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

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，可参考另外一篇博客：

MySQL高可用方案MHA的部署和原理

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

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

[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*/;

View Code

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 - [info]   192.168.244.10(192.168.244.10:3306)
Sun May 21 20:50:50 2017 - [info] Alive Servers:
Sun May 21 20:50:50 2017 - [info]   192.168.244.20(192.168.244.20:3306)
Sun May 21 20:50:50 2017 - [info]   192.168.244.30(192.168.244.30:3306)
Sun May 21 20:50:50 2017 - [info] Alive Slaves:
Sun May 21 20:50:50 2017 - [info]   192.168.244.20(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 - [info]   192.168.244.30(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 - [info]   192.168.244.10(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 - [info]   192.168.244.20(192.168.244.20:3306)
Sun May 21 20:50:51 2017 - [info]   192.168.244.30(192.168.244.30:3306)
Sun May 21 20:50:51 2017 - [info] Alive Slaves:
Sun May 21 20:50:51 2017 - [info]   192.168.244.20(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]   192.168.244.30(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 - [info]   done.
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 - [info]   done.
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 - [info]  done.
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 - [info]   192.168.244.30(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 - [info]   192.168.244.20(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 - [info]   192.168.244.20(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 - [info]  done.
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 - [info]  done.
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 - [info]  192.168.244.20: 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..

宕机的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。

手动Failover

与自动Failover相对应的是手动Failover，即当master发生故障时，通过手动执行脚本来进行故障切换。

命令如下：

# masterha_master_switch --master_state=dead --conf=/etc/masterha/app1.cnf --dead_master_host=192.168.244.10 --dead_master_port=3306 --new_master_host=192.168.244.30 --new_master_port=3306 --ignore_last_failover

输出日志信息如下：

--dead_master_ip=<dead_master_ip> is not set. Using 192.168.244.10.
Wed May 24 19:44:20 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Wed May 24 19:44:20 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Wed May 24 19:44:20 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Wed May 24 19:44:20 2017 - [info] MHA::MasterFailover version 0.56.
Wed May 24 19:44:20 2017 - [info] Starting master failover.
Wed May 24 19:44:20 2017 - [info] 
Wed May 24 19:44:20 2017 - [info] * Phase 1: Configuration Check Phase..
Wed May 24 19:44:20 2017 - [info] 
Wed May 24 19:44:21 2017 - [info] GTID failover mode = 0
Wed May 24 19:44:21 2017 - [info] Dead Servers:
Wed May 24 19:44:21 2017 - [info]   192.168.244.10(192.168.244.10:3306)
Wed May 24 19:44:21 2017 - [info] Checking master reachability via MySQL(double check)...
Wed May 24 19:44:21 2017 - [info]  ok.
Wed May 24 19:44:21 2017 - [info] Alive Servers:
Wed May 24 19:44:21 2017 - [info]   192.168.244.20(192.168.244.20:3306)
Wed May 24 19:44:21 2017 - [info]   192.168.244.30(192.168.244.30:3306)
Wed May 24 19:44:21 2017 - [info] Alive Slaves:
Wed May 24 19:44:21 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:44:21 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Wed May 24 19:44:21 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Wed May 24 19:44:21 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:44:21 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Master 192.168.244.10(192.168.244.10:3306) is dead. Proceed? (yes/NO): yes
Wed May 24 19:44:23 2017 - [info] Starting Non-GTID based failover.
Wed May 24 19:44:23 2017 - [info] 
Wed May 24 19:44:23 2017 - [info] ** Phase 1: Configuration Check Phase completed.
Wed May 24 19:44:23 2017 - [info] 
Wed May 24 19:44:23 2017 - [info] * Phase 2: Dead Master Shutdown Phase..
Wed May 24 19:44:23 2017 - [info] 
Wed May 24 19:44:24 2017 - [info] HealthCheck: SSH to 192.168.244.10 is reachable.
Wed May 24 19:44:24 2017 - [info] Forcing shutdown so that applications never connect to the current master..
Wed May 24 19:44:24 2017 - [info] Executing master IP deactivation script:
Wed May 24 19:44:24 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
Wed May 24 19:44:24 2017 - [info]  done.
Wed May 24 19:44:24 2017 - [warning] shutdown_script is not set. Skipping explicit shutting down of the dead master.
Wed May 24 19:44:24 2017 - [info] * Phase 2: Dead Master Shutdown Phase completed.
Wed May 24 19:44:24 2017 - [info] 
Wed May 24 19:44:24 2017 - [info] * Phase 3: Master Recovery Phase..
Wed May 24 19:44:24 2017 - [info] 
Wed May 24 19:44:24 2017 - [info] * Phase 3.1: Getting Latest Slaves Phase..
Wed May 24 19:44:24 2017 - [info] 
Wed May 24 19:44:24 2017 - [info] The latest binary log file/position on all slaves is mysql-bin.000002:120
Wed May 24 19:44:24 2017 - [info] Latest slaves (Slaves that received relay log files to the latest):
Wed May 24 19:44:24 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:44:24 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Wed May 24 19:44:24 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Wed May 24 19:44:24 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:44:24 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Wed May 24 19:44:24 2017 - [info] The oldest binary log file/position on all slaves is mysql-bin.000002:120
Wed May 24 19:44:24 2017 - [info] Oldest slaves:
Wed May 24 19:44:24 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:44:24 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Wed May 24 19:44:24 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Wed May 24 19:44:24 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:44:24 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Wed May 24 19:44:24 2017 - [info] 
Wed May 24 19:44:24 2017 - [info] * Phase 3.2: Saving Dead Master's Binlog Phase..
Wed May 24 19:44:24 2017 - [info] 
Wed May 24 19:44:24 2017 - [info] Fetching dead master's binary logs..
Wed May 24 19:44:24 2017 - [info] Executing command on the dead master 192.168.244.10(192.168.244.10:3306): save_binary_logs --comman
d=save --start_file=mysql-bin.000002  --start_pos=120 --binlog_dir=/var/lib/mysql --output_file=/tmp/saved_master_binlog_from_192.168.244.10_3306_20170524194420.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.000002 pos 120 to mysql-bin.000002 EOF into /tmp/saved_master_binlog_from_192.168.244.10_330
6_20170524194420.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.000002 position 120 to tail(143).. ok.
 Binlog Checksum enabled
 Concat succeeded.
saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog                                 100%  143     0.1KB/s   00:00    
Wed May 24 19:44:24 2017 - [info] scp from root@192.168.244.10:/tmp/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlo
g to local:/masterha/app1/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog succeeded.Wed May 24 19:44:25 2017 - [info] HealthCheck: SSH to 192.168.244.20 is reachable.
Wed May 24 19:44:25 2017 - [info] HealthCheck: SSH to 192.168.244.30 is reachable.
Wed May 24 19:44:25 2017 - [info] 
Wed May 24 19:44:25 2017 - [info] * Phase 3.3: Determining New Master Phase..
Wed May 24 19:44:25 2017 - [info] 
Wed May 24 19:44:25 2017 - [info] Finding the latest slave that has all relay logs for recovering other slaves..
Wed May 24 19:44:25 2017 - [info] All slaves received relay logs to the same position. No need to resync each other.
Wed May 24 19:44:25 2017 - [info] 192.168.244.30 can be new master.
Wed May 24 19:44:25 2017 - [info] New master is 192.168.244.30(192.168.244.30:3306)
Wed May 24 19:44:25 2017 - [info] Starting master failover..
Wed May 24 19:44:25 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:
192.168.244.30(192.168.244.30:3306) (new master)
+--192.168.244.20(192.168.244.20:3306)

