MGR基于binlog+row广播方式来多个节点的数据强一致性同步和percona提出来的PXC高可用架构相似功能
本次搭建搭建采取3节点：
172.18.0.150,作为第一节点
172.18.0.151,作为第二节点，直接加入
172.18.0.152作为第三节点，通过mysqldump导入数据加入

1.配置相关参数，并启动数据库
在my.cnf文件中添加如下参数，其中注释了基本参数已经有的

#######################:for MGR##############################
#server_id
#gtid_mode
#enforce_gtid_consistency
binlog_checksum=none
#log_bin
#log_slave_updates
#binlog_format=row
master_info_repository=table
relay_log_info_repository=table

transaction_write_set_extraction=XXHASH64
loose-group_replication_group_name='d91ac177-aaf9-4707-b8a0-a78fdcfdd7c4'
loose-group_replication_start_on_boot=off
loose-group_replication_local_address="172.18.0.150:23310"
loose-group_replication_group_seeds="172.18.0.150:23310,172.18.0.151:23310,172.18.0.152:23310"
loose-group_replication_bootstrap_group=off

参数简单解释
group_replication_group_name 这个参数注意在长度和格式和uuid相似，我这里利用linux下uuidgen工具生成的
group_replication_bootstrap_group=off建议配置关闭，只在第一节点启动设置成on，一般情况下建议off，以便故障时，节点间的正常选举

/usr/local/mysql/bin/mysqld --defaults-file=/data/mysql/my_mgr.cnf &

2.设置用户信息，并加载插件

mysql> set sql_log_bin=0;
Query OK, 0 rows affected (0.00 sec)
mysql> create user 'repl'@'%' identified by 'repl';
Query OK, 0 rows affected (0.00 sec)
mysql> grant replication slave on *.* to 'repl'@'%';
Query OK, 0 rows affected (0.00 sec)
mysql> set sql_log_bin=1;
Query OK, 0 rows affected (0.00 sec)
mysql> change master to master_user='repl',master_password='repl' for channel 'group_replication_recovery';
Query OK, 0 rows affected, 2 warnings (0.15 sec)
mysql> install plugin group_replication soname 'group_replication.so';
Query OK, 0 rows affected (0.09 sec)

mysql> show plugins;
+----------------------------+----------+--------------------+----------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+----------------------+---------+
...................
| group_replication | ACTIVE | GROUP REPLICATION | group_replication.so | GPL |
+----------------------------+----------+--------------------+----------------------+---------+

3.启动第一节点

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 (2.16 sec)
error.log日志信息如下：
2019-05-30T10:17:16.684171+08:00 14 [Note] Plugin group_replication reported: 'Only one server alive. Declaring this server as online within the replication group'
2019-05-30T10:17:16.684300+08:00 0 [Note] Plugin group_replication reported: 'Group membership changed to trsen150:3310 on view 15591826366838192:1.'
2019-05-30T10:17:16.994818+08:00 0 [Note] Plugin group_replication reported: 'This server was declared online within the replication group'
2019-05-30T10:17:16.994917+08:00 0 [Note] Plugin group_replication reported: 'A new primary with address trsen150:3310 was elected, enabling conflict detection until the new primary applies all relay logs.'
2019-05-30T10:17:16.994978+08:00 16 [Note] Plugin group_replication reported: 'This server is working as primary member.'
说明第一个节点已经成功启动

4.确认节点信息

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 7bfaf693-827d-11e9-a39a-0242ac120096 | trsen150 | 3310 | ONLINE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
1 row in set (0.00 sec)

mysql> select @@server_uuid;
+--------------------------------------+
| @@server_uuid |
+--------------------------------------+
| 7bfaf693-827d-11e9-a39a-0242ac120096 |
+--------------------------------------+
1 row in set (0.00 sec)
mysql> set global group_replication_bootstrap_group=off;
Query OK, 0 rows affected (0.00 sec)

