停止服务操作是/etc/init.d/mysqld_multi stop 2

登录数据库

# 在主机Host1和Host2上
mysql -S /tmp/mysql3406.sock # 登录master1或master2
mysql -S /tmp/mysql3506.sock # 登录slave1或slave2

 

创建所需账户(在Master1实例上)

grant replication client on *.* to '3m_moni'@'192.168.0.%' identified by '3m_12345'; # 创建MMM的监控账户
grant super,replication client,process on *.* to '3m_agen'@'192.168.0.%' identified by '3m_12345'; # 创建MMM的代理账户
grant replication slave on *.* to '3m_repl'@'192.168.0.%' identified by '3m_12345'; # 创建复制账户

 

配置数据同步

# 每次从库连接主库前,需先查询对应主库的二进制日志文件及其事件位置,即在主库上执行show master status即可,据此决定从库连接时的master_log_file和master_log_pos参数;
# slave1实例上
change master to master_host='192.168.0.45',master_port=3406,master_user='3m_repl',master_password='3m_12345',master_log_file='mysql-bin.000001',master_log_pos=2448;
# master2实例上
change master to master_host='192.168.0.45',master_port=3406,master_user='3m_repl',master_password='3m_12345',master_log_file='mysql-bin.000002',master_log_pos=365;
# slave2实例上
change master to master_host='192.168.0.46',master_port=3406,master_user='3m_repl',master_password='3m_12345',master_log_file='mysql-bin.000004',master_log_pos=342;
# master1实例上
change master to master_host='192.168.0.46',master_port=3406,master_user='3m_repl',master_password='3m_12345',master_log_file='mysql-bin.000004',master_log_pos=342;

查看同步状态

# 重点检查Slave_IO_Running、Slave_SQL_Running和Master_Server_Id等参数
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.0.45
                  Master_User: 3m_repl
                  Master_Port: 3406
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 326
               Relay_Log_File: relay-bin.000010
                Relay_Log_Pos: 613
        Relay_Master_Log_File: mysql-bin.000005
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
             Master_Server_Id: 11

 

MMM安装部署

Host1主机上:部署agent和monitor

 

yum -y install mysql-mmm-*
# 配置公共设置
vi /etc/mysql-mmm/mmm_common.conf
active_master_role      writer
<host default>
    cluster_interface       eth0
    pid_path                /var/run/mysql-mmm/mmm_agentd.pid
    bin_path                /usr/libexec/mysql-mmm/
    replication_user        3m_repl# 复制账户
    replication_password    3m_12345# 复制账户密码
    agent_user              3m_agen# agent账户
    agent_password          3m_12345# agent账户密码
</host>
<host db1>
    ip      192.168.0.45
    mysql_port 3406# 可指定需连接的mysqld的端口
    mode    master
    peer    db2# peer表示db1、db2是同等级别的
</host>
<host db2>
    ip      192.168.0.46
    mysql_port 3406
    mode    master
    peer    db1
</host>
<host db3>
    ip      192.168.0.45
    mysql_port 3506
    mode    slave
</host>
<host db4>
    ip      192.168.0.46
    mysql_port 3506
    mode    slave
</host>
<role writer>
    hosts   db1, db2
    ips     192.168.0.11# 可写VIP只配置一个
    mode    exclusive# 表示排它
</role>
<role reader>
    hosts   db1, db2,db3,db4
    ips     192.168.0.12,192.168.0.13,192.168.0.14,192.168.0.15 # 只读VIP可配置多个
    mode    balanced# 表示可以共用
</role>
==========
scp mmm_common.conf 192.168.0.46:/etc/mysql-mmm/ # 将公共配置文件拷贝至其它主机
==========
# 配置监控设置
vi /etc/mysql-mmm/mmm_mon.conf
include mmm_common.conf
<monitor>
    ip                  127.0.0.1
    pid_path            /var/run/mysql-mmm/mmm_mond.pid
    bin_path            /usr/libexec/mysql-mmm
    status_path         /var/lib/mysql-mmm/mmm_mond.status
    ping_ips            192.168.0.45,192.168.0.46# 健康监测时需ping的主机IP,不是VIP哦
    auto_set_online     60
</monitor>
<host default>
    monitor_user        3m_moni# 监控账户
    monitor_password    3m_12345 # 监控账户密码
</host>
debug 0
# 配置agent设置
vi /etc/mysql-mmm/mmm_agent.conf
include mmm_common.conf
this db1# 因为在一台主机上启用了2个mysqld实例,故可配置2个this参数哦
this db3

