MGR集群搭建及配置过程
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2022-06-03 23:06:21
mgr全称mysql group replication（mysql组复制），是mysql官方于2016年12月推出的一个全新的高可用与高扩展的解决方案。mgr提供了高可用、高扩展、高可靠的mysql...
mgr全称mysql group replication（mysql组复制），是mysql官方于2016年12月推出的一个全新的高可用与高扩展的解决方案。mgr提供了高可用、高扩展、高可靠的mysql集群服务。在mgr出现之前，用户常见的mysql高可用方式，无论怎么变化架构，本质就是master-slave架构。mysql 5.7版本开始支持无损半同步复制（lossless semi-sync replication），从而进一步提示数据复制的强一致性。
mgr是mysql数据库未来发展的一个重要方向。
注意：根据本人测试group_replication.so插件是mysql-community-server安装包中携带，如果是rpm安装或yum安装存放地址为/usr/lib64/mysql/plugin/目录下，看下图。另外在安装5.7.16版本时是没有这个插件，而在安装5.7.20版本有这个插件，推测这是一个5.7.16到5.7.20之间新加的插件，个人建议安装5.7.20以上的版本。另外大家请在安装好mysql后查看一下是否存在这个插件。
如果提示group_replication.so不存在，或提示有问题并且查看时发现group_replication.so不存在，请重点看一下mysql的版本。（我搜了一大圈，没有一个人说这个问题。表示怀疑自己，如果我错了，请留言。）
(1).mgr的特性
高一致性。基于原生复制及paxos协议的组复制技术，并以插件的方式提供，提供一致数据安全保证；
高容错性。只要不是大多数节点坏掉就可以继续工作，有自动检测机制，当不同节点产生资源争用冲突时，不会出现错误，按照先到者优先原则进行处理，并且内置了自动化脑裂防护机制；
高扩展性。节点的新增和移除都是自动的，新节点加入后，会自动从其他节点上同步状态，直到新节点和其他节点保持一致，如果某节点被移除了，其他节点自动更新组信息，自动维护新的组信息；
高灵活性。有单主模式和多主模式，单主模式下，会自动选主，所有更新操作都在主上进行；多主模式下，所有server都可以同时处理更新操作。
(2).搭建mgr的基础结构要求和使用限制（重点）
基础结构要求：1.引擎必须为innodb,因为需事务支持在commit时对各节点进行冲突检查；2.每个表必须有主键，在进行事务冲突检测时需要利用主键值对比；3.必须开启binlog且为row格式；4.开启gtid，且主从状态信息存于表中（--master-info-repository=table 、--relay-log-info-repository=table），--log-slave-updates打开；5.一致性检测设置--transaction-write-set-extraction=xxhash64。
使用限制：1.rp和普通复制binlog校验不能共存，需设置--binlog-checksum=none；2.不支持gap lock(间隙锁)，隔离级别需设置为read_committed；3.不支持对表进行锁操作（lock /unlock table）,不会发送到其他节点执行 ,影响需要对表进行加锁操作的情况，列入mysqldump全表备份恢复操作；4.不支持serializable(序列化)隔离级别；5.ddl语句不支持原子性，不能检测冲突，执行后需自行校验是否一；6.多主模式下不支持外键，单主模式下支持外键；最多9个节点，超过9台无法加入集群
(3).实验环境
youxi1 192.168.1.6 centos7.6 mysql5.7.26 端口号3306 server-id=1
youxi2 192.168.1.7 centos7.6 mysql5.7.26 端口号3306 server-id=2
youxi3 192.168.1.8 centos7.6 mysql5.7.26 端口号3306 server-id=3
另外，三台服务器上都进行ip的映射（如果此处不映射，请修改/etc/my.cnf配置文件中对应的域名为ip地址）
[root@youxi1 ~]# vim /etc/hosts 192.168.1.6 youxi1.cn youxi1 //长域名和短域名只要映射一个即可 192.168.1.7 youxi2.cn youxi2 192.168.1.8 youxi3.cn youxi3
(1).单主模式
我是在空数据库下操作，如果主数据集已存在数据，需要将主数据库的数据导出再导入到从数据库。另外还需保证引擎为innodb，每个表必须存在主键。
1）以youxi1作为主服务器，对youxi1进行配置
创建一个复制用的用户
mysql> grant replication slave on *.* to 'repl'@'192.168.1.%' identified by '12345678'; query ok, 0 rows affected, 1 warning (0.01 sec) mysql> flush privileges; query ok, 0 rows affected (0.00 sec)
修改配置文件，加入到[mysqld]模块下。然后重启mysqld
[root@youxi1 ~]# vim /etc/my.cnf server-id=1 //mysql服务id gtid-mode=on //全局事务 enforce-gtid-consistency=on //强制gtid的一致性 master-info-repository=table //将master.info元数据保存在系统表中 relay-log-info-repository=table //将relay.info元数据保存在系统表中 binlog-checksum=none //禁用二进制日志事件校验 log-slave-updates=on //级联复制 log-bin=binlog //开启二进制日志记录 binlog-format=row //以行的格式记录 transaction-write-set-extraction=xxhash64 //使用哈希算法将其编码为散列 loose-group_replication_group_name='ce9be252-2b71-11e6-b8f4-00212844f856' //加入的组名，可以修改，只要格式对 loose-group_replication_start_on_boot=off //不自动启用组复制集群 loose-group_replication_local_address='youxi1:33061' //以本机端口33061接受来自组中成员的传入连接 loose-group_replication_group_seeds='youxi1:33061,youxi2:33062,youxi3:33063' //组中成员访问表 loose-group_replication_bootstrap_group=off //不启用引导组 [root@youxi1 ~]# systemctl restart mysqld
注意：如果防火墙是打开的，记得添加mysql的端口号。
[root@youxi1 ~]# firewall-cmd --permanent --zone=public --add-port={3306,33061}/tcp
success
[root@youxi1 ~]# firewall-cmd --reload
success
[root@youxi1 ~]# firewall-cmd --zone=public --list-ports
3306/tcp 33061/tcp修改master信息，构建组复制（group replication）集群信息