5.在binlog都有情况添加第二节点（这种方式只在新环境搭建中操作）
a.初始化并启动db

/usr/local/mysql/bin/mysqld --defaults-file=/data/mysql/my_mgr.cnf --initialize-insecure
/usr/local/mysql/bin/mysqld --defaults-file=/data/mysql/my_mgr.cnf &

b.创建用户并加载插件（建议通道名默认用group_replication_recovery，我在测试中更改名，加节点时会报错，channel不正确）

mysql> set sql_log_bin=0;
mysql> create user 'repl'@'%' identified by 'repl';
mysql> grant replication slave on *.* to 'repl'@'%';
mysql> set sql_log_bin=1;
mysql> change master to master_user='repl',master_password='repl' for channel 'group_replication_recovery';
mysql> install plugin group_replication soname 'group_replication.so';

c.启动并核实信息

mysql> start group_replication;
mysql> SELECT b.member_id, b.member_host, b.member_port FROM performance_schema.global_status a INNER JOIN performance_schema.replication_group_members b ON a.variable_value = b.member_id WHERE a.variable_name= 'group_replication_primary_member';
+--------------------------------------+-------------+-------------+
| member_id | member_host | member_port |
+--------------------------------------+-------------+-------------+
| 7bfaf693-827d-11e9-a39a-0242ac120096 | trsen150 | 3310 |
+--------------------------------------+-------------+-------------+
mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 7bfaf693-827d-11e9-a39a-0242ac120096 | trsen150 | 3310 | ONLINE |
| group_replication_applier | 8e0a2a84-8283-11e9-89bb-0242ac120097 | trsen151 | 3310 | ONLINE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+

d.测试
在150节点create database，同步到151上来

6.利用mysqldump备份加入第三节点（线上小库环境）

a.利用sysbench造点数据和并发上来，然后purge一些binlog，来模拟线上情景

./sysbench --mysql-user=trsen --mysql-db=trsen --mysql-password=trsen \
--mysql-host=172.18.0.150 --mysql-port=3310 --test=tests/db/oltp.lua --oltp_tables_count=5 \
--oltp-table-size=100000 --rand-init=on prepare

./sysbench --mysql-user=trsen --mysql-db=trsen --mysql-password=trsen --mysql-host=172.18.0.150 --mysql-port=3310 \
--test=tests/db/oltp.lua --oltp_tables_count=5 \
--oltp-table-size=100000 --num-threads=8 --oltp-read-only=off \
--report-interval=10 --rand-type=uniform --max-time=12000 \
--max-requests=0 --percentile=99 run

b.dump数据

/usr/local/mysql/bin/mysqldump --single-transaction --master-data=2 -A -S /tmp/mysql3310.sock>db150_`date +%M%m%d`.sql

c.导入数据

/usr/local/mysql/bin/mysql -uroot -p -S /tmp/mysql3310.sock <db150_20190530.sql

d.设置gtid及change master
这里的gitd信息来备份文件中，一般情况无需手工设置，做这个操作之前，建议reset master（在新加节点上，一定不要搞错了）

mysql> SET @@GLOBAL.GTID_PURGED='d91ac177-aaf9-4707-b8a0-a78fdcfdd7c4:1-36127';
mysql> change master to master_user='repl',master_password='repl' for channel 'group_replication_recovery';

e.启动节点3，可以发现正在同步数据

mysql> start group_replication;
Query OK, 0 rows affected (2.77 sec)
mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 06691df9-82ac-11e9-9243-0242ac120098 | trsen152 | 3310 | RECOVERING |
| group_replication_applier | 7bfaf693-827d-11e9-a39a-0242ac120096 | trsen150 | 3310 | ONLINE |
| group_replication_applier | 8e0a2a84-8283-11e9-89bb-0242ac120097 | trsen151 | 3310 | ONLINE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+

查看single模式下当前的主节点是谁？

mysql> select * from performance_schema.replication_group_members where member_id=(select variable_value from performance_schema.global_status where variable_name='group_replication_primary_member');
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 7bfaf693-827d-11e9-a39a-0242ac120096 | trsen150 | 3310 | ONLINE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+