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MySQL高可用方案MHA自动Failover与手动Failover的实践及原理

[日期:2017-05-25] 来源:Linux社区  作者:ivictor [字体: ]

集群信息

角色                            IP地址                ServerID      类型

Master                        192.168.244.10  1                写入

Candicate master          192.168.244.20  2                读

Slave                          192.168.244.30  3                读

Monitor host                192.168.244.40                      监控集群组

MHA具体的搭建步骤和原理,可参考另外一篇文章:

MySQL高可用方案MHA的部署和原理  http://www.linuxidc.com/Linux/2017-05/144086.htm

自动Failover

为了通过MHA的日志清晰判断MHA自动Failover的实现原理,需模拟如下场景:

当主库发生故障时,master中还有一部分binlog日志没有传输到Candicate master和Slave上,且Slave上的二进制日志多于Candicate master上。

尝试了几种方案,总算如愿以偿。

方案一:

     1. 关闭Candicate master和Slave的主从复制。

     2. 通过存储过程生成测试数据

     3. 开启Candicate master和Slave的主从复制并kill掉master的mysqld进程,模拟主库发生故障,进行自动failover操作

     为此,还特意写了个脚本,可惜的是,效果并不理想,在自动Failover的过程中,显示MHA Manager到master的“SSH is NOT reachable”。

方案二:

     通过tc命令对Candicate master和Slave的网卡分别设置不同的传输速率,确保发送到Candicate master的日志量小于Slave上的。

     很可惜,效果同方案一一样。

方案三:

      在主从复制中,直接关闭master的mysqld数据库。

      但是,通过这样方式,并不会实现Slave上的二进制日志多于Candicate master的效果。

方案四:

      通过截取relay log,在关掉slave的情况下,修改master.info和relay-log.info的位置点来人为制造Candicate master的日志量小于Slave的。

      事后想想,其实这样的方法就等同于先关闭Candicate master的主从复制,再在master上执行一段操作,再关闭slave上的主从复制,再在master上执行一段操作。

      这样不就实现了master的binlog > slave 的relay log > Candicate master的relay log。

      方案四总算如愿以偿

下面通过方案四看看MHA的实现原理

1. 创建测试表,并插入测试数据

mysql> create table sbtest.b(id int,name varchar(10)); Query OK,0 rows affected (0.12 sec)

mysql
> insert into sbtest.b values(1,'a');
Query OK,
1 row affected (0.00 sec)

mysql
> insert into sbtest.b values(2,'b');
Query OK,
1 row affected (0.01 sec)

mysql
> insert into sbtest.b values(3,'c');
Query OK,
1 row affected (0.00 sec)

mysql
> insert into sbtest.b values(4,'d');
Query OK,
1 row affected (0.00 sec)

mysql
> insert into sbtest.b values(5,'e');
Query OK,
1 row affected (0.01 sec)

2. 分别查看master上binlog的内容,slave上relay log的内容

   Master

 
mysql> show binlog events;
+------------------+------+-------------+-----------+-------------+------------------------------------------------+
| Log_name         | Pos  | Event_type  | Server_id | End_log_pos | Info                                           |
+------------------+------+-------------+-----------+-------------+------------------------------------------------+
| mysql-bin.000001 |    4 | Format_desc |         1 |         120 | Server ver: 5.6.31-log, Binlog ver: 4          |
| mysql-bin.000001 |  120 | Query       |         1 |         238 | create table sbtest.b(id int,name varchar(10)) |
| mysql-bin.000001 |  238 | Query       |         1 |         315 | BEGIN                                          |
| mysql-bin.000001 |  315 | Query       |         1 |         421 | insert into sbtest.b values(1,'a')             |
| mysql-bin.000001 |  421 | Xid         |         1 |         452 | COMMIT /* xid=102 */                           |
| mysql-bin.000001 |  452 | Query       |         1 |         529 | BEGIN                                          |
| mysql-bin.000001 |  529 | Query       |         1 |         635 | insert into sbtest.b values(2,'b')             |
| mysql-bin.000001 |  635 | Xid         |         1 |         666 | COMMIT /* xid=103 */                           |
| mysql-bin.000001 |  666 | Query       |         1 |         743 | BEGIN                                          |
| mysql-bin.000001 |  743 | Query       |         1 |         849 | insert into sbtest.b values(3,'c')             |
| mysql-bin.000001 |  849 | Xid         |         1 |         880 | COMMIT /* xid=104 */                           |
| mysql-bin.000001 |  880 | Query       |         1 |         957 | BEGIN                                          |
| mysql-bin.000001 |  957 | Query       |         1 |        1063 | insert into sbtest.b values(4,'d')             |
| mysql-bin.000001 | 1063 | Xid         |         1 |        1094 | COMMIT /* xid=105 */                           |
| mysql-bin.000001 | 1094 | Query       |         1 |        1171 | BEGIN                                          |
| mysql-bin.000001 | 1171 | Query       |         1 |        1277 | insert into sbtest.b values(5,'e')             |
| mysql-bin.000001 | 1277 | Xid         |         1 |        1308 | COMMIT /* xid=106 */                           |
+------------------+------+-------------+-----------+-------------+------------------------------------------------+
17 rows in set (0.01 sec)
 