mysql> change master to master_user='repl',master_password='12345678' for channel 'group_replication_recovery'; query ok, 0 rows affected, 2 warnings (0.04 sec)
安装组复制（group replication）插件，并查看组件信息
mysql> install plugin group_replication soname 'group_replication.so'; query ok, 0 rows affected (0.21 sec) mysql> show plugins; //查看组件是否安装成功 +----------------------------+----------+--------------------+----------------------+---------+ | name | status | type | library | license | +----------------------------+----------+--------------------+----------------------+---------+ | binlog | active | storage engine | null | gpl | | mysql_native_password | active | authentication | null | gpl | | sha256_password | active | authentication | null | gpl | | csv | active | storage engine | null | gpl | | memory | active | storage engine | null | gpl | | innodb | active | storage engine | null | gpl | | innodb_trx | active | information schema | null | gpl | | innodb_locks | active | information schema | null | gpl | | innodb_lock_waits | active | information schema | null | gpl | | innodb_cmp | active | information schema | null | gpl | | innodb_cmp_reset | active | information schema | null | gpl | | innodb_cmpmem | active | information schema | null | gpl | | innodb_cmpmem_reset | active | information schema | null | gpl | | innodb_cmp_per_index | active | information schema | null | gpl | | innodb_cmp_per_index_reset | active | information schema | null | gpl | | innodb_buffer_page | active | information schema | null | gpl | | innodb_buffer_page_lru | active | information schema | null | gpl | | innodb_buffer_pool_stats | active | information schema | null | gpl | | innodb_temp_table_info | active | information schema | null | gpl | | innodb_metrics | active | information schema | null | gpl | | innodb_ft_default_stopword | active | information schema | null | gpl | | innodb_ft_deleted | active | information schema | null | gpl | | innodb_ft_being_deleted | active | information schema | null | gpl | | innodb_ft_config | active | information schema | null | gpl | | innodb_ft_index_cache | active | information schema | null | gpl | | innodb_ft_index_table | active | information schema | null | gpl | | innodb_sys_tables | active | information schema | null | gpl | | innodb_sys_tablestats | active | information schema | null | gpl | | innodb_sys_indexes | active | information schema | null | gpl | | innodb_sys_columns | active | information schema | null | gpl | | innodb_sys_fields | active | information schema | null | gpl | | innodb_sys_foreign | active | information schema | null | gpl | | innodb_sys_foreign_cols | active | information schema | null | gpl | | innodb_sys_tablespaces | active | information schema | null | gpl | | innodb_sys_datafiles | active | information schema | null | gpl | | innodb_sys_virtual | active | information schema | null | gpl | | myisam | active | storage engine | null | gpl | | mrg_myisam | active | storage engine | null | gpl | | performance_schema | active | storage engine | null | gpl | | archive | active | storage engine | null | gpl | | blackhole | active | storage engine | null | gpl | | federated | disabled | storage engine | null | gpl | | partition | active | storage engine | null | gpl | | ngram | active | ftparser | null | gpl | | validate_password | disabled | validate password | validate_password.so | gpl | | group_replication | active | group replication | group_replication.so | gpl | +----------------------------+----------+--------------------+----------------------+---------+ 46 rows in set (0.00 sec)
