使用xtrbackup克隆从库

使用xt rbackup克隆从库

在日常工作中，我们有时候需要在线添加从库，比如线上有一主一从两个数据库，但是由于业务的需要，一台从库的读取无法满足现在的需求，这样就需要我们新建一台从库，克隆slave时，常用参数--slave-info。

--slave-info会将master的binlog文件名和偏移量位置保存到xtrabackup_slave_info文件中

下面的例子，将介绍一主一从情况下在线搭建新的从库，环境如下：

master 10.40.55.11 #主库

slave 10.40.55.36 #从库

newslave 10.40.195.11 # 新的从库

在上述示例中，newslave即为要新搭建的从库。

步骤1、在老的从库上面进行备份：

55.36#innobackupex --defaults-file=/opt/bodaodao/mysql/my.cnf --no-timestamp --user=root --password='123456' --socket=/opt/bodaodao/mysql/mysql.sock --slave-info  /backup/bh
innobackupex: MySQL binlog position: filename 'mysql-bin.000704', position 855838849
innobackupex: MySQL slave binlog position: master host '10.40.55.11', filename 'mysql-bin.000508', position 367627999
160902 07:23:07  innobackupex: Connection to database server closed
160902 07:23:07  innobackupex: completed OK!

查看xtrabackup_slave_info文件内容，这个内容就是为搭建从库时需要change master to的参数：

# tail xtrabackup_slave_info 
CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000508', MASTER_LOG_POS=367627999

步骤2、新从库安装数据库

newslave 195.11 (已安装mysql数据库，过程略)

步骤3、新从库关闭数据库实例

newslave 195.11

mysqladmin -u -p -S down

步骤3、清空数据目录

newslave 195.11

cd /databse/mysql_3306/data/

rm -rf *

步骤4、数据还原

方法一：

在新的slave服务器上进行还原，即192.168.195.11

innobackupex --apply-log --redo-only --user=root --password= --defaults-file=/opt/bodaodao/mysql/my.cnf /backup/bh/2016-09-02

将还原的文件复制到新的从库newslave

cp  -r /backup/bh/2016-09-02/*  /database/mysql_3306/data/

方法二：

#innobackupex --apply-log --redo-only --user=root --password= --defaults-file=/opt/bodaodao/mysql/my.cnf /backup/bh/2016-09-02
160902 17:18:57  innobackupex: completed OK!

#innobackupex --copy-back --user=root --password= --defaults-file=/opt/bodaodao/mysql/my.cnf /backup/bh/2016-09-02

步骤5、赋权

chown -R mysql.mysql /database/mysql_3306/data/

步骤6、

55.11 在主库master上添加对新从库newslave的授权：

mysql>  GRANT REPLICATION SLAVE ON *.* TO 'repl'@'10.40.195.11' IDENTIFIED BY 'repl';  
Query OK, 0 rows affected (0.00 sec)

步骤7、

在新的从库上进行同步：

newslave195.11

mysql>  change master to master_host='10.40.55.11',master_user='repl',master_password='repl',master_log_file='mysql-bin.000508',master_log_pos=367627999,Master_Port=3306;

步骤8、

启动io线程和sql线程，并观察复制是否正常：

mysql> start slave;
mysql> show slave status\G;

查看主库，发现已经有两个线程(Binlog Dump)

mysql> select id,user,host,db,command,time,state,info from information_schema.processlist where command <>'sleep'  order by time;
+----------+-------------+--------------------+------+-------------+---------+------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------+
| id       | user        | host               | db   | command     | time    | state                                                            | info                                                                                                                      |
+----------+-------------+--------------------+------+-------------+---------+------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------+
| 33192167 | root        | localhost          | NULL | Query       |       0 | executing                                                        | select id,user,host,db,command,time,state,info from information_schema.processlist where command <>'sleep'  order by time |
| 31057470 | system user |                    | NULL | Connect     |       0 | Slave has read all relay log; waiting for the slave I/O thread t |                                                                                                                 |
| 33195734 | repl        | 10.40.195.11:27004 | NULL | Binlog Dump |    3634 | Master has sent all binlog to slave; waiting for binlog to be up | NULL                                                                                                                      |
| 31057469 | system user |                    | NULL | Connect     | 3453749 | Waiting for master to send event                                 | NULL                                                                                                                      |
|  4576736 | repl        | 10.40.55.36:18842  | NULL | Binlog Dump | 6277958 | Master has sent all binlog to slave; waiting for binlog to be up | NULL                                                                                                                      |
+----------+-------------+--------------------+------+-------------+---------+------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------+

正常工作，到此在线克隆slave就结束啦。

使用xtrbackup克隆从库

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