   Slave

 
mysql> show relaylog events in 'mysqld-relay-bin.000002';
+-------------------------+------+-------------+-----------+-------------+------------------------------------------------+
| Log_name                | Pos  | Event_type  | Server_id | End_log_pos | Info                                           |
+-------------------------+------+-------------+-----------+-------------+------------------------------------------------+
| mysqld-relay-bin.000002 |    4 | Format_desc |         2 |         120 | Server ver: 5.6.31-log, Binlog ver: 4          |
| mysqld-relay-bin.000002 |  120 | Rotate      |         1 |           0 | mysql-bin.000001;pos=120                       |
| mysqld-relay-bin.000002 |  167 | Format_desc |         1 |           0 | Server ver: 5.6.31-log, Binlog ver: 4          |
| mysqld-relay-bin.000002 |  283 | Query       |         1 |         238 | create table sbtest.b(id int,name varchar(10)) |
| mysqld-relay-bin.000002 |  401 | Query       |         1 |         315 | BEGIN                                          |
| mysqld-relay-bin.000002 |  478 | Query       |         1 |         421 | insert into sbtest.b values(1,'a')             |
| mysqld-relay-bin.000002 |  584 | Xid         |         1 |         452 | COMMIT /* xid=102 */                           |
| mysqld-relay-bin.000002 |  615 | Query       |         1 |         529 | BEGIN                                          |
| mysqld-relay-bin.000002 |  692 | Query       |         1 |         635 | insert into sbtest.b values(2,'b')             |
| mysqld-relay-bin.000002 |  798 | Xid         |         1 |         666 | COMMIT /* xid=103 */                           |
| mysqld-relay-bin.000002 |  829 | Query       |         1 |         743 | BEGIN                                          |
| mysqld-relay-bin.000002 |  906 | Query       |         1 |         849 | insert into sbtest.b values(3,'c')             |
| mysqld-relay-bin.000002 | 1012 | Xid         |         1 |         880 | COMMIT /* xid=104 */                           |
| mysqld-relay-bin.000002 | 1043 | Query       |         1 |         957 | BEGIN                                          |
| mysqld-relay-bin.000002 | 1120 | Query       |         1 |        1063 | insert into sbtest.b values(4,'d')             |
| mysqld-relay-bin.000002 | 1226 | Xid         |         1 |        1094 | COMMIT /* xid=105 */                           |
| mysqld-relay-bin.000002 | 1257 | Query       |         1 |        1171 | BEGIN                                          |
| mysqld-relay-bin.000002 | 1334 | Query       |         1 |        1277 | insert into sbtest.b values(5,'e')             |
| mysqld-relay-bin.000002 | 1440 | Xid         |         1 |        1308 | COMMIT /* xid=106 */                           |
+-------------------------+------+-------------+-----------+-------------+------------------------------------------------+
19 rows in set (0.00 sec)

     通过对比master中的binlog event,可以看到show relaylog events中的End_log_pos实际上指的是对应的二进制事件在binlog的位置。

     再来查看Candicate master中对应的relay log的内容

     [root@node2 mysql]# mysqlbinlog mysqld-relay-bin.000002

 
[root@node2 mysql]# mysqlbinlog mysqld-relay-bin.000002
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at 4
#170524 17:16:37 server id 2  end_log_pos 120 CRC32 0x4faba9ae     Start: binlog v 4, server v 5.6.31-log created 170524 17:16:37
BINLOG '
dU8lWQ8CAAAAdAAAAHgAAABAAAQANS42LjMxLWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXAAEGggAAAAICAgCAAAACgoKGRkAAa6p
q08=
'/*!*/;
# at 120
#700101  8:00:00 server id 1  end_log_pos 0 CRC32 0x74c6d70c     Rotate to mysql-bin.000001  pos: 120
# at 167
#170524 17:15:49 server id 1  end_log_pos 0 CRC32 0xed2672eb     Start: binlog v 4, server v 5.6.31-log created 170524 17:15:49
BINLOG '
RU8lWQ8BAAAAdAAAAAAAAAAAAAQANS42LjMxLWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXAAEGggAAAAICAgCAAAACgoKGRkAAety
Ju0=
'/*!*/;
# at 283
#170524 17:17:20 server id 1  end_log_pos 238 CRC32 0xdd48c118     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617440/*!*/;
SET @@session.pseudo_thread_id=2/*!*/;
SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/;
SET @@session.sql_mode=1075838976/*!*/;
SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
/*!\C utf8 *//*!*/;
SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=33/*!*/;
SET @@session.lc_time_names=0/*!*/;
SET @@session.collation_database=DEFAULT/*!*/;
create table sbtest.b(id int,name varchar(10))
/*!*/;
# at 401
#170524 17:17:27 server id 1  end_log_pos 315 CRC32 0xae393750     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617447/*!*/;
BEGIN
/*!*/;
# at 478
#170524 17:17:27 server id 1  end_log_pos 421 CRC32 0x28a781ae     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617447/*!*/;
insert into sbtest.b values(1,'a')
/*!*/;
# at 584
#170524 17:17:27 server id 1  end_log_pos 452 CRC32 0x680f1bfe     Xid = 29
COMMIT/*!*/;
# at 615
#170524 17:17:33 server id 1  end_log_pos 529 CRC32 0x6a1aae7e     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617453/*!*/;
BEGIN
/*!*/;
# at 692
#170524 17:17:33 server id 1  end_log_pos 635 CRC32 0x117786ca     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617453/*!*/;
insert into sbtest.b values(2,'b')
/*!*/;
# at 798
#170524 17:17:33 server id 1  end_log_pos 666 CRC32 0xa8400ec6     Xid = 30
COMMIT/*!*/;
# at 829
#170524 17:17:38 server id 1  end_log_pos 743 CRC32 0x24f9a1d2     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617458/*!*/;
BEGIN
/*!*/;
# at 906
#170524 17:17:38 server id 1  end_log_pos 849 CRC32 0x56fa9e89     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617458/*!*/;
insert into sbtest.b values(3,'c')
/*!*/;
# at 1012
#170524 17:17:38 server id 1  end_log_pos 880 CRC32 0x2ac656d4     Xid = 31
COMMIT/*!*/;
# at 1043
#170524 17:17:44 server id 1  end_log_pos 957 CRC32 0x73a903bf     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617464/*!*/;
BEGIN
/*!*/;
# at 1120
#170524 17:17:44 server id 1  end_log_pos 1063 CRC32 0x171b9b27     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617464/*!*/;
insert into sbtest.b values(4,'d')
/*!*/;
# at 1226
#170524 17:17:44 server id 1  end_log_pos 1094 CRC32 0x47d6fe57     Xid = 32
COMMIT/*!*/;
# at 1257
#170524 17:17:49 server id 1  end_log_pos 1171 CRC32 0x2d37da37     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617469/*!*/;
BEGIN
/*!*/;
# at 1334
#170524 17:17:49 server id 1  end_log_pos 1277 CRC32 0xd2201fa2     Query    thread_id=2    exec_time=0    error_code=0
SET TIMESTAMP=1495617469/*!*/;
insert into sbtest.b values(5,'e')
/*!*/;
# at 1440
#170524 17:17:49 server id 1  end_log_pos 1308 CRC32 0xac1b464e     Xid = 33
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;

     mysql中binlog有个有意思的地方是,位置点其实是也是字节的大小。

     譬如,上面这个relay log中,最后一个位点是# at 1440,算上最后一个commit操作需占用31个字节,所以整个文件的大小是1471,与实际大小吻合。