作为主服务器需要由这台服务器开启引导，开启组复制（group replication）集群
mysql> set global group_replication_bootstrap_group=on; //开启组复制引导 query ok, 0 rows affected (0.00 sec) mysql> start group_replication; //开启组复制 query ok, 0 rows affected (2.24 sec) mysql> set global group_replication_bootstrap_group=off; //关闭组复制引导 query ok, 0 rows affected (0.00 sec)
查看到添加到组复制集群的服务器信息
mysql> select * from performance_schema.replication_group_members; +---------------------------+--------------------------------------+-------------+-------------+--------------+ | channel_name | member_id | member_host | member_port | member_state | +---------------------------+--------------------------------------+-------------+-------------+--------------+ | group_replication_applier | c9e3662b-9020-11e9-94aa-000c29721e89 | youxi1 | 3306 | online | +---------------------------+--------------------------------------+-------------+-------------+--------------+ 1 row in set (0.00 sec)
2）对youxi2进行配置
创建一个复制用的用户
mysql> grant replication slave on *.* to 'repl'@'192.168.1.%' identified by '12345678'; query ok, 0 rows affected, 1 warning (0.01 sec) mysql> flush privileges; query ok, 0 rows affected (0.01 sec)
修改配置文件，加入到[mysqld]模块下。然后重启mysqld
[root@youxi2 ~]# vim /etc/my.cnf server-id=2 //修改 gtid-mode=on enforce-gtid-consistency=on master-info-repository=table relay-log-info-repository=table binlog-checksum=none log-slave-updates=on log-bin=binlog binlog-format=row transaction-write-set-extraction=xxhash64 loose-group_replication_group_name='ce9be252-2b71-11e6-b8f4-00212844f856' loose-group_replication_start_on_boot=off loose-group_replication_local_address='youxi2:33062' //修改 loose-group_replication_group_seeds='youxi1:33061,youxi2:33062,youxi3:33063' loose-group_replication_bootstrap_group=off [root@youxi2 ~]# systemctl restart mysqld
注意：如果防火墙是打开的，记得添加mysql的端口号。
[root@youxi2 ~]# firewall-cmd --permanent --zone=public --add-port={3306,33062}/tcp
success
[root@youxi2 ~]# firewall-cmd --reload
success
[root@youxi2 ~]# firewall-cmd --zone=public --list-ports
3306/tcp 33062/tcp修改master信息，构建组复制（group replication）集群信息
mysql> change master to master_user='repl',master_password='12345678' for channel 'group_replication_recovery'; query ok, 0 rows affected, 2 warnings (0.05 sec)
安装组复制（group replication）插件
mysql> install plugin group_replication soname 'group_replication.so'; query ok, 0 rows affected (0.35 sec)
把youxi2加到之前的组复制（group replication）
mysql> set global group_replication_allow_local_disjoint_gtids_join=on; query ok, 0 rows affected, 1 warning (0.00 sec) mysql> start group_replication; query ok, 0 rows affected, 1 warning (5.92 sec)
查看到添加到组复制集群的服务器信息
mysql> select * from performance_schema.replication_group_members; +---------------------------+--------------------------------------+-------------+-------------+--------------+ | channel_name | member_id | member_host | member_port | member_state | +---------------------------+--------------------------------------+-------------+-------------+--------------+ | group_replication_applier | 8fbf8b41-84fe-11e9-897e-000c29f27e52 | youxi2 | 3306 | online | | group_replication_applier | c9e3662b-9020-11e9-94aa-000c29721e89 | youxi1 | 3306 | online | +---------------------------+--------------------------------------+-------------+-------------+--------------+ 2 rows in set (0.00 sec)
3）youxi3的配置与youxi2的配置几乎一样，只需在/etc/my.cnf修改server-id和loose-group_replication_local_address即可。
