What are the database disaster recovery and failover techniques for learning MySQL?

What are the database disaster recovery and failover techniques for learning MySQL?

1. Background introduction
In today's Internet era, the database is the core of the application, and it stores a large amount of data. However, database servers also encounter various failures, such as hardware failures, network interruptions, power failures, etc. In order to ensure continuous high availability and data security, database disaster recovery and failover have become important tasks in database operation and maintenance. As one of the most popular relational databases, MySQL has a variety of disaster recovery and failover technologies. Here are some commonly used techniques.

2. MySQL disaster recovery skills

1. Master-slave replication
   Master-slave replication is one of the most commonly used technologies in MySQL disaster recovery. Almost all MySQL versions support master-slave replication. Copied from. Through master-slave replication, data from the master database can be copied to one or more slave databases to ensure data backup and availability. When the primary database fails, the secondary database can be easily upgraded to the primary database to achieve fast failover.

The configuration steps for master-slave replication are as follows:
1) Enable the binary log (binlog) function on the primary database and configure a unique server_id.
2) Configure replication parameters on the slave database, such as specifying master_host, master_user, master_password, etc.
3) Start the slave database, connect it to the master database and copy the data.

Sample code:

On Master:

# 在配置文件中开启binlog
[mysqld]
server_id=1
log_bin=mysql-bin

On Slave:

# 在配置文件中配置复制参数
[mysqld]
server_id=2
log_bin=mysql-bin

[mysqldump]
master_host=master_ip
master_user=replication_user
master_password=replication_password

2. Copy chain
   Copy chain refers to copying multiple The databases are connected according to the master-slave replication method to form a chain replication structure. This method can achieve distributed backup and failover of data.

Sample code:

On Master1:

[mysqld]
server_id=1
log_bin=mysql-bin

# 配置与下一个主库的连接
log_slave_updates=1
relay_log=mysql-relay-bin
replicate_do_db=db1
replicate-ignore-db=mysql
replicate-ignore-db=source_db
replicate-ignore-db=destination_db
replicate-ignore-db=performance_schema
replicate-ignore-db=information_schema
replicate-ignore-db=innodb
replicate-ignore-db=slave_lab
replicate-wild_ignore-table=server1_db1.binlogtest*
replicate-wild_ignore-table=*.hg.*,*.git.*
replicate-wild-ignore-table=db2_v2p2_gfhb.*.*
replicate-wild=wild123.blog_table_name_to_replicate
[mysqldump]
master_host=master2_ip
master_user=master2_user
master_password=master2_password

On Master2:

[mysqld]
server_id=2
log_bin=mysql-bin

# 配置与下一个主库的连接
log_slave_updates=1
relay_log=mysql-relay-bin
replicate_do_db=db2
replicate-ignore-db=mysql
replicate-ignore-db=source_db
replicate-ignore-db=destination_db
replicate-ignore-db=performance_schema
replicate-ignore-db=information_schema
replicate-ignore-db=innodb
replicate-ignore-db=slave_lab
replicate-wild_ignore-table=server2_db1.binlogtest*
replicate-wild_ignore-table=*.hg.*,*.git.*
replicate-wild-ignore-table=db3_v2p2_gfhb.*.*
replicate-wild=wild321.blog_table_name_to_replicate
[mysqldump]
master_host=master3_ip
master_user=master3_user
master_password=master3_password

The first two steps are performed on the first master library Configuration, the configuration on the second main library is similar. Each database serves as the slave database of the next master database, thus forming a replication chain.

3. MySQL failover skills

1. Automatic fault detection and switching
   Generally speaking, MySQL failover requires manual intervention for switching, but this method will Cause some downtime. In order to achieve automatic failure detection and switching, heartbeat detection and Failover (failover) mechanisms can be used.

Heartbeat detection: Check whether the main database is alive by regularly sending heartbeat packets to the main database.
Failover mechanism: When heartbeat detection finds that the primary database is unavailable, the slave database is automatically promoted to the primary database and related configurations are updated.

Sample code:

#!/usr/bin/env python
import os
import time

VIP = '192.168.1.100'
Script = '/opt/mysql_failover.sh'

def detect_db():
    while True:
        ret = os.system('ping -c 1 '+VIP)
        if ret:
            print('MySQL is down')
            os.system(Script + ' down')
        else:
            print('MySQL is up')
            os.system(Script + ' up')
        time.sleep(5)

detect_db()

2. Configuring a high-availability cluster
   In addition to automatic fault detection and switching, you can also configure a MySQL high-availability cluster to achieve failover. Commonly used high-availability cluster solutions include Pacemaker and Keepalived.

Pacemaker is a mature open source solution that manages resources and dynamic management in a cluster through a resource manager and decision engine.
Keepalived is a lightweight high-availability solution that relies on VRRP (Virtual Router Redundancy Protocol) and LVS (Linux Virtual Server) to achieve failover.

Both of the above two solutions can provide high availability and automatic failover functions. For specific configuration details, please refer to the official documentation.

In summary, by learning MySQL database disaster recovery and failover skills, you can use master-slave replication to achieve data backup and failover, replication chain to achieve distributed backup, automatic fault detection and switching to achieve automatic failover, and Configure a high-availability cluster to provide high availability. The flexible application of these techniques can not only ensure the continuous availability of the database, but also improve the stability and reliability of the system.

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