[root@node2 mysql]# ll mysqld-relay-bin.000002
-rw-rw---- 1 mysql mysql 1471 May 24 17:17 mysqld-relay-bin.000002

3. 通过show slave status查看io thread和sql thread的位置信息

mysql> show slave status\G
*************************** 1. row ***************************
              Slave_IO_State: Waiting
for master to send event
                  Master_Host:
192.168.244.10
                  Master_User: repl
                  Master_Port:
3306
                Connect_Retry:
60
              Master_Log_File: mysql
-bin.000001
          Read_Master_Log_Pos:
1308
              Relay_Log_File: mysqld
-relay-bin.000002
                Relay_Log_Pos:
1471
        Relay_Master_Log_File: mysql
-bin.000001
            Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB:
          Replicate_Do_Table:
      Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                  Last_Errno:
0
                  Last_Error:
                Skip_Counter:
0
          Exec_Master_Log_Pos:
1308
              Relay_Log_Space:
1645
              Until_Condition: None
              Until_Log_File:
                Until_Log_Pos:
0
          Master_SSL_Allowed: No
          Master_SSL_CA_File:
          Master_SSL_CA_Path:
              Master_SSL_Cert:
            Master_SSL_Cipher:
              Master_SSL_Key:
        Seconds_Behind_Master:
0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno:
0
                Last_IO_Error:
              Last_SQL_Errno:
0
              Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
            Master_Server_Id:
1
                  Master_UUID: 2a6365e0
-1d05-11e7-956d-000c29c64704
            Master_Info_File:
/var/lib/mysql/master.info
                    SQL_Delay:
0
          SQL_Remaining_Delay:
NULL
      Slave_SQL_Running_State: Slave has
read all relay log; waiting for the slave I/O thread to update it
          Master_Retry_Count:
86400
                  Master_Bind:
      Last_IO_Error_Timestamp:
    Last_SQL_Error_Timestamp:
              Master_SSL_Crl:
          Master_SSL_Crlpath:
          Retrieved_Gtid_Set:
            Executed_Gtid_Set:
                Auto_Position:
0
1 row in set (0.00 sec)

待会儿需要修改上面Master_Log_File,Read_Master_Log_Pos,Relay_Log_File,Relay_Log_Pos,Relay_Master_Log_File,Exec_Master_Log_Pos的值。

虽然这几个参数的值与master.info和relay-log.info文件是相对应的,

但通过修改master.info和relay-log.info的值,并重启slave,并不会将上述几个参数值修改。

上述几个参数是保存到内存中的,唯一可行的方案是首先关闭slave实例,再修改master.info和relay-log.info文件,然后重新启动mysql实例。

4. 关闭Candicate master实例,剪裁relay log,修改master.info和relay-log.info文件。

   关闭实例

   [root@node2 mysql]# service mysqld stop

   剪裁relay log

   这里,写了个python脚本实现该功能

#!/usr/bin/python

f1
= open('mysqld-relay-bin.000002','r')
f2
= open('tmp_relay_bin','w+')

size1
=f1.read(615)
f2.write(size1)

f1.seek(
1471)
size2
=f1.read()
f2.write(size2)

f1.close()
f2.close()

   在上述脚本size1中,615对应的是insert into sbtest.b values(1,'a')这条记录

   [root@node2 mysql]# python 1.py 

   [root@node2 mysql]# mv tmp_relay_bin mysqld-relay-bin.000002

   修改master.info的内容

   主要是修改第三行

23
mysql-bin.000001
1308

    修改为

23
mysql-bin.000001
452

    修改relay-log.info的内容

    原文件如下:

7
./mysqld-relay-bin.000002
1471
mysql-bin.000001
1308
0
0
1

    修改为:

7
./mysqld-relay-bin.000002
615
mysql-bin.000001
452
0
0
1

   启动slave,注意,配置文件中必须设置skip-slave-start,不然它自动开启主从复制。

   [root@node2 mysql]# service mysqld start

5. 对于slave,同样如此处理,只不过relay log的位置点要靠后些

#!/usr/bin/python

f1 = open('mysqld-relay-bin.000002','r')
f2 = open('tmp_relay_bin','w+')

size1=f1.read(1043)
f2.write(size1)

f1.seek(1471)
size2=f1.read()
f2.write(size2)

f1.close()
f2.close()

   1043对应的是insert into sbtest.b values(3,'c')这条记录

   修改master.info的内容

23
mysql-bin.000001
880

   修改relay-log.info的内容 

7
./mysqld-relay-bin.000002
1043
mysql-bin.000001
880
0
0
1   

6. 开启MHA监控   

# nohup masterha_manager --conf=/etc/masterha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null >
/masterha/app1/manager.log 2>&1 &

# masterha_check_status --conf=/etc/masterha/app1.cnf 

app1 (pid:1615) is running(0:PING_OK), master:192.168.244.10

7. 关闭master实例

# service mysqld stop
 

8. 查看MHA切换日志,了解整个切换过程。

    该日志的时间点与上面relay log的时间点并不吻合,原因在于这个反复测试了很多次。

Sun May 21 20:50:46 2017 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Sun May
21 20:50:46 2017 - [warning] Connection failed 1 time(s)..
Sun May
21 20:50:46 2017 - [info] Executing secondary network check script: /usr/local/bin/masterha_secondary_check -s 192.168.244.20 -s 192.168.244.30 --user=root --master_host=192.168.244.10 --master_ip=192.168.244.10 --master_port=3306  --user=root  --master_host=192.168.244.10  --master_ip=192.168.244.10  --master_port=3306 --master_user=monitor --master_password=monitor123 --ping_type=SELECT
Sun May
21 20:50:46 2017 - [info] Executing SSH check script: save_binary_logs --command=test --start_pos=4 --binlog_dir=/var/lib/mysql --output_file=/tmp/save_binary_logs_test --manager_version=0.56 --binlog_prefix=mysql-bin
Monitoring server
192.168.244.20 is reachable, Master is not reachable from 192.168.244.20. OK.
Sun May
21 20:50:46 2017 - [info] HealthCheck: SSH to 192.168.244.10 is reachable.
Monitoring server
192.168.244.30 is reachable, Master is not reachable from 192.168.244.30. OK.