查看一下组复制集群信息
mysql> select * from performance_schema.replication_group_members; +---------------------------+--------------------------------------+-------------+-------------+--------------+ | channel_name | member_id | member_host | member_port | member_state | +---------------------------+--------------------------------------+-------------+-------------+--------------+ | group_replication_applier | 74df3399-91b8-11e9-be5f-000c299fdf40 | youxi3 | 3306 | online | | group_replication_applier | 8fbf8b41-84fe-11e9-897e-000c29f27e52 | youxi2 | 3306 | online | | group_replication_applier | c9e3662b-9020-11e9-94aa-000c29721e89 | youxi1 | 3306 | online | +---------------------------+--------------------------------------+-------------+-------------+--------------+ 3 rows in set (0.01 sec)
注意：如果防火墙是打开的，记得添加mysql的端口号。
[root@youxi3 ~]# firewall-cmd --permanent --zone=public --add-port=3306/tcp success [root@youxi3 ~]# firewall-cmd --permanent --zone=public --add-port=33063/tcp success [root@youxi3 ~]# firewall-cmd --reload success [root@youxi3 ~]# firewall-cmd --zone=public --list-ports 3306/tcp 33063/tcp
4）测试
在youxi1上创建数据
mysql> create database test_db; query ok, 1 row affected (0.00 sec) mysql> use test_db; database changed mysql> create table user_tb(id int key,name varchar(20)); //id是主键，引擎默认是innodb query ok, 0 rows affected (0.02 sec) mysql> insert into user_tb values(1,'zhangsan'); query ok, 1 row affected (0.08 sec)
在youxi2上查看
mysql> select * from test_db.user_tb; +----+----------+ | id | name | +----+----------+ | 1 | zhangsan | +----+----------+ 1 row in set (0.00 sec)
在youxi3上查看
mysql> select * from test_db.user_tb; +----+----------+ | id | name | +----+----------+ | 1 | zhangsan | +----+----------+ 1 row in set (0.00 sec)
5）那么怎么区分主从服务器
mgr区分主从服务器使用show variables like '%read_only%';查看read_only相关参数。如果是主服务器（youxi1），会显示如下：
mysql> show variables like '%read_only%'; +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | off | | super_read_only | off | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.00 sec)
如果是从服务器（youxi2）会显示如下：
mysql> show variables like '%read_only%'; +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | on | | super_read_only | on | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.01 sec)
6）查看当前服务器的组复制集群参数设置列表
mysql> show variables like 'group_replication%'; +----------------------------------------------------+----------------------------------------+ | variable_name | value | +----------------------------------------------------+----------------------------------------+ | group_replication_allow_local_disjoint_gtids_join | off | | group_replication_allow_local_lower_version_join | off | | group_replication_auto_increment_increment | 7 | | group_replication_bootstrap_group | off | | group_replication_components_stop_timeout | 31536000 | | group_replication_compression_threshold | 1000000 | | group_replication_enforce_update_everywhere_checks | off | | group_replication_exit_state_action | read_only | | group_replication_flow_control_applier_threshold | 25000 | | group_replication_flow_control_certifier_threshold | 25000 | | group_replication_flow_control_mode | quota | | group_replication_force_members | | | group_replication_group_name | ce9be252-2b71-11e6-b8f4-00212844f856 | | group_replication_group_seeds | youxi1:33061,youxi2:33062,youxi3:33063 | | group_replication_gtid_assignment_block_size | 1000000 | | group_replication_ip_whitelist | automatic | | group_replication_local_address | youxi1:33061 | | group_replication_member_weight | 50 | | group_replication_poll_spin_loops | 0 | | group_replication_recovery_complete_at | transactions_applied | | group_replication_recovery_reconnect_interval | 60 | | group_replication_recovery_retry_count | 10 | | group_replication_recovery_ssl_ca | | | group_replication_recovery_ssl_capath | | | group_replication_recovery_ssl_cert | | | group_replication_recovery_ssl_cipher | | | group_replication_recovery_ssl_crl | | | group_replication_recovery_ssl_crlpath | | | group_replication_recovery_ssl_key | | | group_replication_recovery_ssl_verify_server_cert | off | | group_replication_recovery_use_ssl | off | | group_replication_single_primary_mode | on | | group_replication_ssl_mode | disabled | | group_replication_start_on_boot | off | | group_replication_transaction_size_limit | 0 | | group_replication_unreachable_majority_timeout | 0 | +----------------------------------------------------+----------------------------------------+ 36 rows in set (0.00 sec)
7）如果主服务器出问题，mgr会自动切换主服务器
将youxi1的mysqld人为关闭
[root@youxi1 ~]# systemctl stop mysqld
之后前往youxi2和youxi3查看谁是主服务器
mysql> show variables like '%read_only%'; //这是youxi2的 +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | on | | super_read_only | on | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.01 sec) mysql> show variables like '%read_only%'; //这是youxi3的 +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | off | | super_read_only | off | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.02 sec)
可以看到youxi3变成了主服务器，那么尝试在youxi3中插入数据
mysql> insert into test_db.user_tb values(2,'lisi'); query ok, 1 row affected (0.14 sec)
再到youxi2中查看数据
mysql> select * from test_db.user_tb; +----+----------+ | id | name | +----+----------+ | 1 | zhangsan | | 2 | lisi | +----+----------+ 2 rows in set (0.00 sec)
(2).多主模式
1）在创建时就启用多主模式
在创建时就启用多主模式只需在修改配置文件/etc/my.cnf时多加两行参数。其余保持不变
loose-group_replication_single_primary_mode=off //关闭单master模式 loose-group_replication_enforce_update_everywhere_checks=on //多主一致性检查
2）由单主模式改为多主模式
由单主改为多主时，一样需要所有服务器配置信息增加两行参数，为了下次开启就是多主模式
loose-group_replication_single_primary_mode=off //关闭单master模式 loose-group_replication_enforce_update_everywhere_checks=on //开启多主一致性检查
然后全部服务器停止组复制（group_replication）集群，并设置参数
mysql> stop group_replication; query ok, 0 rows affected (9.51 sec) mysql> set global group_replication_single_primary_mode=off; //关闭单主模式 query ok, 0 rows affected (0.00 sec) mysql> set global group_replication_enforce_update_everywhere_checks=on; //开启多主一致性检查 query ok, 0 rows affected (0.00 sec)
选择其中一台引导组复制（group_replication）集群
mysql> set global group_replication_bootstrap_group=on; query ok, 0 rows affected (0.00 sec) mysql> start group_replication; query ok, 0 rows affected (2.13 sec) mysql> set global group_replication_bootstrap_group=off; query ok, 0 rows affected (0.01 sec)
剩下的开启组复制（group_replication）即可
mysql> start group_replication; query ok, 0 rows affected, 1 warning (6.05 sec)
最后查看非引导组复制的服务器
mysql> select * from performance_schema.replication_group_members; +---------------------------+--------------------------------------+-------------+-------------+--------------+ | channel_name | member_id | member_host | member_port | member_state | +---------------------------+--------------------------------------+-------------+-------------+--------------+ | group_replication_applier | 74df3399-91b8-11e9-be5f-000c299fdf40 | youxi3 | 3306 | online | | group_replication_applier | 8fbf8b41-84fe-11e9-897e-000c29f27e52 | youxi2 | 3306 | online | | group_replication_applier | c9e3662b-9020-11e9-94aa-000c29721e89 | youxi1 | 3306 | online | +---------------------------+--------------------------------------+-------------+-------------+--------------+ 3 rows in set (0.00 sec) mysql> show variables like '%read_only%'; +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | off | | super_read_only | off | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.01 sec)
