Three methods of MySQL backup

Hello everyone , I meet you again , I'm your friend, Quan Jun .

Catalog

One 、 Purpose of backup

Two 、 Backup issues to consider

3、 ... and 、 The type of backup

Four 、 Backup objects

5、 ... and 、 Implementation of backup and recovery

1、 utilize select into outfile Realize data backup and restore

2、 utilize mysqldump Tools backup and restore data

3、 utilize lvm Snapshot realizes almost hot standby data backup and recovery

4、 be based on Xtrabackup Backup and restore

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The essence of backup is to save a data set as a copy , But the original data will keep changing , Therefore, using backup can only restore the data before the data changes . After the change ？ So it's important to make a good backup strategy .

One 、 Purpose of backup

Doing disaster recovery ： Recover and restore the damaged data

Demand changes ： Due to the change of demand, the data needs to be restored before the change

test ： Test whether the new function is available

Two 、 Backup issues to consider

How long data loss can be tolerated ;

How long does it take to recover data ;

Whether it is necessary to provide continuous services during recovery ;

The object of recovery , It's the whole library , Multiple tables , Or a single library , A single watch .

3、 ... and 、 The type of backup

1、 Depending on whether the database needs to be offline

Cold standby （cold backup）： It needs to be closed mysql service , Read and write requests are not allowed ;

Warm preparation （warm backup）： Service online , But only read requests are supported , Write request is not allowed ;

Hot standby （hot backup）： While backing up , Business is not affected .

notes ： 1、 This type of backup , It depends on the needs of the business , Not backup tools 2、MyISAM Hot standby is not supported ,InnoDB Support hot standby , But special tools are needed

2、 Depending on the range of data sets to be backed up

Full backup ：full backup, Back up all character sets .

Incremental backup : incremental backup Data that has changed since the last full or incremental backup , Not to be used alone , With full backup , The frequency of backups depends on how often the data is updated .

Differential backup ：differential backup Data changed since last full backup .

Recommended recovery strategy ：

Completely + The incremental + Binary log

Completely + differences + Binary log

3、 According to the backup data or files

The physical backup ： Direct backup of data files

advantage ：

Backup and recovery operations are relatively simple , Be able to cross mysql Version of ,

Fast recovery , Belongs to the file system level

Suggest ：

Don't assume that backups are always available , To test

mysql>check tables; Check whether the table is available

Logical backup : Back up the data and code in the table

advantage ：

It's easy to recover 、

The result of the backup is ASCII file , Can edit

It's not about the storage engine

It can be backed up and restored through the network

shortcoming ：

Backup or recovery requires mysql Server processes participate in

Backup results take up more space ,

Floating point numbers may lose precision

After restoration , The miniature needs to be rebuilt

Four 、 Backup objects

1、 data ;

2、 The configuration file ;

3、 Code ： stored procedure 、 Storage function 、 trigger

4、os Related configuration files

5、 Copy related configuration

6、 Binary log

5、 ... and 、 Implementation of backup and recovery

1、 utilize select into outfile Realize data backup and restore

1.1 Back up the data that needs to be backed up

mysql> use hellodb;     // open hellodb library 
mysql> select * from students;   see students Properties of 
mysql> select * from students where Age > 30 into outfile ‘/tmp/stud.txt’ ;   // Back up the information of students older than 30 

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Be careful ：

The directory path of the backup must allow the current operation mysql Users of the server mysql Have access rights

After the backup is completed, you need to remove the backed up files from tmp Copy the directory , Otherwise, the purpose of backup will be lost

go back to tmp Check the file just backed up under the directory

[[email protected] ~]# cd /tmp

[[email protected] tmp]# cat stud.txt

3Xie Yanke53M216

4Ding Dian32M44

6Shi Qing46M5\N

13Tian Boguang33M2\N

25Sun Dasheng100M\N\N

[[email protected] tmp]#

You will find it is a text file . So you can't import the database directly . Need to use load data infile recovery

go back to mysql Server side , Delete older than 30 Users of , Simulation data is destroyed

mysql> delete from students where Age > 30;

mysql> load data infile ‘/tmp/stud.txt’ into table students;