Starting master switch from 192.168.244.10(192.168.244.10:3306) to 192.168.244.30(192.168.244.30:3306)? (yes/NO): yes
Wed May 24 19:44:32 2017 - [info] New master decided manually is 192.168.244.30(192.168.244.30:3306)
Wed May 24 19:44:32 2017 - [info] 
Wed May 24 19:44:32 2017 - [info] * Phase 3.3: New Master Diff Log Generation Phase..
Wed May 24 19:44:32 2017 - [info] 
Wed May 24 19:44:32 2017 - [info]  This server has all relay logs. No need to generate diff files from the latest slave.
Wed May 24 19:44:32 2017 - [info] Sending binlog..
saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog                                 100%  143     0.1KB/s   00:00    
Wed May 24 19:44:33 2017 - [info] scp from local:/masterha/app1/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog to
 root@192.168.244.30:/tmp/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog succeeded.Wed May 24 19:44:33 2017 - [info] 
Wed May 24 19:44:33 2017 - [info] * Phase 3.4: Master Log Apply Phase..
Wed May 24 19:44:33 2017 - [info] 
Wed May 24 19:44:33 2017 - [info] *NOTICE: If any error happens from this phase, manual recovery is needed.
Wed May 24 19:44:33 2017 - [info] Starting recovery on 192.168.244.30(192.168.244.30:3306)..
Wed May 24 19:44:33 2017 - [info]  Generating diffs succeeded.
Wed May 24 19:44:33 2017 - [info] Waiting until all relay logs are applied.
Wed May 24 19:44:33 2017 - [info]  done.
Wed May 24 19:44:33 2017 - [info] Getting slave status..
Wed May 24 19:44:33 2017 - [info] This slave(192.168.244.30)'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000002:120
). No need to recover from Exec_Master_Log_Pos.Wed May 24 19:44:33 2017 - [info] Connecting to the target slave host 192.168.244.30, running recover script..
Wed May 24 19:44:33 2017 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user='monitor' --slave_host=192.16
8.244.30 --slave_ip=192.168.244.30  --slave_port=3306 --apply_files=/tmp/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog --workdir=/tmp --target_version=5.6.31-log --timestamp=20170524194420 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --slave_pass=xxxWed May 24 19:44:33 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_20170524194420.binlog on 192.168.244.3
0:3306. This may take long time...Applying log files succeeded.
Wed May 24 19:44:33 2017 - [info]  All relay logs were successfully applied.
Wed May 24 19:44:33 2017 - [info] Getting new master's binlog name and position..
Wed May 24 19:44:33 2017 - [info]  mysql-bin.000001:1429
Wed May 24 19:44:33 2017 - [info]  All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_
HOST='192.168.244.30', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=1429, MASTER_USER='repl', MASTER_PASSWORD='xxx';Wed May 24 19:44:33 2017 - [info] Executing master IP activate script:
Wed May 24 19:44:33 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=192.168.244.30 --new_master_ip=192.168.244.30 --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: 192.168.244.30 
Wed May 24 19:44:33 2017 - [info]  OK.
Wed May 24 19:44:33 2017 - [info] ** Finished master recovery successfully.
Wed May 24 19:44:33 2017 - [info] * Phase 3: Master Recovery Phase completed.
Wed May 24 19:44:33 2017 - [info] 
Wed May 24 19:44:33 2017 - [info] * Phase 4: Slaves Recovery Phase..
Wed May 24 19:44:33 2017 - [info] 
Wed May 24 19:44:33 2017 - [info] * Phase 4.1: Starting Parallel Slave Diff Log Generation Phase..
Wed May 24 19:44:33 2017 - [info] 
Wed May 24 19:44:33 2017 - [info] -- Slave diff file generation on host 192.168.244.20(192.168.244.20:3306) started, pid: 1598. Check
 tmp log /masterha/app1/192.168.244.20_3306_20170524194420.log if it takes time..Wed May 24 19:44:34 2017 - [info] 