(3).如果宕机了
停掉youxi1的mysqld模拟宕机
[root@youxi1 ~]# systemctl stop mysqld
这时候查看youxi2和youxi3谁是新的master
[root@youxi2 ~]# mysql -uroot -p123456 mysql> show variables like '%read_only%'; //这是youxi2的 +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | on | | super_read_only | on | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.00 sec) [root@youxi3 ~]# mysql -uroot -p123456 mysql> show variables like '%read_only%'; //这是youxi3的，可以看出youxi3成为了新的master +-----------------------+-------+ | variable_name | value | +-----------------------+-------+ | innodb_read_only | off | | read_only | off | | super_read_only | off | | transaction_read_only | off | | tx_read_only | off | +-----------------------+-------+ 5 rows in set (0.00 sec)
在youxi3上写入数据，这是因为生产环境数据库是一直在使用的状态，不可能等你修复后再用
[root@youxi3 ~]# mysql -uroot -p123456 mysql> insert into test_db.user_tb values(2,'lisi'); query ok, 1 row affected (0.03 sec) mysql> select * from test_db.user_tb; +----+----------+ | id | name | +----+----------+ | 1 | zhangsan | | 2 | lisi | +----+----------+ 2 rows in set (0.00 sec)
将修好的youxi1添加回复制组
[root@youxi1 ~]# systemctl start mysqld [root@youxi1 ~]# mysql -uroot -p123456 mysql> select * from performance_schema.replication_group_members; +---------------------------+-----------+-------------+-------------+--------------+ | channel_name | member_id | member_host | member_port | member_state | +---------------------------+-----------+-------------+-------------+--------------+ | group_replication_applier | | | null | offline | +---------------------------+-----------+-------------+-------------+--------------+ 1 row in set (0.00 sec) mysql> change master to master_user='repl',master_password='12345678' for channel 'group_replication_recovery'; //这一步是为了以防万一， query ok, 0 rows affected, 2 warnings (0.01 sec) mysql> set global group_replication_allow_local_disjoint_gtids_join=on; //将这台服务器重新添加进复制组 query ok, 0 rows affected (0.00 sec) mysql> start group_replication; query ok, 0 rows affected (3.36 sec) mysql> select * from performance_schema.replication_group_members; //查看是否加入复制组 +---------------------------+--------------------------------------+-------------+-------------+--------------+ | channel_name | member_id | member_host | member_port | member_state | +---------------------------+--------------------------------------+-------------+-------------+--------------+ | group_replication_applier | 07c6f159-964f-11e9-b2c7-000c2934a723 | youxi3 | 3306 | online | | group_replication_applier | 8247f048-962f-11e9-a210-000c2975fa5d | youxi2 | 3306 | online | | group_replication_applier | 8b703193-962a-11e9-b582-000c29e6d627 | youxi1 | 3306 | online | +---------------------------+--------------------------------------+-------------+-------------+--------------+ 3 rows in set (0.00 sec) mysql> select * from test_db.user_tb; //查看是否同步数据，没有同步请耐心等待，时间可能会长点 +----+----------+ | id | name | +----+----------+ | 1 | zhangsan | | 2 | lisi | +----+----------+ 2 rows in set (0.00 sec)
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