2、 utilize mysqldump Tools backup and restore data

mysqldump Often used for warm preparation , So we first need to apply a read lock to the data we want to back up ,

2.1 Apply read lock ：

1. Add options directly during backup

–lock-all-tables It is to apply read locks to all tables of the database to be backed up

–lock-table Apply read lock to single table only , Even backing up the entire database , It also imposes a read lock on a table when we back it up , Therefore, it is suitable for backing up a single table

2、 Write commands on the server ,

mysql> flush tables with read lock; Apply lock , Means to synchronize all the tables in memory to disk , Then apply read lock

mysql> flush tables with read lock; Release read lock

But that's right. InnoDB In terms of storage engine , Although you can also request Dao read lock , But it doesn't mean that all its data has been synchronized to the disk , So when faced with InnoDB When , We're going to use mysql> show engine innodb status; have a look InnoDB All the data has been synchronized to the disk , Before the backup operation .

2.2 Backup strategy ：

Full backup + Incremental backup + Binary log

Demonstrate the process of backup ;

2.3 First make a full backup of the database ：

[[email protected] ~]# mysqldump -uroot --single-transaction --master-data=2 --databases hellodb > /backup/hellodb_`date +%F`.sql
--single-transaction:  Based on this option, hot standby can be realized InnoDB surface ; therefore , You don't need to use it at the same time --lock-all-tables;
   --master-data=2   Record the location of the binary log at the time of backup , And comment out ,1 It is not annotated 
   --databases hellodb  Specify the database to back up 
 Then back mysql Server side ,

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2.4 go back to mysql Update data on the server

mysql> create table tb1(id int);  Create table 
mysql> insert into tb1 values (1),(2),(3);   insert data , This is just a demonstration , Casually inserted a few data 

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2.5 First check the location recorded in the full backup file ：

[[email protected] backup]# cat hellodb_2013-09-08.sql | less
-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000013', MASTER_LOG_POS=15684;  The location of the binary log is recorded 

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2.6 Back to the server ：

mysql> show master status;  Display the location of the binary log at this time 
  From the location recorded in the backup file to our current location , That is, the incremental part 
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000004 |      15982 |              |                  |
+------------------+----------+--------------+------------------+

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2.7 Make incremental backups

[[email protected] backup]# mysqlbinlog --start-position=15694 --stop-position=15982
/mydata/data/mysql-bin.000013 > /backup/hellodb_`date +$F_%H`.sql

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2.8 Back to the server

mysql> insert into tb1 values (4),(5);  Insert some values 
mysql> drop database hellodb;    Delete hellodb library 

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2.9 Export the binary log this time ：

[[email protected] backup]# mysqlbinlog --start-position=15982 /mydata/data/mysql-bin.000013  View the location of the binary log when deleting 
[[email protected] backup]# mysqlbinlog --start-position=15982 --stop-position=16176 /mydata/data/mysql-bin.000013 > /tmp/hellodb.sql  // Export binary log 

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2.10 First, let mysql offline

 Back to the server ：
mysql> set sql_log_bin=0;   Close binary log 
mysql> flush logs;  Scroll down the log 

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2.11 Simulation database corruption

mysql> drop database hellodb;

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2.12 Start restoring data ：

[[email protected] ]# mysql < /backup/hellodb_2013-09-08.sql  // Import a full backup file 
[[email protected] ]# mysql < /backup/hellodb_2013-09-08_05.sql // Import incremental backup file 
[[email protected] ]# mysql< hellodb.sql // Import binaries 

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Verification complete , The display results are as we expected

notes ： 1、 Really in the production environment , What we should export is the whole mysql Data in the server , Instead of a single library , So you should use –all-databases 2、 When exporting binary logs , You can directly copy files , But here's the thing , Scroll down the log before backup .