-- 当monitor检测到master mysqld不可用的时候,即根据masterha_secondary_check脚本从Candicate master和Slave上判断master mysqld的可用性,
根据上面的显示信息,通过192.
168.244.20和192.168.244.30也判断到master mysqld不可用。

如果任意一个slave判断到master mysqld可用,则输出的信息如下:
  #
/usr/local/bin/masterha_secondary_check -s 192.168.244.20 -s 192.168.244.30 --user=root --master_host=192.168.244.10 --master_ip=192.168.244.10 --master_port=3306

  Master is reachable from
192.168.244.20!
 
Sun May
21 20:50:46 2017 - [info] Master is not reachable from all other monitoring servers. Failover should start.
Sun May
21 20:50:47 2017 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Sun May
21 20:50:47 2017 - [warning] Connection failed 2 time(s)..
Sun May
21 20:50:48 2017 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Sun May
21 20:50:48 2017 - [warning] Connection failed 3 time(s)..
Sun May
21 20:50:49 2017 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Sun May
21 20:50:49 2017 - [warning] Connection failed 4 time(s)..
Sun May
21 20:50:49 2017 - [warning] Master is not reachable from health checker!
Sun May
21 20:50:49 2017 - [warning] Master 192.168.244.10(192.168.244.10:3306) is not reachable!
Sun May
21 20:50:49 2017 - [warning] SSH is reachable.

-- 一共判断了4次,均判断master mysqld不可用,但是master主机通过ssh还是能登录上去。
    如果这里显示的是SSH is NOT reachable,则代表master主机也已经宕机了,
    刚开始还以为是通过ssh来判断主机是否宕机,但在之前的测试方案中(具体可见文末),master并没有宕机,这里却显示SSH is NOT reachable.
    通过上面的输出才知道是通过save_binary_logs脚本来判断ssh可用性的。

Sun May
21 20:50:49 2017 - [info] Connecting to a master server failed. Reading configuration file /etc/masterha_default.cnf and /etc/masterha/app1.cnf again, and trying to connect to all servers to check server status..
Sun May
21 20:50:49 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Sun May
21 20:50:49 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Sun May
21 20:50:49 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Sun May
21 20:50:50 2017 - [warning] SQL Thread is stopped(no error) on 192.168.244.20(192.168.244.20:3306)
Sun May
21 20:50:50 2017 - [warning] SQL Thread is stopped(no error) on 192.168.244.30(192.168.244.30:3306)
Sun May
21 20:50:50 2017 - [info] GTID failover mode = 0
Sun May
21 20:50:50 2017 - [info] Dead Servers:
Sun May
21 20:50:50 2017 - [info192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:50 2017 - [info] Alive Servers:
Sun May
21 20:50:50 2017 - [info192.168.244.20(192.168.244.20:3306)
Sun May
21 20:50:50 2017 - [info192.168.244.30(192.168.244.30:3306)
Sun May
21 20:50:50 2017 - [info] Alive Slaves:
Sun May
21 20:50:50 2017 - [info192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:50 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:50 2017 - [info]    Primary candidate for the new Master (candidate_master is set)
Sun May
21 20:50:50 2017 - [info192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:50 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:50 2017 - [info] Checking slave configurations..
Sun May
21 20:50:50 2017 - [info] Checking replication filtering settings..
Sun May
21 20:50:50 2017 - [info]  Replication filtering check ok.
Sun May
21 20:50:50 2017 - [info] Master is down!
Sun May
21 20:50:50 2017 - [info] Terminating monitoring script.
Sun May
21 20:50:50 2017 - [info] Got exit code 20 (Master dead).
Sun May
21 20:50:50 2017 - [info] MHA::MasterFailover version 0.56.
Sun May
21 20:50:50 2017 - [info] Starting master failover.

-- 读取MHA的配置文件,检查slave的相关配置,比如read_only参数,是否设置了复制的过滤规则
  从上面的输出中可以看出,SQL Thread正常停止了并不影响MHA的切换。

Sun May
21 20:50:50 2017 - [info]
Sun May
21 20:50:50 2017 - [info] * Phase 1: Configuration Check Phase..
Sun May
21 20:50:50 2017 - [info]
Sun May
21 20:50:51 2017 - [warning] SQL Thread is stopped(no error) on 192.168.244.20(192.168.244.20:3306)
Sun May
21 20:50:51 2017 - [warning] SQL Thread is stopped(no error) on 192.168.244.30(192.168.244.30:3306)
Sun May
21 20:50:51 2017 - [info] GTID failover mode = 0
Sun May
21 20:50:51 2017 - [info] Dead Servers:
Sun May
21 20:50:51 2017 - [info192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:51 2017 - [info] Checking master reachability via MySQL(double check)...
Sun May
21 20:50:51 2017 - [info]  ok.
Sun May
21 20:50:51 2017 - [info] Alive Servers:
Sun May
21 20:50:51 2017 - [info192.168.244.20(192.168.244.20:3306)
Sun May
21 20:50:51 2017 - [info192.168.244.30(192.168.244.30:3306)
Sun May
21 20:50:51 2017 - [info] Alive Slaves:
Sun May
21 20:50:51 2017 - [info192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:51 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:51 2017 - [info]    Primary candidate for the new Master (candidate_master is set)
Sun May
21 20:50:51 2017 - [info192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:51 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:51 2017 - [info]  Starting SQL thread on 192.168.244.20(192.168.244.20:3306) ..
Sun May
21 20:50:51 2017 - [infodone.
Sun May
21 20:50:51 2017 - [info]  Starting SQL thread on 192.168.244.30(192.168.244.30:3306) ..
Sun May
21 20:50:51 2017 - [infodone.
Sun May
21 20:50:51 2017 - [info] Starting Non-GTID based failover.
Sun May
21 20:50:51 2017 - [info]
Sun May
21 20:50:51 2017 - [info] ** Phase 1: Configuration Check Phase completed.