Wed May 24 19:44:34 2017 - [info] Log messages from 192.168.244.20 ...
Wed May 24 19:44:34 2017 - [info] 
Wed May 24 19:44:33 2017 - [info]  This server has all relay logs. No need to generate diff files from the latest slave.
Wed May 24 19:44:34 2017 - [info] End of log messages from 192.168.244.20.
Wed May 24 19:44:34 2017 - [info] -- 192.168.244.20(192.168.244.20:3306) has the latest relay log events.
Wed May 24 19:44:34 2017 - [info] Generating relay diff files from the latest slave succeeded.
Wed May 24 19:44:34 2017 - [info] 
Wed May 24 19:44:34 2017 - [info] * Phase 4.2: Starting Parallel Slave Log Apply Phase..
Wed May 24 19:44:34 2017 - [info] 
Wed May 24 19:44:34 2017 - [info] -- Slave recovery on host 192.168.244.20(192.168.244.20:3306) started, pid: 1600. Check tmp log /ma
sterha/app1/192.168.244.20_3306_20170524194420.log if it takes time..saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog                                 100%  143     0.1KB/s   00:00    
Wed May 24 19:44:35 2017 - [info] 
Wed May 24 19:44:35 2017 - [info] Log messages from 192.168.244.20 ...
Wed May 24 19:44:35 2017 - [info] 
Wed May 24 19:44:34 2017 - [info] Sending binlog..
Wed May 24 19:44:35 2017 - [info] scp from local:/masterha/app1/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog to
 root@192.168.244.20:/tmp/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog succeeded.Wed May 24 19:44:35 2017 - [info] Starting recovery on 192.168.244.20(192.168.244.20:3306)..
Wed May 24 19:44:35 2017 - [info]  Generating diffs succeeded.
Wed May 24 19:44:35 2017 - [info] Waiting until all relay logs are applied.
Wed May 24 19:44:35 2017 - [info]  done.
Wed May 24 19:44:35 2017 - [info] Getting slave status..
Wed May 24 19:44:35 2017 - [info] This slave(192.168.244.20)'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000002:120
). No need to recover from Exec_Master_Log_Pos.Wed May 24 19:44:35 2017 - [info] Connecting to the target slave host 192.168.244.20, running recover script..
Wed May 24 19:44:35 2017 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user='monitor' --slave_host=192.16
8.244.20 --slave_ip=192.168.244.20  --slave_port=3306 --apply_files=/tmp/saved_master_binlog_from_192.168.244.10_3306_20170524194420.binlog --workdir=/tmp --target_version=5.6.31-log --timestamp=20170524194420 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --slave_pass=xxxWed May 24 19:44:35 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_20170524194420.binlog on 192.168.244.2
0:3306. This may take long time...Applying log files succeeded.
Wed May 24 19:44:35 2017 - [info]  All relay logs were successfully applied.
Wed May 24 19:44:35 2017 - [info]  Resetting slave 192.168.244.20(192.168.244.20:3306) and starting replication from the new master 1
92.168.244.30(192.168.244.30:3306)..Wed May 24 19:44:35 2017 - [info]  Executed CHANGE MASTER.
Wed May 24 19:44:35 2017 - [info]  Slave started.
Wed May 24 19:44:35 2017 - [info] End of log messages from 192.168.244.20.
Wed May 24 19:44:35 2017 - [info] -- Slave recovery on host 192.168.244.20(192.168.244.20:3306) succeeded.
Wed May 24 19:44:35 2017 - [info] All new slave servers recovered successfully.
Wed May 24 19:44:35 2017 - [info] 
Wed May 24 19:44:35 2017 - [info] * Phase 5: New master cleanup phase..
Wed May 24 19:44:35 2017 - [info] 
Wed May 24 19:44:35 2017 - [info] Resetting slave info on the new master..
Wed May 24 19:44:35 2017 - [info]  192.168.244.30: Resetting slave info succeeded.
Wed May 24 19:44:35 2017 - [info] Master failover to 192.168.244.30(192.168.244.30:3306) completed successfully.
Wed May 24 19:44:35 2017 - [info] 

