mysql group replication 主节点宕机恢复

一、mysql group replication 生来就要面对两个问题：

　　一、主节点宕机如何恢复。

　　二、多数节点离线的情况下、余下节点如何继续承载业务。

　　在这里我们只讨论第一个问题、也就是说当主结点宕机之后、我们怎么把它从新加入到高可用集群中去。这个问题又可以细分成

　　两种情况：

　　　　1、温和打击：主结点的数据还在、宕机期间集群中的其它结点的binlog日志也都还在

　　　　　　　　　　这种情况下重新启动mysql group replication 就可修复问题。

　　　　2、毁灭打击：主结点的数据都没有了

　　　　　　　　　　这种情况下要从其余结点备份恢复宕机结点、然后再重启mysql group replication 就可修复问题。

　　详细的修复步骤请看后面的例子

二、环境介绍：

　　环境简介

主机名　　　　　　　　　ip地址　　　　　　　　mgr角色

mtls17　　　　　　　　10.186.19.17　　　　　　primary　　　　

mtls18　　　　　　　　10.186.19.18　　　　　　seconde

mtls19　　　　　　　　10.186.19.19　　　　　　seconde

　　集群状态：

mysql> select * from replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 12b6f8d9-d655-11e7-936a-9a17854b700d | mtls17      |        3306 | ONLINE       |
| group_replication_applier | 12bfe200-d655-11e7-a264-1e1b3511358e | mtsl18      |        3306 | ONLINE       |
| group_replication_applier | 1453bcac-d655-11e7-a503-8a7c439b72d9 | mtls19      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
3 rows in set (0.00 sec)

mysql> show global status like 'group_replication_primary_member';
+----------------------------------+--------------------------------------+
| Variable_name                    | Value                                |
+----------------------------------+--------------------------------------+
| group_replication_primary_member | 12b6f8d9-d655-11e7-936a-9a17854b700d |
+----------------------------------+--------------------------------------+
1 row in set (0.00 sec)

　　说明：

　　由上面的信息可以看出mtls17上的mysql为集群当前的primary结点、并且集群的各结点的状态正常。

三、情况下的故障模拟 + 解决：

　　1、模拟mtls17结点宕机

ps -ef | grep mysql
mysql    24125     1  0 00:04 ?        00:00:14 /usr/local/mysql/bin/mysqld --defaults-file=/etc/my.cnf
root     26125 22481  0 00:36 pts/0    00:00:00 grep --color=auto mysql
[root@mtls17 data]# kill -9 24125
[root@mtls17 data]# ps -ef | grep mysql
root     26128 22481  0 00:37 pts/0    00:00:00 grep --color=auto mysql

　　

　　2、查看余下两个结点的情况

mysql> melect * from replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 12bfe200-d655-11e7-a264-1e1b3511358e | mtsl18      |        3306 | ONLINE       |
| group_replication_applier | 1453bcac-d655-11e7-a503-8a7c439b72d9 | mtls19      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
2 rows in set (0.00 sec)

mysql> show global status like 'group_replication_primary_member';
+----------------------------------+--------------------------------------+
| Variable_name                    | Value                                |
+----------------------------------+--------------------------------------+
| group_replication_primary_member | 12bfe200-d655-11e7-a264-1e1b3511358e |
+----------------------------------+--------------------------------------+
1 row in set (0.00 sec)

　　由上面可以看出在mtls17结点上的mysql被kill掉之后、余下的两个结点组成了新的集群、并且mtls18上的mysql

　　成为了primary

　　

　　3、解决primary宕机恢复的问题

systemctl start mysql
[root@mtls17 data]# mysql -uroot -pmtls0352
mysql: [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 3
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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> start group_replication;
Query OK, 0 rows affected (4.03 sec)

mysql>

　　4、检查问题是否正常解决

select * from replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 12b6f8d9-d655-11e7-936a-9a17854b700d | mtls17      |        3306 | ONLINE       |
| group_replication_applier | 12bfe200-d655-11e7-a264-1e1b3511358e | mtsl18      |        3306 | ONLINE       |
| group_replication_applier | 1453bcac-d655-11e7-a503-8a7c439b72d9 | mtls19      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
3 rows in set (0.00 sec)

mysql> show global status like 'group_replication_primary_member';
+----------------------------------+--------------------------------------+
| Variable_name                    | Value                                |
+----------------------------------+--------------------------------------+
| group_replication_primary_member | 12bfe200-d655-11e7-a264-1e1b3511358e |
+----------------------------------+--------------------------------------+
1 row in set (0.00 sec)