 

Host2主机上:只需部署agent

yum -y install mysql-mmm-agent
# 配置agent设置
vi /etc/mysql-mmm/mmm_agent.conf
include mmm_common.conf
this db2
this db4

服务启动

# 在主机Host1上
service mysql-mmm-agent  [root@mysql mysql
-mmm]# mmm_control show db1(192.168.0.45) master/ONLINE. Roles: reader(192.168.0.14), writer(192.168.0.11) db2(192.168.0.46) master/ONLINE. Roles: reader(192.168.0.13) db3(192.168.0.45) slave/ONLINE. Roles: reader(192.168.0.15) db4(192.168.0.46) slave/ONLINE. Roles: reader(192.168.0.12)

测试验证

查看双主复制架构中基于MMM实现的状态信息

 service mysql-mmm-monitor  start
# 在主机Host1上 [root@mysql mysql
-mmm]# mmm_control show db1(192.168.0.45) master/ONLINE. Roles: reader(192.168.0.14), writer(192.168.0.11) db2(192.168.0.46) master/ONLINE. Roles: reader(192.168.0.13) db3(192.168.0.45) slave/ONLINE. Roles: reader(192.168.0.15) db4(192.168.0.46) slave/ONLINE. Roles: reader(192.168.0.12)

手动进行各节点的健康监测

# 在主机Host1上
[root@mysql mysql-mmm]# mmm_control checks
db4  ping         [last change: 2014/05/06 22:38:27]  OK
db4  mysql        [last change: 2014/05/06 22:38:27]  OK
db4  rep_threads  [last change: 2014/05/06 22:38:27]  OK
db4  rep_backlog  [last change: 2014/05/06 22:38:27]  OK: Backlog is null
db2  ping         [last change: 2014/05/06 22:38:27]  OK
db2  mysql        [last change: 2014/05/06 22:38:27]  OK
db2  rep_threads  [last change: 2014/05/06 22:38:27]  OK
db2  rep_backlog  [last change: 2014/05/06 22:38:27]  OK: Backlog is null
db3  ping         [last change: 2014/05/06 22:38:27]  OK
db3  mysql        [last change: 2014/05/06 22:38:27]  OK
db3  rep_threads  [last change: 2014/05/06 22:38:27]  OK
db3  rep_backlog  [last change: 2014/05/06 22:38:27]  OK: Backlog is null
db1  ping         [last change: 2014/05/06 22:38:27]  OK
db1  mysql        [last change: 2014/05/06 22:38:27]  OK
db1  rep_threads  [last change: 2014/05/06 22:38:27]  OK
db1  rep_backlog  [last change: 2014/05/06 22:38:27]  OK: Backlog is null 

补充说明

  • 在本篇的演示案例中,前端程序若要与MySQL通信,则写库需连接192.168.0.11:3406,读库可连接192.168.0.12-15中的一个或多个,端口可能是3406或3506;

  • 在只读VIP漂移时,会导致前端程序连接的mysqld端口发生变化,所以生产环境下还是统一使用3306端口为宜;

  • 利用MMM实现了双主复制架构中的故障自动转移后,mysql并非直接与前端程序通信,还需配合使用读写分离器(如Ameoba),以统一对外的连接地址,由读写分离器负责读写的向下分配;

 

posted @ 2014-05-07 09:26 想想宝宝 阅读(...) 评论(...) 编辑 收藏
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