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

app1: MySQL Master failover 192.168.244.10(192.168.244.10:3306) to 192.168.244.30(192.168.244.30:3306) succeeded

Master 192.168.244.10(192.168.244.10:3306) is down!

Check MHA Manager logs at node4 for details.

Started manual(interactive) failover.
Invalidated master IP address on 192.168.244.10(192.168.244.10:3306)
The latest slave 192.168.244.20(192.168.244.20:3306) has all relay logs for recovery.
Selected 192.168.244.30(192.168.244.30:3306) as a new master.
192.168.244.30(192.168.244.30:3306): OK: Applying all logs succeeded.
192.168.244.30(192.168.244.30:3306): OK: Activated master IP address.
192.168.244.20(192.168.244.20:3306): This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
192.168.244.20(192.168.244.20:3306): OK: Applying all logs succeeded. Slave started, replicating from 192.168.244.30(192.168.244.30:3
306)192.168.244.30(192.168.244.30:3306): Resetting slave info succeeded.
Master failover to 192.168.244.30(192.168.244.30:3306) completed successfully.
Wed May 24 19:44:35 2017 - [info] Sending mail..
Unknown option: conf

在切换的过程中，会有两次确认操作。

通过日志的输出，可以看出，手动Failover的切换逻辑和自动Failover的切换逻辑基本一致。

在上面的命令中，显示指定了--new_master_host参数，如果，没有显示指定该参数的话，则默认新主为192.168.244.20，因为在/etc/masterha/app1.cnf中将主机设置为candidate_master=1。

事实上，如果master alive的话，是不允许切换的。

Wed May 24 19:26:24 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Wed May 24 19:26:24 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Wed May 24 19:26:24 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Wed May 24 19:26:24 2017 - [info] MHA::MasterFailover version 0.56.
Wed May 24 19:26:24 2017 - [info] Starting master failover.
Wed May 24 19:26:24 2017 - [info] 
Wed May 24 19:26:24 2017 - [info] * Phase 1: Configuration Check Phase..
Wed May 24 19:26:24 2017 - [info] 
Wed May 24 19:26:26 2017 - [info] GTID failover mode = 0
Wed May 24 19:26:26 2017 - [info] Dead Servers:
Wed May 24 19:26:26 2017 - [error][/usr/local/share/perl5/MHA/MasterFailover.pm, ln187] None of server is dead. Stop failover.
Wed May 24 19:26:26 2017 - [error][/usr/local/share/perl5/MHA/ManagerUtil.pm, ln177] Got ERROR:  at /usr/local/bin/masterha_master_switch line 53.

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在默认情况下，如果MHA检测到两次切换的时间小于8小时，则不允许进行Failover，这个时候，需指定--ignore_last_failover参数

# masterha_master_switch --master_state=dead --conf=/etc/masterha/app1.cnf --dead_master_host=192.168.244.10 --dead_master_port=3306
--dead_master_ip=<dead_master_ip> is not set. Using 192.168.244.10.
Wed May 24 19:26:24 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Wed May 24 19:26:24 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Wed May 24 19:26:24 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Wed May 24 19:26:24 2017 - [info] MHA::MasterFailover version 0.56.
Wed May 24 19:26:24 2017 - [info] Starting master failover.
Wed May 24 19:26:24 2017 - [info] 
Wed May 24 19:26:24 2017 - [info] * Phase 1: Configuration Check Phase..
Wed May 24 19:26:24 2017 - [info] 
Wed May 24 19:26:26 2017 - [info] GTID failover mode = 0
Wed May 24 19:26:26 2017 - [info] Dead Servers:
Wed May 24 19:26:26 2017 - [error][/usr/local/share/perl5/MHA/MasterFailover.pm, ln187] None of server is dead. Stop failover.
Wed May 24 19:26:26 2017 - [error][/usr/local/share/perl5/MHA/ManagerUtil.pm, ln177] Got ERROR:  at /usr/local/bin/masterha_master_sw
itch line 53.[root@node4 ~]# masterha_master_switch --master_state=dead --conf=/etc/masterha/app1.cnf --dead_master_host=192.168.244.10 --dead_mas
ter_port=3306--dead_master_ip=<dead_master_ip> is not set. Using 192.168.244.10.
Wed May 24 19:29:23 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Wed May 24 19:29:23 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Wed May 24 19:29:23 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Wed May 24 19:29:23 2017 - [info] MHA::MasterFailover version 0.56.
Wed May 24 19:29:23 2017 - [info] Starting master failover.
Wed May 24 19:29:23 2017 - [info] 
Wed May 24 19:29:23 2017 - [info] * Phase 1: Configuration Check Phase..
Wed May 24 19:29:23 2017 - [info] 
Wed May 24 19:29:24 2017 - [info] GTID failover mode = 0
Wed May 24 19:29:24 2017 - [info] Dead Servers:
Wed May 24 19:29:24 2017 - [info]   192.168.244.10(192.168.244.10:3306)
Wed May 24 19:29:24 2017 - [info] Checking master reachability via MySQL(double check)...
Wed May 24 19:29:24 2017 - [info]  ok.
Wed May 24 19:29:24 2017 - [info] Alive Servers:
Wed May 24 19:29:24 2017 - [info]   192.168.244.20(192.168.244.20:3306)
Wed May 24 19:29:24 2017 - [info]   192.168.244.30(192.168.244.30:3306)
Wed May 24 19:29:24 2017 - [info] Alive Slaves:
Wed May 24 19:29:24 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:29:24 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Wed May 24 19:29:24 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Wed May 24 19:29:24 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log
-bin:enabledWed May 24 19:29:24 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Master 192.168.244.10(192.168.244.10:3306) is dead. Proceed? (yes/NO): yes
Wed May 24 19:29:46 2017 - [error][/usr/local/share/perl5/MHA/MasterFailover.pm, ln309] Last failover was done at 2017/05/24 16:04:54
. Current time is too early to do failover again. If you want to do failover, manually remove /masterha/app1/app1.failover.complete and run this script again.Wed May 24 19:29:46 2017 - [error][/usr/local/share/perl5/MHA/ManagerUtil.pm, ln177] Got ERROR:  at /usr/local/bin/masterha_master_sw
itch line 53.