-- 第一阶段,检查了MHA的配置信息,并再次判断了master的可用性。
  第二阶段,关闭dead master。
  包括执行摘除master上的vip,同时执行shutdown_script脚本,因为该脚本在配置文件中没有定义,故跳过。
 
Sun May
21 20:50:51 2017 - [info]
Sun May
21 20:50:51 2017 - [info] * Phase 2: Dead Master Shutdown Phase..
Sun May
21 20:50:51 2017 - [info]
Sun May
21 20:50:51 2017 - [info] Forcing shutdown so that applications never connect to the current master..
Sun May
21 20:50:51 2017 - [info] Executing master IP deactivation script:
Sun May
21 20:50:51 2017 - [info]  /usr/local/bin/master_ip_failover --orig_master_host=192.168.244.10 --orig_master_ip=192.168.244.10 --orig_master_port=3306 --command=stopssh --ssh_user=root 
Disabling the VIP an old master:
192.168.244.10
SIOCSIFFLAGS: Cannot assign requested address
Sun May
21 20:50:51 2017 - [infodone.
Sun May
21 20:50:51 2017 - [warning] shutdown_script is not set. Skipping explicit shutting down of the dead master.
Sun May
21 20:50:51 2017 - [info] * Phase 2: Dead Master Shutdown Phase completed.
Sun May
21 20:50:51 2017 - [info]

-- 第三阶段
 
3.1 判断哪个slave的二进制日志是最新的。
      通过下面的输出可以看出,所有的slave中,最新的二进制日志位置是mysql
-bin.000001:880(通过show slave status中的Master_Log_File, Read_Master_Log_Pos得到)
      最旧的二进制日志位置是mysql
-bin.000001:452
 
Sun May
21 20:50:51 2017 - [info] * Phase 3: Master Recovery Phase..
Sun May
21 20:50:51 2017 - [info]
Sun May
21 20:50:51 2017 - [info] * Phase 3.1: Getting Latest Slaves Phase..
Sun May
21 20:50:51 2017 - [info]
Sun May
21 20:50:51 2017 - [info] The latest binary log file/position on all slaves is mysql-bin.000001:880
Sun May
21 20:50:51 2017 - [info] Latest slaves (Slaves that received relay log files to the latest):
Sun May
21 20:50:51 2017 - [info192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:51 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:51 2017 - [info] The oldest binary log file/position on all slaves is mysql-bin.000001:452
Sun May
21 20:50:51 2017 - [info] Oldest slaves:
Sun May
21 20:50:51 2017 - [info192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:51 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:51 2017 - [info]    Primary candidate for the new Master (candidate_master is set)
Sun May
21 20:50:51 2017 - [info]

-- 3.2 保存master的binlog
      注意,上面已经判断到slave中最新二进制日志是mysql
-bin.000001:880,所以它把该位置后所有二进制日志都拼接起来,并scp到monitor的/masterha/app1目录下。
 
Sun May
21 20:50:51 2017 - [info] * Phase 3.2: Saving Dead Master's Binlog Phase..
Sun May 21 20:50:51 2017 - [info]
Sun May
21 20:50:52 2017 - [info] Fetching dead master's binary logs..
Sun May 21 20:50:52 2017 - [info] Executing command on the dead master 192.168.244.10(192.168.244.10:3306): save_binary_logs --command=save --start_file=mysql-bin.000001  --start_pos=880 --binlog_dir=/var/lib/mysql --output_file=/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56
  Creating
/tmp if not exists..    ok.
Concat binary
/relay logs from mysql-bin.000001 pos 880 to mysql-bin.000001 EOF into /tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog ..
Binlog Checksum enabled
  Dumping binlog format description event, from position
0 to 120.. ok.
  Dumping effective binlog data from
/var/lib/mysql/mysql-bin.000001 position 880 to tail(1308).. ok.
Binlog Checksum enabled
Concat succeeded.
Sun May
21 20:50:52 2017 - [info] scp from root@192.168.244.10:/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog to local:/masterha/app1/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog succeeded.
Sun May
21 20:50:52 2017 - [info] HealthCheck: SSH to 192.168.244.20 is reachable.
Sun May
21 20:50:53 2017 - [info] HealthCheck: SSH to 192.168.244.30 is reachable.
Sun May
21 20:50:53 2017 - [info]

-- 3.3 选新主阶段
      首先判断最新的slave中是否包括最旧的二进制日志(mysql
-bin.000001:452)以后的relay log。
      接着选新主,
      因为192.
168.244.20中设置了candidate_master设置了,所以192.168.244.20被指定为新主。
 

