如果要啟用級聯復制,需要在從服務器啟用以下配置；

[mysqld]
log_bin
log_slave_updates

log_slave_updates的作用：
    因為默認從主服務器過來的二進制日誌保存在從服務器的中繼日誌；並應用到本地數據庫；
    但是中間這個從服務器是即便是開啟二進制日誌的記錄功能，他也是不記錄到本地的二進制日誌，
    那麽也就不能將對數據庫的操作再傳輸到從的從服務器上去。當log_slave_updates啟用後，
    從服務器也就能將對主服務器的二進制日誌在本地執行後，也記錄到自己的二進制日誌中；


刪除數據庫就可以幹凈做實驗；
[root@master ~]$systemctl stop mariadb
[root@master ~]$rm -fr /var/lib/mysql/*
[root@master ~]$systemctl start mariadb

主、從、二級從服務器的配置：

[root@master ~]$cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
innodb_file_per_table
log_bin
server-id=1

[root@slave ~]$cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
innodb_file_per_table
server_id=2
read_only
log_bin
log_slave_updates

[root@slave2 ~]$cat  /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
server_id=3

主服務器和從服務器實現主從復制，配置和授權：

主服務器：
MariaDB [(none)]> grant replication slave on *.* to repluser@'192.168.27.%' identified by 'centos';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> show master logs;
+--------------------+-----------+
| Log_name           | File_size |
+--------------------+-----------+
| mariadb-bin.000001 |       264 |
| mariadb-bin.000002 |       401 |
+--------------------+-----------+
2 rows in set (0.00 sec)



中間的從服務器：
CHANGE MASTER TO
MASTER_HOST='192.168.27.7',
MASTER_USER='repluser',
MASTER_PASSWORD='centos',
MASTER_LOG_FILE='mariadb-bin.000001',
MASTER_LOG_POS=245;

MariaDB [(none)]> CHANGE MASTER TO
    -> MASTER_HOST='192.168.27.7',
    -> MASTER_USER='repluser',
    -> MASTER_PASSWORD='centos',
    -> MASTER_LOG_FILE='mariadb-bin.000001',
    -> MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.02 sec)

MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.27.7
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mariadb-bin.000002
          Read_Master_Log_Pos: 401
               Relay_Log_File: mariadb-relay-bin.000003
                Relay_Log_Pos: 687
        Relay_Master_Log_File: mariadb-bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
         Exec_Master_Log_Pos: 401
              Relay_Log_Space: 1269
              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

MariaDB [(none)]> select user from mysql.user;
+----------+
| user     |
+----------+
| root     |
| repluser |
| root     |
|          |
| root     |
|          |
| root     |
+----------+
7 rows in set (0.00 sec)



MariaDB [(none)]> show master logs;
+--------------------+-----------+
| Log_name           | File_size |
+--------------------+-----------+
| mariadb-bin.000001 |       401 |
+--------------------+-----------+
1 row in set (0.00 sec)

二級從服務器上的配置：

在從的從服務器上執行：

[mysqld]
innodb_file_per_table
read-only
server-id=3


CHANGE MASTER TO
MASTER_HOST='192.168.27.17',
MASTER_USER='repluser',
MASTER_PASSWORD='centos',
MASTER_LOG_FILE='mariadb-bin.000001',
MASTER_LOG_POS=401;

數據庫集群的級聯復制完整實現