View Code

后面附上之前提到的测试结果不理想的两种方案

方案一：

模拟步骤如下：

1. master上创建测试表

mysql> use sbtest;
Database changed

mysql> create table sbtest.t1(id int primary key,col1 varchar(10),col2 varchar(10),col3 varchar(10),col4 varchar(10),col5 varchar(10),col6 varchar(10),col7 varchar(10),col8 varchar(10),col9 varchar(10),col10 varchar(10));
Query OK, 0 rows affected (0.33 sec)

2. 关闭Candicate master和Slave的主从复制。

mysql> stop slave;
Query OK, 0 rows affected (0.03 sec)

3. 在master上生成测试数据

创建存储过程

delimiter //
create procedure p1()
begin
declare v1 int default 0;
while v1 <=700000 do
insert into sbtest.t1 values(v1,'aaaaaaaaaa','bbbbbbbbbb','cccccccccc','dddddddddd','eeeeeeeeee','ffffffffff','gggggggggg','hhhhhhhhhh','iiiiiiiiii','jjjjjjjjjj');
set v1=v1+1;
if v1 %1000 =0 then 
commit;
end if;
end while;
end//
delimiter ;

执行存储过程

mysql> call p1;

共执行了两次，生成了500M左右的binlog

[root@node1 ~]# ll -h /var/lib/mysql/mysql-bin.000046 
-rw-rw---- 1 mysql mysql 502M Apr 24 15:18 /var/lib/mysql/mysql-bin.00004

5. 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

在这里，我写了个脚本来实现开启slave复制并kill掉master mysqld进程的功能

# vim monitor_slave.py

#!/usr/bin/python
# coding=utf-8
import MySQLdb
import subprocess
import time


class CheckSlaveStatus:
def __init__(self, host):
        self.conn = MySQLdb.connect(host, "monitor", "monitor123")
        self.cursor = self.conn.cursor()
        self.cursor.execute("start slave")

def get_slave_status(self):
        self.cursor.execute("show slave status")
        slave_status_result = self.cursor.fetchone()
        slave_io_running, slave_sql_running = slave_status_result[10], slave_status_result[11]
return [slave_io_running, slave_sql_running]

def quit(self):
try:
            self.conn.commit()
            self.conn.close()
except Exception as e:
print e


def main():

    check_host = ['192.168.244.30', '192.168.244.20']
    check_slave_status_30 = CheckSlaveStatus(check_host[0])
    check_slave_status_20 = CheckSlaveStatus(check_host[1])

for check_slave_status in [check_slave_status_30, check_slave_status_20]:
print "Begin to check slave status"
while True:
            slave_status = check_slave_status.get_slave_status()
print slave_status
if slave_status == ['Yes', 'Yes']:           
                time.sleep(5)
break

    time.sleep(10)
print "Begin to kill master mysqld"
    command_line="ps -ef |grep mysqld |grep -v grep |awk '{print $2}' |xargs kill -9"
    p = subprocess.Popen(command_line, stdout=subprocess.PIPE, shell=True)
    p.communicate()

    check_slave_status_30.quit()
    check_slave_status_20.quit()

print "Finished"

if __name__ == '__main__':
    main()