Sun May
21 20:50:53 2017 - [info] * Phase 3.3: Determining New Master Phase..
Sun May
21 20:50:53 2017 - [info]
Sun May
21 20:50:53 2017 - [info] Finding the latest slave that has all relay logs for recovering other slaves..
Sun May
21 20:50:53 2017 - [info] Checking whether 192.168.244.30 has relay logs from the oldest position..
Sun May
21 20:50:53 2017 - [info] Executing command: apply_diff_relay_logs --command=find --latest_mlf=mysql-bin.000001 --latest_rmlp=880 --target_mlf=mysql-bin.000001 --target_rmlp=452 --server_id=3 --workdir=/tmp --timestamp=20170521205050 --manager_version=0.56 --relay_log_info=/var/lib/mysql/relay-log.info  --relay_dir=/var/lib/mysql/  :
    Opening
/var/lib/mysql/relay-log.info ... ok.
    Relay log found at
/var/lib/mysql, up to mysqld-relay-bin.000003
Fast relay log position search failed. Reading relay logs to
find..
Reading mysqld
-relay-bin.000003
Binlog Checksum enabled
Reading mysqld
-relay-bin.000002
Binlog Checksum enabled
Master Version is
5.6.31-log
Binlog Checksum enabled
mysqld
-relay-bin.000002 contains master mysql-bin.000001 from position 120
Target relay log FOUND
!
Sun May
21 20:50:53 2017 - [info] OK. 192.168.244.30 has all relay logs.
Sun May
21 20:50:53 2017 - [info] Searching new master from slaves..
Sun May
21 20:50:53 2017 - [info]  Candidate masters from the configuration file:
Sun May
21 20:50:53 2017 - [info192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May
21 20:50:53 2017 - [info]    Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May
21 20:50:53 2017 - [info]    Primary candidate for the new Master (candidate_master is set)
Sun May
21 20:50:53 2017 - [info]  Non-candidate masters:
Sun May
21 20:50:53 2017 - [info]  Searching from candidate_master slaves which have received the latest relay log events..
Sun May
21 20:50:53 2017 - [info]  Not found.
Sun May
21 20:50:53 2017 - [info]  Searching from all candidate_master slaves..
Sun May
21 20:50:53 2017 - [info] New master is 192.168.244.20(192.168.244.20:3306)
Sun May
21 20:50:53 2017 - [info] Starting master failover..
Sun May
21 20:50:53 2017 - [info]
From:
192.168.244.10(192.168.244.10:3306) (current master)
+--192.168.244.20(192.168.244.20:3306)
+--192.168.244.30(192.168.244.30:3306)

To:
192.168.244.20(192.168.244.20:3306) (new master)
+--192.168.244.30(192.168.244.30:3306)
Sun May
21 20:50:53 2017 - [info]

-- 3.3 获取新主所需的差异二进制日志,包括两部分
     
1> 新主和最新的slave之间差异的relay log
     
2> 保存在MHA Manager上的最新的slave和原master之前差异的binlog
      其中,差异的relay log通过如下方式获取:
      ssh到192.
168.244.30上,执行apply_diff_relay_logs获取差异的relay log。将差异的relay log scp到192.168.244.20

Sun May
21 20:50:53 2017 - [info] * Phase 3.3: New Master Diff Log Generation Phase..
Sun May
21 20:50:53 2017 - [info]
Sun May
21 20:50:53 2017 - [info] Server 192.168.244.20 received relay logs up to: mysql-bin.000001:452
Sun May
21 20:50:53 2017 - [info] Need to get diffs from the latest slave(192.168.244.30) up to: mysql-bin.000001:880 (using the latest slave's relay logs)
Sun May 21 20:50:53 2017 - [info] Connecting to the latest slave host 192.168.244.30, generating diff relay log files..
Sun May
21 20:50:53 2017 - [info] Executing command: apply_diff_relay_logs --command=generate_and_send --scp_user=root --scp_host=192.168.244.20 --latest_mlf=mysql-bin.000001 --latest_rmlp=880 --target_mlf=mysql-bin.000001 --target_rmlp=452 --server_id=3 --diff_file_readtolatest=/tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog --workdir=/tmp --timestamp=20170521205050 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --relay_log_info=/var/lib/mysql/relay-log.info  --relay_dir=/var/lib/mysql/
Sun May
21 20:50:54 2017 - [info]
    Opening
/var/lib/mysql/relay-log.info ... ok.
    Relay log found at
/var/lib/mysql, up to mysqld-relay-bin.000003
Fast relay log position search failed. Reading relay logs to
find..
Reading mysqld
-relay-bin.000003
Binlog Checksum enabled
Reading mysqld
-relay-bin.000002
Binlog Checksum enabled
Master Version is
5.6.31-log
Binlog Checksum enabled
mysqld
-relay-bin.000002 contains master mysql-bin.000001 from position 120
Target relay log
file/position found. start_file:mysqld-relay-bin.000002, start_pos:615.
Concat binary
/relay logs from mysqld-relay-bin.000002 pos 615 to mysqld-relay-bin.000003 EOF into /tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog ..
Binlog Checksum enabled
Binlog Checksum enabled
  Dumping binlog format description event, from position
0 to 283.. ok.
  Dumping effective binlog data from
/var/lib/mysql/mysqld-relay-bin.000002 position 615 to tail(1066).. ok.
  Dumping binlog
head events (rotate events), skipping format description events from /var/lib/mysql/mysqld-relay-bin.000003..  Binlog Checksum enabled
dumped up to pos
120. ok.
  No need to dump effective binlog data from
/var/lib/mysql/mysqld-relay-bin.000003 (pos starts 120, filesize 120). Skipping.
Binlog Checksum enabled
Binlog Checksum enabled
Concat succeeded.
Generating
diff relay log succeeded. Saved at /tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog .
scp node3:/tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog to root@192.168.244.20(22) succeeded.
Sun May
21 20:50:54 2017 - [info]  Generating diff files succeeded.
Sun May
21 20:50:54 2017 - [info] Sending binlog..
Sun May
21 20:50:54 2017 - [info] scp from local:/masterha/app1/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog to root@192.168.244.20:/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog succeeded.
Sun May
21 20:50:54 2017 - [info]

-- 3.4 应用从master保存的二进制日志事件
      首先,等原来的所有的relay log都应用完。
      其次,再通过apply_diff_relay_logs应用差异的relay log,及差异的binlog。
            应用完毕后,得到新的master binlog的文件和位置,其它slave可根据该文件和位置来建立主从复制关系。
      第三,执行master_ip_failover脚本,执行如下操作
           