3、 utilize lvm Snapshot realizes almost hot standby data backup and recovery

3.1 Strategy ：

Full backup + Binary log ;

3.2 Get ready ：

notes ： The transaction log must be in the same place as the data file LV On ;

3.3 establish lvm Lvm I won't say much about the creation of , If you want to know, click http://limian.blog.51cto.com/7542175/1256660

3.4 modify mysql The permissions and belonging groups of the files in the main configuration file storage directory , And initialization mysql

[[email protected] ~]# mkdir /mydata/data             // Create a data directory 
[[email protected] ~]# chown mysql:mysql /mydata/data  // Change to group owner 
[[email protected] ~]#
[[email protected] ~]# cd /usr/local/mysql/    // You must stand under this directory      
[[email protected] mysql]# scripts/mysql_install_db --user=mysql --datadir=/mydata/data  // initialization mysql

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3.5 Modify the configuration file ：

  vim /etc/my.cof
  datadir=/mydata/data    Add data directory 
sync_binlog = 1   Turn on this function 

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3.6 Start the service

[[email protected] mysql]# service mysqld start
mysql> set session sql_log_bin=0;   Close binary log 
mysql> source /backup/all_db_2013-09-08.sql    Read backup file 

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3.7 go back to mysql The server ：

mysql> FLUSH TABLES WITH READ LOCK;  Request read lock 
 notes ： Don't quit , Another terminal ：
mysql> SHOW MASTER STATUS;           Check the location of binary files 
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000004 |      107 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
mysql> FLUSH LOGS;   It is recommended to scroll down the log . It will be convenient to back up logs 

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3.8 Export binaries , Create a directory to store separately

[[email protected] ~]# mkdir /backup/limian
[[email protected] ~]# mysql -e 'show master status;' > /backup/limian/binlog.txt
[[email protected] ~]#

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3.9 Create a snapshot of the volume where the data resides ：

[[email protected] ~]# lvcreate -L 100M -s -p r -n mysql_snap /dev/myvg/mydata

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Back to the server , Release read lock

mysql> UNLOCK TABLES;
[[email protected] ~]# mount /dev/myvg/mysql_snap /mnt/data
[[email protected] data]# cp * /backup/limian/
[[email protected] data]#lvremove /dev/myvg/mylv_snap

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3.10 Update the data in the database , And delete the data file in the data directory , Simulation database corruption

mysql>  create table limiantb (id int,name CHAR(10));
mysql> insert into limiantb values (1,'tom');
[[email protected] data]# mysqlbinlog --start-position=187 mysql-bin.000003 > /backup/limian/binlog.sql
[[email protected] backup]# cd /mydata/data/
[[email protected] data]#  rm -rf *
[[email protected] ~]# cp -a /backup/limian/* /mydata/data/
[[email protected] data]# chown mysql:mysql *

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3.11 test

Start the service

[[email protected] data]# service mysqld start
[[email protected] data]# mysql  Login test 
mysql> SHOW DATABASES;
mysql> SET sql_log_bin=0
mysql> source/backup/limian/binlog.sql; # Binary recovery 
mysql> SHOW TABLES;         # View the recovery results 
mysql> SET sql_log_bin=1;   # Turn on binary log 

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notes ： This method realizes the backup of data files close to hot standby , And the data files are placed in lvm Can be flexibly changed according to the size of data lvm Size , The backup method is also very simple .

4、 be based on Xtrabackup Backup and restore

The official site ：www.percona.com

advantage ：

1、 Fast and reliable full backup

2、 Transactions will not be affected during backup

3、 Support data flow 、 Network transmission 、 Compress , So it can effectively save disk resources and network bandwidth .

4、 It can automatically back up the availability of verification data .

install Xtrabackup

[[email protected] ~]# rpm -ivh percona-xtrabackup-2.1.4-656.rhel6.i686.rpm

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The latest version of the software can be downloaded from http://www.percona.com/software/percona-xtrabackup/ get

Be careful ： When backing up the database , We should have permission , However, it should be noted that the user should be given the minimum permission when backing up the database , To ensure safety ,

4.1 Premise ：

You should make sure that you are using a single table, a single table space , Otherwise, single table backup and recovery are not supported .