执行该脚本

6. 查看MHA的切换日志

Sun May 21 09:46:56 2017 - [warning] Got error on MySQL select ping: 2006 (MySQL server has gone away)
Sun May 21 09:46:56 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 --masteConnection timed out during banner exchange
Sun May 21 09:47:08 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Sun May 21 09:47:08 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Sun May 21 09:47:08 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
to MySQL server at 'reading initial communication packet', system error: 111)
Sun May 21 09:46:57 2017 - [warning] Connection failed 2 time(s)..
Sun May 21 09:46:58 2017 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Sun May 21 09:46:58 2017 - [warning] Connection failed 3 time(s)..
Sun May 21 09:46:59 2017 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Sun May 21 09:46:59 2017 - [warning] Connection failed 4 time(s)..
Monitoring server 192.168.244.20 is reachable, Master is not reachable from 192.168.244.20. OK.
Sun May 21 09:47:01 2017 - [warning] HealthCheck: SSH to 192.168.244.10 is NOT reachable.
Monitoring server 192.168.244.30 is reachable, Master is not reachable from 192.168.244.30. OK.
Sun May 21 09:47:07 2017 - [info] Master is not reachable from all other monitoring servers. Failover should start.
Sun May 21 09:47:07 2017 - [warning] Master is not reachable from health checker!
Sun May 21 09:47:07 2017 - [warning] Master 192.168.244.10(192.168.244.10:3306) is not reachable!
Sun May 21 09:47:07 2017 - [warning] SSH is NOT reachable.
Sun May 21 09:47:07 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 09:47:07 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Sun May 21 09:47:07 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Sun May 21 09:47:07 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Sun May 21 09:47:08 2017 - [info] GTID failover mode = 0
Sun May 21 09:47:08 2017 - [info] Dead Servers:
Sun May 21 09:47:08 2017 - [info]   192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:08 2017 - [info] Alive Servers:
Sun May 21 09:47:08 2017 - [info]   192.168.244.20(192.168.244.20:3306)
Sun May 21 09:47:08 2017 - [info]   192.168.244.30(192.168.244.30:3306)
Sun May 21 09:47:08 2017 - [info] Alive Slaves:
Sun May 21 09:47:08 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:08 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:08 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Sun May 21 09:47:08 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:08 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:08 2017 - [info] Checking slave configurations..
Sun May 21 09:47:08 2017 - [info] Checking replication filtering settings..
Sun May 21 09:47:08 2017 - [info]  Replication filtering check ok.
Sun May 21 09:47:08 2017 - [info] Master is down!
Sun May 21 09:47:08 2017 - [info] Terminating monitoring script.
Sun May 21 09:47:08 2017 - [info] Got exit code 20 (Master dead).
Sun May 21 09:47:08 2017 - [info] MHA::MasterFailover version 0.56.
Sun May 21 09:47:08 2017 - [info] Starting master failover.
Sun May 21 09:47:08 2017 - [info] 
Sun May 21 09:47:08 2017 - [info] * Phase 1: Configuration Check Phase..
Sun May 21 09:47:08 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] GTID failover mode = 0
Sun May 21 09:47:09 2017 - [info] Dead Servers:
Sun May 21 09:47:09 2017 - [info]   192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:09 2017 - [info] Checking master reachability via MySQL(double check)...
Sun May 21 09:47:09 2017 - [info]  ok.
Sun May 21 09:47:09 2017 - [info] Alive Servers:
Sun May 21 09:47:09 2017 - [info]   192.168.244.20(192.168.244.20:3306)
Sun May 21 09:47:09 2017 - [info]   192.168.244.30(192.168.244.30:3306)
Sun May 21 09:47:09 2017 - [info] Alive Slaves:
Sun May 21 09:47:09 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:09 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:09 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Sun May 21 09:47:09 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:09 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:09 2017 - [info] Starting Non-GTID based failover.
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] ** Phase 1: Configuration Check Phase completed.
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] * Phase 2: Dead Master Shutdown Phase..
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] Forcing shutdown so that applications never connect to the current master..
Sun May 21 09:47:09 2017 - [info] Executing master IP deactivation script:
Sun May 21 09:47:09 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=stop 
Disabling the VIP an old master: 192.168.244.10 
Sun May 21 09:47:09 2017 - [info]  done.
Sun May 21 09:47:09 2017 - [warning] shutdown_script is not set. Skipping explicit shutting down of the dead master.
Sun May 21 09:47:09 2017 - [info] * Phase 2: Dead Master Shutdown Phase completed.
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] * Phase 3: Master Recovery Phase..
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] * Phase 3.1: Getting Latest Slaves Phase..
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] The latest binary log file/position on all slaves is mysql-bin.000001:37651149
Sun May 21 09:47:09 2017 - [info] Latest slaves (Slaves that received relay log files to the latest):
Sun May 21 09:47:09 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:09 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:09 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Sun May 21 09:47:09 2017 - [info] The oldest binary log file/position on all slaves is mysql-bin.000001:35083093
Sun May 21 09:47:09 2017 - [info] Oldest slaves:
Sun May 21 09:47:09 2017 - [info]   192.168.244.30(192.168.244.30:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:09 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] * Phase 3.2: Saving Dead Master's Binlog Phase..