　　总论：之前的主结点在宕机之后、通过重启服务、重启mysql-group-replication成功的解决了问题。

四、模拟primary结点上的数据已经丢失的情况下、如果恢复结点：

　　1、退出服务、删除数据

[root@mtsl18 ~]# ps -ef | grep mysql
mysql    10843     1  0 00:04 ?        00:00:19 /usr/local/mysql/bin/mysqld --defaults-file=/etc/my.cnf
root     13290  9197  0 00:50 pts/0    00:00:00 grep --color=auto mysql
[root@mtsl18 ~]# kill -9 10843
[root@mtsl18 ~]# rm -rf /database/mysql/data/3306
[root@mtsl18 ~]# ps -ef | grep mysql
root     13339  9197  0 00:50 pts/0    00:00:00 grep --color=auto mysql

　　这个实验是接着情况一做下去的、所以primary在mtls18上、所以我们在mtls18上做退出服务、删除数据的动作

　　2、查看集群的状态：

mysql> select * from replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 12b6f8d9-d655-11e7-936a-9a17854b700d | mtls17      |        3306 | ONLINE       |
| group_replication_applier | 1453bcac-d655-11e7-a503-8a7c439b72d9 | mtls19      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
2 rows in set (0.00 sec)

mysql> show global status like 'group_replication_primary_member';
+----------------------------------+--------------------------------------+
| Variable_name                    | Value                                |
+----------------------------------+--------------------------------------+
| group_replication_primary_member | 12b6f8d9-d655-11e7-936a-9a17854b700d |
+----------------------------------+--------------------------------------+
1 row in set (0.01 sec)

　　说明：当mtls18宕机后primary就从mtls18切到了mtls17上去了

　　3、通过meb备份mtls19用于还原宕机的mtls18

mysqlbackup --defaults-file=/etc/my.cnf --with-timestamp \
--host=localhost --user=root --password=mtls0352 \
--backup-dir=/tmp/ --backup-image=/tmp/2017-12-01T12:30:00.mbi --no-history-logging \
backup-to-image

MySQL Enterprise Backup version 4.1.0 Linux-2.6.39-400.215.10.el5uek-x86_64 [2017/03/01]
Copyright (c) 2003, 2017, Oracle and/or its affiliates. All Rights Reserved.

171201 01:01:36 MAIN    INFO: A thread created with Id '140141436434240'
171201 01:01:36 MAIN    INFO: Starting with following command line ...
mysqlbackup --defaults-file=/etc/my.cnf --with-timestamp --host=localhost
--user=root --password=xxxxxxxx --backup-dir=/tmp/
--backup-image=/tmp/2017-12-01T12:30:00.mbi --no-history-logging
backup-to-image

171201 01:01:36 MAIN    INFO:
171201 01:01:36 MAIN    INFO: MySQL server version is '5.7.20-log'
.......
........
171201 01:01:40 MAIN    INFO: Full Image Backup operation completed successfully.
171201 01:01:40 MAIN    INFO: Backup image created successfully.
171201 01:01:40 MAIN    INFO: Image Path = /tmp/2017-12-01T12:30:00.mbi
171201 01:01:40 MAIN    INFO: MySQL binlog position: filename mysql-bin.000002, position 1082

-------------------------------------------------------------
Parameters Summary
-------------------------------------------------------------
Start LSN                  : 2609664
End LSN                    : 2610075
-------------------------------------------------------------

mysqlbackup completed OK!

　　4、传输备份到mtls18

scp /tmp/2017-12-01T12:30:00.mbi mtls18:/tmp/

　　5、还原备份

mysqlbackup --defaults-file=/etc/my.cnf --backup-image=/tmp/2017-12-01T12:30:00.mbi \
> --backup-dir=/tmp/ --datadir=/database/mysql/data/3306/ \
> copy-back-and-apply-log
MySQL Enterprise Backup version 4.1.0 Linux-2.6.39-400.215.10.el5uek-x86_64 [2017/03/01]
Copyright (c) 2003, 2017, Oracle and/or its affiliates. All Rights Reserved.

