Take a look at how to write a MySQL backup script

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Foreword:

The importance of database backup is self-evident, especially in a production environment, where any data loss may have serious consequences. Therefore, no matter what the environment, we should have a corresponding backup strategy to back up the database regularly. In MySQL, the more commonly used logical backup tool is mysqldump. This article will introduce the method of scheduled backup of MySQL.

1. Develop a suitable backup strategy

For different database environments, we should consider different backup strategies. When formulating a backup strategy, the following factors should be considered:

• Physical backup or logical backup. This can be determined by the size of the database. For example, if it is less than 100G, use logical backup, and if it is larger than 100G, use physical backup.
• Backup file retention time. This can be determined by the size of the disk, and is generally retained for at least 7 days.
• Backup execution time. It is generally placed during low business peak periods, such as performing backup operations in the early morning.
• Backup interval. It is generally recommended to backup once a day. If the system is not too important, the backup interval can be extended.
• Whether there is a slave library. If there is a slave database, it is recommended to backup it on the slave database to reduce the pressure on the main database.
  

2.Linux system backup script

Under the Linux system, we can use crontab scheduled tasks to execute the backup script. If you If you don’t know crontab yet, you can refer to the following introduction to learn it quickly.

crontab is a command, common in Unix and Unix-like operating systems, used to set instructions to be executed periodically.

Format:

* * * * * command
Time-sharing day-month-week command

The first column indicates minutes 1 to 59 every Minutes are represented by * or */1
The second column represents hours 1 to 23 (0 represents 0 o'clock)
The third column represents dates 1 to 31
The fourth column represents months 1 to 12
Column 5 identifies the day of the week from 0 to 6 (0 means Sunday)
The command to be run in column 6

crontab -e Edits the scheduled task settings under this user
crontab -l Lists the All scheduled tasks under the user

Now let’s formally write the backup script. Without further ado, let’s give the script template first:

#!/bin/bash
# -------------------------------------------------------------------------------
# FileName:  mysql_backup.sh 
# Describe:  Used for database backup
# Revision:  1.0
# Date:    2020/08/11
# Author:   wang

# 设置mysql的登录用户名和密码(根据实际情况填写)
mysql_user = "root"
mysql_password = "yourpassword"
mysql_host = "localhost"
mysql_port = "3306"
backup_dir = /data/mysql_backup

dt=date +'%Y%m%d_%H%M'
echo "Backup Begin Date:" $(date +"%Y-%m-%d %H:%M:%S")

# 备份全部数据库
mysqldump -h$mysql_host -P$mysql_port -u$mysql_user -p$mysql_password -R -E --all-databases --single-transaction > $backup_dir/mysql_backup_$dt.sql

find $backup_dir -mtime +7 -type f -name '*.sql' -exec rm -rf {} \;
echo "Backup Succeed Date:" $(date +"%Y-%m-%d %H:%M:%S")

The above script can be modified according to the actual situation, such as backing up a certain libraries, retention time changes, and more. After writing the script, pay attention to debugging. After debugging is completed, it can be deployed. For example, if we plan to perform backup at 2 am every day, we can set up a scheduled task like this.

# 注意脚本执行权限及修改脚本路径
00 02 * * * sh /root/scripts/mysql_backup.sh > /root/scripts/mysql_backup.log 2>&1

3. Windows system backup script

The Windows system backup script is similar, except that it becomes a bat script, and you need to set up scheduled tasks for regular execution. For example, we can create a MySQLdata_Bak directory under the E drive, and create a mysql_backup directory under this directory to store backup files. mysql_bak.bat is a backup script. The content of the script is as follows (automatically delete backup files 7 days ago):

rem auther:wang
rem date:20200811
rem ******MySQL backup start********
@echo off
forfiles /p "E:\MySQLdata_Bak\mysql_backup" /m backup_*.sql -d -7 /c "cmd /c del /f @path"
set "Ymd=%date:~0,4%%date:~5,2%%date:~8,2%0%time:~1,1%%time:~3,2%%time:~6,2%"
"E:\mysql5.7.23\bin\mysqldump" -uroot -p123456 -P3306 --default-character-set=utf8 -R -E --single-transaction --all-databases > "E:\MySQLdata_Bak\mysql_backup\backup_%Ymd%.sql"
@echo on
rem ******MySQL backup end********

The above script is for reference only and can be slightly modified according to your own environment. Similarly, after script debugging is completed, you can add scheduled tasks. If you don't know about Windows scheduled tasks, you can download it on Baidu, which is more convenient and simple.

4. Backup availability verification

In addition to backup, a very important thing is to verify the availability of backup data. Imagine how uncomfortable it would be when you need to perform data recovery and suddenly find that the past backup data is invalid. After many friends write the backup script and add it to the scheduled task, they just check whether the scheduled task is executed or if there are files in the backup directory and no longer pay attention. Often, they only discover that there is a problem with the backup data when they need to use the backup file.

Currently, there is no very convenient way to verify the data of backup files. What is more commonly used is to pull out the backup files regularly to do backup and recovery drills. For example, doing backup and recovery drills once a month can effectively improve backup. File availability and peace of mind.

So, don’t think that everything is foolproof if you have a backup. You should also check whether the backup script is executed correctly and whether the content of the produced backup script is available. It is best to do recovery drills regularly.

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