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [warning] Dead Master is not SSH reachable. Could not save it's binlogs. Transactions that were not sent to the latest slave (Read_Master_Log_Pos to the tail of the dead master's binlog) were lost.
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] * Phase 3.3: Determining New Master Phase..
Sun May 21 09:47:09 2017 - [info] 
Sun May 21 09:47:09 2017 - [info] Finding the latest slave that has all relay logs for recovering other slaves..
Sun May 21 09:47:10 2017 - [info] HealthCheck: SSH to 192.168.244.20 is reachable.
Sun May 21 09:47:10 2017 - [info] Checking whether 192.168.244.20 has relay logs from the oldest position..
Sun May 21 09:47:10 2017 - [info] Executing command: apply_diff_relay_logs --command=find --latest_mlf=mysql-bin.000001 --latest_rmlp=37651149 --target_mlf=mysql-bin.000001 --target_rmlp=35083093 --server_id=2 --workdir=/tmp --timestamp=20170521094708 --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.000004
 Fast relay log position search succeeded.
 Target relay log file/position found. start_file:mysqld-relay-bin.000004, start_pos:35083256.
Target relay log FOUND!
Sun May 21 09:47:11 2017 - [info] OK. 192.168.244.20 has all relay logs.
Sun May 21 09:47:11 2017 - [info] HealthCheck: SSH to 192.168.244.30 is reachable.
Sun May 21 09:47:13 2017 - [info] Searching new master from slaves..
Sun May 21 09:47:13 2017 - [info]  Candidate masters from the configuration file:
Sun May 21 09:47:13 2017 - [info]   192.168.244.20(192.168.244.20:3306)  Version=5.6.31-log (oldest major version between slaves) log-bin:enabled
Sun May 21 09:47:13 2017 - [info]     Replicating from 192.168.244.10(192.168.244.10:3306)
Sun May 21 09:47:13 2017 - [info]     Primary candidate for the new Master (candidate_master is set)
Sun May 21 09:47:13 2017 - [info]  Non-candidate masters:
Sun May 21 09:47:13 2017 - [info]  Searching from candidate_master slaves which have received the latest relay log events..
Sun May 21 09:47:13 2017 - [info] New master is 192.168.244.20(192.168.244.20:3306)
Sun May 21 09:47:13 2017 - [info] Starting master failover..
Sun May 21 09:47:13 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 09:47:13 2017 - [info] 
Sun May 21 09:47:13 2017 - [info] * Phase 3.3: New Master Diff Log Generation Phase..
Sun May 21 09:47:13 2017 - [info] 
Sun May 21 09:47:13 2017 - [info]  This server has all relay logs. No need to generate diff files from the latest slave.
Sun May 21 09:47:13 2017 - [info] 
Sun May 21 09:47:13 2017 - [info] * Phase 3.4: Master Log Apply Phase..
Sun May 21 09:47:13 2017 - [info] 
Sun May 21 09:47:13 2017 - [info] *NOTICE: If any error happens from this phase, manual recovery is needed.
Sun May 21 09:47:13 2017 - [info] Starting recovery on 192.168.244.20(192.168.244.20:3306)..
Sun May 21 09:47:13 2017 - [info]  This server has all relay logs. Waiting all logs to be applied.. 
Sun May 21 09:47:56 2017 - [info]   done.
Sun May 21 09:47:56 2017 - [info]  All relay logs were successfully applied.
Sun May 21 09:47:56 2017 - [info] Getting new master's binlog name and position..
Sun May 21 09:47:56 2017 - [info]  mysql-bin.000010:166054508
Sun May 21 09:47:56 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.000010', MASTER_LOG_POS=166054508, MASTER_USER='repl', MASTER_PASSWORD='xxx';
Sun May 21 09:47:56 2017 - [info] Executing master IP activate script:
Sun May 21 09:47:56 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 09:47:59 2017 - [info]  OK.
Sun May 21 09:47:59 2017 - [info] ** Finished master recovery successfully.
Sun May 21 09:47:59 2017 - [info] * Phase 3: Master Recovery Phase completed.
Sun May 21 09:47:59 2017 - [info] 
Sun May 21 09:47:59 2017 - [info] * Phase 4: Slaves Recovery Phase..
Sun May 21 09:47:59 2017 - [info] 
Sun May 21 09:47:59 2017 - [info] * Phase 4.1: Starting Parallel Slave Diff Log Generation Phase..
Sun May 21 09:47:59 2017 - [info] 
Sun May 21 09:47:59 2017 - [info] -- Slave diff file generation on host 192.168.244.30(192.168.244.30:3306) started, pid: 3606. Check tmp log /masterha/app1/192.168.244.30_3306_20170521094708.log if it takes time..
Sun May 21 09:48:04 2017 - [info] 
Sun May 21 09:48:04 2017 - [info] Log messages from 192.168.244.30 ...
Sun May 21 09:48:04 2017 - [info] 
Sun May 21 09:47:59 2017 - [info] Server 192.168.244.30 received relay logs up to: mysql-bin.000001:35083093
Sun May 21 09:47:59 2017 - [info] Need to get diffs from the latest slave(192.168.244.20) up to: mysql-bin.000001:37651149 (using the latest slave's relay logs)
Sun May 21 09:47:59 2017 - [info] Connecting to the latest slave host 192.168.244.20, generating diff relay log files..
Sun May 21 09:47:59 2017 - [info] Executing command: apply_diff_relay_logs --command=generate_and_send --scp_user=root --scp_host=192.168.244.30 --latest_mlf=mysql-bin.000001 --latest_rmlp=37651149 --target_mlf=mysql-bin.000001 --target_rmlp=35083093 --server_id=2 --diff_file_readtolatest=/tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog --workdir=/tmp --timestamp=20170521094708 --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 09:48:04 2017 - [info] 
    Opening /var/lib/mysql/relay-log.info ... ok.
    Relay log found at /var/lib/mysql, up to mysqld-relay-bin.000004
 Fast relay log position search succeeded.
 Target relay log file/position found. start_file:mysqld-relay-bin.000004, start_pos:35083256.
 Concat binary/relay logs from mysqld-relay-bin.000004 pos 35083256 to mysqld-relay-bin.000004 EOF into /tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.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.000004 position 35083256 to tail(37651312).. ok.
 Binlog Checksum enabled
 Binlog Checksum enabled
 Concat succeeded.
 Generating diff relay log succeeded. Saved at /tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog .
scp node2:/tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog to root@192.168.244.30(22) succeeded.
Sun May 21 09:48:04 2017 - [info]  Generating diff files succeeded.
Sun May 21 09:48:04 2017 - [info] End of log messages from 192.168.244.30.