171201 01:09:59 MAIN    INFO: A thread created with Id '140530650736448'
171201 01:09:59 MAIN    INFO: Starting with following command line ...
mysqlbackup --defaults-file=/etc/my.cnf
--backup-image=/tmp/2017-12-01T12:30:00.mbi --backup-dir=/tmp/
--datadir=/database/mysql/data/3306/ copy-back-and-apply-log

171201 01:09:59 MAIN    INFO:
IMPORTANT: Please check that mysqlbackup run completes successfully.
.....
.....
171201 01:10:08 PCR1    INFO: The first data file is '/database/mysql/data/3306/ibdata1'
and the new created log files are at '/database/mysql/data/3306/'
171201 01:10:08 MAIN    INFO: MySQL server version is '5.7.20-log'
171201 01:10:08 MAIN    INFO: Restoring ...5.7.20-log version
171201 01:10:08 MAIN    INFO: Apply-log operation completed successfully.
171201 01:10:08 MAIN    INFO: Full Backup has been restored successfully.

mysqlbackup completed OK!

　　6、重启mtls18上的mysql

[root@mtsl18 tmp]# chown -R mysql:mysql /database/mysql/data/3306
[root@mtsl18 tmp]# systemctl start mysql
[root@mtsl18 tmp]# ps -ef | grep mysql
mysql    14205     1 24 01:11 ?        00:00:01 /usr/local/mysql/bin/mysqld --defaults-file=/etc/my.cnf
root     14237  9197  0 01:11 pts/0    00:00:00 grep --color=auto mysql

　　7、重启mysql group replication

mysql -uroot -pmtls0352
mysql: [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 4
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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> reset master;
Query OK, 0 rows affected (0.10 sec)

mysql> reset slave;
Query OK, 0 rows affected (0.00 sec)

mysql> set sql_log_bin=0;
Query OK, 0 rows affected (0.00 sec)

mysql> source /database/mysql/data/3306/backup_gtid_executed.sql ;
Query OK, 0 rows affected (0.10 sec)

mysql> set sql_log_bin=1;
Query OK, 0 rows affected (0.00 sec)

mysql> change master to
->     master_user='mgr_usr',
->     master_password='mgr10352'
->     for channel 'group_replication_recovery';
Query OK, 0 rows affected, 2 warnings (0.21 sec)

mysql> start group_replication;
Query OK, 0 rows affected (3.46 sec)

　　8、检查集群的状态是否正常

mysql> select * from replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 12b6f8d9-d655-11e7-936a-9a17854b700d | mtls17      |        3306 | ONLINE       |
| group_replication_applier | 1453bcac-d655-11e7-a503-8a7c439b72d9 | mtls19      |        3306 | ONLINE       |
| group_replication_applier | 85f82fce-d65e-11e7-9e92-1e1b3511358e | mtsl18      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
3 rows in set (0.01 sec)

mysql> show global status like 'group_replication_primary_member';
+----------------------------------+--------------------------------------+
| Variable_name                    | Value                                |
+----------------------------------+--------------------------------------+
| group_replication_primary_member | 12b6f8d9-d655-11e7-936a-9a17854b700d |
+----------------------------------+--------------------------------------+
1 row in set (0.01 sec)

五、总结：

　　对于两种primary宕故障的修复总结：

　　　　1、数据没有丢、binlog日志也没有丢 那直接重启mysql group replication 就行、它会自动修复问题。

　　　　2、数据丢失的情况、先备份还原-->重启mysql group replication 就行。

　　对于mysql group replication 维护操作复杂性的总结：　　

　　　　总的来说mysql group replication 对dba还是比较友好的、几个小小的操作就能恢复故障的集群。

六、我写的关于mysql group replication 的相关文章　

　　1、mysql group replication 安装与配置详解：http://www.cnblogs.com/JiangLe/p/6727281.html#3849996

　　2、mysql group replication 在mysql-5.7.20版本下的可用性报告：http://www.cnblogs.com/JiangLe/p/7809229.html

　　3、mysql group replication 主节宕机点恢复 https://i.cnblogs.com/EditPosts.aspx?postid=7941929

　　4、mysql group replication 多数据结点丢失情况下的恢复

　　5、我写的全自动化安装mysql-group-replication 开源工具 https://github.com/Neeky/mysqltools

----