1> 将新主的read_only设置为0
           
2> 启动vip
           
Sun May
21 20:50:54 2017 - [info] * Phase 3.4: Master Log Apply Phase..
Sun May
21 20:50:54 2017 - [info]
Sun May
21 20:50:54 2017 - [info] *NOTICE: If any error happens from this phase, manual recovery is needed.
Sun May
21 20:50:54 2017 - [info] Starting recovery on 192.168.244.20(192.168.244.20:3306)..
Sun May
21 20:50:54 2017 - [info]  Generating diffs succeeded.
Sun May
21 20:50:54 2017 - [info] Waiting until all relay logs are applied.
Sun May
21 20:50:54 2017 - [infodone.
Sun May
21 20:50:54 2017 - [info] Getting slave status..
Sun May
21 20:50:54 2017 - [info] This slave(192.168.244.20)'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000001:452). No need to recover from Exec_Master_Log_Pos.
Sun May 21 20:50:54 2017 - [info] Connecting to the target slave host 192.168.244.20, running recover script..
Sun May
21 20:50:54 2017 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user='monitor' --slave_host=192.168.244.20 --slave_ip=192.168.244.20  --slave_port=3306 --apply_files=/tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog,/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog --workdir=/tmp --target_version=5.6.31-log --timestamp=20170521205050 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --slave_pass=xxx
Sun May
21 20:50:55 2017 - [info]
Concat all apply files to
/tmp/total_binlog_for_192.168.244.20_3306.20170521205050.binlog ..
Copying the first binlog
file /tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog to /tmp/total_binlog_for_192.168.244.20_3306.20170521205050.binlog.. ok.
  Dumping binlog
head events (rotate events), skipping format description events from /tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog..  Binlog Checksum enabled
dumped up to pos
120. ok.
/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog has effective binlog events from pos 120.
  Dumping effective binlog data from
/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog position 120 to tail(548).. ok.
Concat succeeded.
All apply target binary logs are concatinated at
/tmp/total_binlog_for_192.168.244.20_3306.20170521205050.binlog .
MySQL client version is
5.6.31. Using --binary-mode.
Applying differential binary
/relay log files /tmp/relay_from_read_to_latest_192.168.244.20_3306_20170521205050.binlog,/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog on 192.168.244.20:3306. This may take long time...
Applying log files succeeded.
Sun May
21 20:50:55 2017 - [info]  All relay logs were successfully applied.
Sun May
21 20:50:55 2017 - [info] Getting new master's binlog name and position..
Sun May 21 20:50:55 2017 - [info]  mysql-bin.000002:976
Sun May
21 20:50:55 2017 - [info]  All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='192.168.244.20', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000002', MASTER_LOG_POS=976, MASTER_USER='repl', MASTER_PASSWORD='xxx';
Sun May
21 20:50:55 2017 - [info] Executing master IP activate script:
Sun May
21 20:50:55 2017 - [info]  /usr/local/bin/master_ip_failover --command=start --ssh_user=root --orig_master_host=192.168.244.10 --orig_master_ip=192.168.244.10 --orig_master_port=3306 --new_master_host=192.168.244.20 --new_master_ip=192.168.244.20 --new_master_port=3306 --new_master_user='monitor' --new_master_password='monitor123' 
Set read_only
=0 on the new master.
Enabling the VIP
192.168.244.188 on the new master: 192.168.244.20
Sun May
21 20:50:55 2017 - [info]  OK.
Sun May
21 20:50:55 2017 - [info] ** Finished master recovery successfully.
Sun May
21 20:50:55 2017 - [info] * Phase 3: Master Recovery Phase completed.

-- 第四阶段 slave恢复阶段
-- 4.1 因为192.168.244.30拥有最新的relay log,所以也没必要获取差异的relay log
-- 4.2 开始slave的恢复阶段
     
1> 将monitor上保存的master上的差异的二进制日志scp到slave上。
     
2> 应用差异日志。
     
3> 清除原来的复制关系,并再次执行change master命令建立新的主从同步。
    如果有多个slave,则该恢复过程是并行的。
   
Sun May
21 20:50:55 2017 - [info]
Sun May
21 20:50:55 2017 - [info] * Phase 4: Slaves Recovery Phase..
Sun May
21 20:50:55 2017 - [info]
Sun May
21 20:50:55 2017 - [info] * Phase 4.1: Starting Parallel Slave Diff Log Generation Phase..
Sun May
21 20:50:55 2017 - [info]
Sun May
21 20:50:55 2017 - [info] -- Slave diff file generation on host 192.168.244.30(192.168.244.30:3306) started, pid: 4966. Check tmp log /masterha/app1/192.168.244.30_3306_20170521205050.log if it takes time..
Sun May
21 20:50:56 2017 - [info]
Sun May
21 20:50:56 2017 - [info] Log messages from 192.168.244.30 ...
Sun May
21 20:50:56 2017 - [info]
Sun May
21 20:50:55 2017 - [info]  This server has all relay logs. No need to generate diff files from the latest slave.
Sun May
21 20:50:56 2017 - [info] End of log messages from 192.168.244.30.
Sun May
21 20:50:56 2017 - [info] -- 192.168.244.30(192.168.244.30:3306) has the latest relay log events.
Sun May
21 20:50:56 2017 - [info] Generating relay diff files from the latest slave succeeded.
Sun May
21 20:50:56 2017 - [info]
Sun May
21 20:50:56 2017 - [info] * Phase 4.2: Starting Parallel Slave Log Apply Phase..
Sun May
21 20:50:56 2017 - [info]
Sun May
21 20:50:56 2017 - [info] -- Slave recovery on host 192.168.244.30(192.168.244.30:3306) started, pid: 4968. Check tmp log /masterha/app1/192.168.244.30_3306_20170521205050.log if it takes time..
Sun May
21 20:50:58 2017 - [info]
Sun May
21 20:50:58 2017 - [info] Log messages from 192.168.244.30 ...
Sun May
21 20:50:58 2017 - [info]
Sun May
21 20:50:56 2017 - [info] Sending binlog..
Sun May
21 20:50:57 2017 - [info] scp from local:/masterha/app1/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog to root@192.168.244.30:/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog succeeded.
Sun May
21 20:50:57 2017 - [info] Starting recovery on 192.168.244.30(192.168.244.30:3306)..
Sun May
21 20:50:57 2017 - [info]  Generating diffs succeeded.
Sun May
21 20:50:57 2017 - [info] Waiting until all relay logs are applied.
Sun May
21 20:50:57 2017 - [infodone.
Sun May
21 20:50:57 2017 - [info] Getting slave status..
Sun May
21 20:50:57 2017 - [info] This slave(192.168.244.30)'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000001:880). No need to recover from Exec_Master_Log_Pos.
Sun May 21 20:50:57 2017 - [info] Connecting to the target slave host 192.168.244.30, running recover script..
Sun May
21 20:50:57 2017 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user='monitor' --slave_host=192.168.244.30 --slave_ip=192.168.244.30  --slave_port=3306 --apply_files=/tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog --workdir=/tmp --target_version=5.6.31-log --timestamp=20170521205050 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --slave_pass=xxx
Sun May
21 20:50:57 2017 - [info]
MySQL client version is
5.6.31. Using --binary-mode.
Applying differential binary
/relay log files /tmp/saved_master_binlog_from_192.168.244.10_3306_20170521205050.binlog on 192.168.244.30:3306. This may take long time...
Applying log files succeeded.
Sun May
21 20:50:57 2017 - [info]  All relay logs were successfully applied.
Sun May
21 20:50:57 2017 - [info]  Resetting slave 192.168.244.30(192.168.244.30:3306) and starting replication from the new master 192.168.244.20(192.168.244.20:3306)..
Sun May
21 20:50:58 2017 - [info]  Executed CHANGE MASTER.
Sun May
21 20:50:58 2017 - [info]  Slave started.
Sun May
21 20:50:58 2017 - [info] End of log messages from 192.168.244.30.
Sun May
21 20:50:58 2017 - [info] -- Slave recovery on host 192.168.244.30(192.168.244.30:3306) succeeded.
Sun May
21 20:50:58 2017 - [info] All new slave servers recovered successfully.