Sun May 21 09:48:04 2017 - [info] -- Slave diff log generation on host 192.168.244.30(192.168.244.30:3306) succeeded.
Sun May 21 09:48:04 2017 - [info] Generating relay diff files from the latest slave succeeded.
Sun May 21 09:48:04 2017 - [info] 
Sun May 21 09:48:04 2017 - [info] * Phase 4.2: Starting Parallel Slave Log Apply Phase..
Sun May 21 09:48:04 2017 - [info] 
Sun May 21 09:48:04 2017 - [info] -- Slave recovery on host 192.168.244.30(192.168.244.30:3306) started, pid: 3613. Check tmp log /masterha/app1/192.168.244.30_3306_20170521094708.log if it takes time..
Sun May 21 09:48:12 2017 - [info] 
Sun May 21 09:48:12 2017 - [info] Log messages from 192.168.244.30 ...
Sun May 21 09:48:12 2017 - [info] 
Sun May 21 09:48:04 2017 - [info] Starting recovery on 192.168.244.30(192.168.244.30:3306)..
Sun May 21 09:48:04 2017 - [info]  Generating diffs succeeded.
Sun May 21 09:48:04 2017 - [info] Waiting until all relay logs are applied.
Sun May 21 09:48:04 2017 - [info]  done.
Sun May 21 09:48:04 2017 - [info] Getting slave status..
Sun May 21 09:48:04 2017 - [info] This slave(192.168.244.30)'s Exec_Master_Log_Pos(mysql-bin.000001:35083010) does not equal to Read_Master_Log_Pos(mysql-bin.000001:35083093). It is likely that relay log was cut during transaction. Need to recover from Exec_Master_Log_Pos.
Sun May 21 09:48:04 2017 - [info] Saving local relay logs from exec pos to read pos on 192.168.244.30: from mysqld-relay-bin.000004:35083173 to the end of the relay log..
Sun May 21 09:48:04 2017 - [info] Executing command : save_binary_logs --command=save --start_file=mysqld-relay-bin.000004  --start_pos=35083173 --output_file=/tmp/relay_from_exec_to_read_192.168.244.30_3306_20170521094708.binlog --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --relay_log_info=/var/lib/mysql/relay-log.info  --binlog_dir=/var/lib/mysql/ 
Sun May 21 09:48:05 2017 - [info] 
  Creating /tmp if not exists..    ok.
 Concat binary/relay logs from mysqld-relay-bin.000004 pos 35083173 to mysqld-relay-bin.000004 EOF into /tmp/relay_from_exec_to_read_192.168.244.30_3306_20170521094708.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.000004 position 35083173 to tail(35083256).. ok.
 Binlog Checksum enabled
 Binlog Checksum enabled
 Concat succeeded.
Sun May 21 09:48:05 2017 - [info] Connecting to the target slave host 192.168.244.30, running recover script..
Sun May 21 09:48:05 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/relay_from_exec_to_read_192.168.244.30_3306_20170521094708.binlog,/tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog --workdir=/tmp --target_version=5.6.31-log --timestamp=20170521094708 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 --slave_pass=xxx
Sun May 21 09:48:12 2017 - [info] 
 Concat all apply files to /tmp/total_binlog_for_192.168.244.30_3306.20170521094708.binlog ..
 Copying the first binlog file /tmp/relay_from_exec_to_read_192.168.244.30_3306_20170521094708.binlog to /tmp/total_binlog_for_192.168.244.30_3306.20170521094708.binlog.. ok.
  Dumping binlog head events (rotate events), skipping format description events from /tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog..  Binlog Checksum enabled
 Binlog Checksum enabled
dumped up to pos 283. ok.
/tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog has effective binlog events from pos 283.
  Dumping effective binlog data from /tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog position 283 to tail(2568339).. ok.
 Concat succeeded.
All apply target binary logs are concatinated at /tmp/total_binlog_for_192.168.244.30_3306.20170521094708.binlog .
MySQL client version is 5.6.31. Using --binary-mode.
Applying differential binary/relay log files /tmp/relay_from_exec_to_read_192.168.244.30_3306_20170521094708.binlog,/tmp/relay_from_read_to_latest_192.168.244.30_3306_20170521094708.binlog on 192.168.244.30:3306. This may take long time...
Applying log files succeeded.
Sun May 21 09:48:12 2017 - [info]  All relay logs were successfully applied.
Sun May 21 09:48:12 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 09:48:12 2017 - [info]  Executed CHANGE MASTER.
Sun May 21 09:48:12 2017 - [info]  Slave started.
Sun May 21 09:48:12 2017 - [info] End of log messages from 192.168.244.30.
Sun May 21 09:48:12 2017 - [info] -- Slave recovery on host 192.168.244.30(192.168.244.30:3306) succeeded.
Sun May 21 09:48:12 2017 - [info] All new slave servers recovered successfully.
Sun May 21 09:48:12 2017 - [info] 
Sun May 21 09:48:12 2017 - [info] * Phase 5: New master cleanup phase..
Sun May 21 09:48:12 2017 - [info] 
Sun May 21 09:48:12 2017 - [info] Resetting slave info on the new master..
Sun May 21 09:48:12 2017 - [info]  192.168.244.20: Resetting slave info succeeded.
Sun May 21 09:48:12 2017 - [info] Master failover to 192.168.244.20(192.168.244.20:3306) completed successfully.
Sun May 21 09:48:12 2017 - [info] Deleted server1 entry from /etc/masterha/app1.cnf .
Sun May 21 09:48:12 2017 - [info] 

----- 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 192.168.244.20(192.168.244.20:3306) 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): Generating differential relay logs up to 192.168.244.20(192.168.244.20:3306)succeeded.
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 09:48:12 2017 - [info] Sending mail..
Unknown option: conf

View Code

方案二

对Candicate master上和Slave上的网卡进行带宽限制

Candicate master

[root@node2 ~]# /sbin/tc qdisc add dev eth0 root tbf rate 50kbit latency 50ms burst 15kb

Slave

/sbin/tc qdisc add dev eth0 root tbf rate 80kbit latency 50ms burst 15kb

注意：Candicate master的网卡限制在50kbit，slave的网卡限制在80kbit，

要确保Candicate master的小于slave的，这样才能模拟出Candicate master上relay log的位置小于slave上relay log的位置。

关于如何确认网卡的速率控制到多大合适，

可通过压测，测试master的吞吐量，

以及结合如下方法，测试主机之间的传输速率来确定网卡合适的速率。

[root@node1 ~]# dd if=/dev/zero of=hello.txt bs=100M count=1

[root@node1 ~]# time scp hello.txt 192.168.244.20:/tmp/

hello.txt 100% 100MB 2.6MB/s 00:39

参考

《深入浅出MySQL》

秒客网

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

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