-- 第五阶段 清理阶段
  从MHA的配置文件中剔除server1的配置信息
 
Sun May
21 20:50:58 2017 - [info]
Sun May
21 20:50:58 2017 - [info] * Phase 5: New master cleanup phase..
Sun May
21 20:50:58 2017 - [info]
Sun May
21 20:50:58 2017 - [info] Resetting slave info on the new master..
Sun May
21 20:50:58 2017 - [info192.168.244.20: Resetting slave info succeeded.
Sun May
21 20:50:58 2017 - [info] Master failover to 192.168.244.20(192.168.244.20:3306) completed successfully.
Sun May
21 20:50:58 2017 - [info] Deleted server1 entry from /etc/masterha/app1.cnf .
Sun May
21 20:50:58 2017 - [info]

-- 生成 Failover 报告,发送告警邮件

----- Failover Report -----

app1: MySQL Master failover
192.168.244.10(192.168.244.10:3306) to 192.168.244.20(192.168.244.20:3306) succeeded

Master
192.168.244.10(192.168.244.10:3306) is down!

Check MHA Manager logs at node4:
/masterha/app1/manager.log for details.

Started automated(non
-interactive) failover.
Invalidated master IP address on
192.168.244.10(192.168.244.10:3306)
The latest slave
192.168.244.30(192.168.244.30:3306) has all relay logs for recovery.
Selected
192.168.244.20(192.168.244.20:3306) as a new master.
192.168.244.20(192.168.244.20:3306): OK: Applying all logs succeeded.
192.168.244.20(192.168.244.20:3306): OK: Activated master IP address.
192.168.244.30(192.168.244.30:3306): This host has the latest relay log events.
Generating relay
diff files from the latest slave succeeded.
192.168.244.30(192.168.244.30:3306): OK: Applying all logs succeeded. Slave started, replicating from 192.168.244.20(192.168.244.20:3306)
192.168.244.20(192.168.244.20:3306): Resetting slave info succeeded.
Master failover to
192.168.244.20(192.168.244.20:3306) completed successfully.
Sun May
21 20:50:58 2017 - [info] Sending mail..
Unknown option: conf
 

从上面的日志输出可以看出整个MHA的切换过程

首先,MHA Manager检测到master不可用,则会通过另外两个slave检查master的可用性。一共检测4次。

     同时判断MHA Manager到master的ssh可用性。

     ssh可用性的判断结果影响后后续切换中的“Phase 3.2: Saving Dead Master's Binlog Phase”

Phase 1: Configuration Check Phase..

     检查了MHA的配置信息,并再次判断了master的可用性。

Phase 2: Dead Master Shutdown Phase..

     宕��的master处理阶段,包括摘除VIP,执行shutdown_script中定义的脚本。

Phase 3: Master Recovery Phase..

  Phase 3.1: Getting Latest Slaves Phase..

   判断哪个slave拥有最新的relay log(通过比较show slave status中的Master_Log_File, Read_Master_Log_Pos位置),

   哪个slave拥有最旧的relay log

   Phase 3.2: Saving Dead Master's Binlog Phase..

   根据上面得到的slave的最新位置信息,将差异的二进制日志保存到MHA Manager的指定目录下。

   如果在第一步骤中,判断了MHA Manager到master的ssh不可用,则会跳过这个阶段。

   Phase 3.3: Determining New Master Phase..

   选择新的master

     

   Phase 3.3: New Master Diff Log Generation Phase..

   将差异的relay log和master差异日志scp到新的master上。

   

   Phase 3.4: Master Log Apply Phase..

   首先,等待slave上已有的relay log都应用完。

   其次,通过apply_diff_relay_logs应用差异的relay log,及差异的binlog。

   应用完毕后,得到新的master binlog的文件和位置,其它slave可根据该文件和位置来建立主从复制关系。

   第三,执行master_ip_failover脚本,执行如下操作

   1> 将新主的read_only设置为0

   2> 启动vip

   

Phase 4: Slaves Recovery Phase

   Phase 4.1: Starting Parallel Slave Diff Log Generation Phase

   为slave获取差异的relay log

   因为192.168.244.30拥有最新的relay log,所以也没必要获取差异的relay log

   Phase 4.2: Starting Parallel Slave Log Apply Phase

   开始slave的恢复阶段

   1> 将差异的relay log和master差异日志scp到slave上。

   2> 应用差异日志。

   3> 清除原来的复制关系,并再次执行change master命令建立新的主从同步。

   如果有多个slave,则该恢复过程是并行的。

     

Phase 5: New master cleanup phase

    从MHA的配置文件中剔除server1的配置信息

最后,生成Failover Report并发送告警邮件。

 

更多详情见请继续阅读下一页的精彩内容http://www.linuxidc.com/Linux/2017-05/144249p2.htm

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