In the configuration file mysqld Segment plus

innodb_file_per_table = 1

4.2 Backup policy

Full backup + Incremental backup + Binary log

4.3 Prepare a directory for storing backup data

[[email protected] ~]# makdir /innobackup

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4.4 Make a full backup ：

[[email protected] ~]# innobackupex --user=root --password=mypass /innobackup/

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notes ：

1、 Just show it on the last line innobackupex: completed OK!, It means that your backup is correct .

2、 Another thing to note is that after each backup , A directory named after the current time point will be automatically created under the data directory to store the backup data , Let's go and see what we have

[[email protected] 2013-09-12_11-03-04]# ls

backup-my.cnf ibdata1 performance_schema xtrabackup_binary xtrabackup_checkpoints

hellodb mysql test xtrabackup_binlog_info xtrabackup_logfile

[[email protected] 2013-09-12_11-03-04]#

xtrabackup_checkpoints ： Backup type 、 Backup status and LSN( Log serial number ) Scope information ;

xtrabackup_binlog_info ：mysql The location of the binary log file currently in use by the server and the binary log events up to the time of backup .

xtrabackup_logfile ： Non text files ,xtrabackup Your own log file

xtrabackup_binlog_pos_innodb ： Binary log file and its application in InnoDB or XtraDB Table's binary log file position.

backup-my.cnf ： During backup, the data file is about mysqld Configuration of

4.5 go back to mysql The server side updates the data

mysql> use hellodb;
mysql> delete from students where StuID>=24;

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4.6 Incremental backup

innobackupex --user=root --password=mypass --incremental /innobackup/--incremental-basedir=/innobackup/2013-09-12_11-03-04/
--incremental   Specify the backup type 
--incremental-basedir=  Specify which backup this incremental backup is based on , Here is the full backup file , In this way, the incremental backup data can be merged into the full backup 

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4.7 The second increment

Modify the data first

mysql> insert into students (Name,Age,Gender,ClassID,TeacherID) values ('tom',33,'M',2,4);
innobackupex --user=root --password=mypass --incremental /innobackup/ --incremental-basedir=/innobackup/2013-09-12_11-37-01/
  Here, just change the last directory to the data directory of the first incremental backup 

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4.8 The last time the data was changed, but no incremental backup was made

mysql> delete from coc where id=14;

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4.9 Back up binary log files ,( Because the last modification , No incremental backup , Rely on binary logs for point in time recovery )

[[email protected] data]# cp mysql-bin.000003 /tmp/

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4.10 Simulated database crash

[[email protected] data]# service mysqld stop
[[email protected] data]# rm -rf *

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Prepare for recovery

4.11 Do data synchronization for full backup

[[email protected] ~]# innobackupex --apply-log --redo-only /innobackup/2013-09-12_11-03-04/

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4.12 Do data synchronization for the first increment

innobackupex --apply-log --redo-only /innobackup/2013-09-12_11-03-04/ --incremental-basedir=/innobackup/2013-09-12_11-37-01/

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4.13 Do data synchronization for the second increment

innobackupex --apply-log --redo-only /innobackup/2013-09-12_11-03-04/ --incremental-basedir=/innobackup/2013-09-12_11-45-53/
--apply-log  The significance of backup is that there is no commit Transaction revocation of , already commit But it is also applied to the database in the transaction log 

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notes ：

about xtrabackup Speaking of , It is based on transaction log and data file backup , The backed up data may contain uncommitted transactions or transactions that have been committed but have not yet been synchronized to the database file , It should also be pretreated , Synchronize the committed transactions to the data file , Uncommitted transactions should be rolled back . So the database it backs up , It cannot be recovered immediately .

The process of pretreatment ：

First, for the full backup file, only the committed transactions are synchronized to the data file , Pay attention to the increment , You cannot rollback transactions , Otherwise, your incremental backup will have no effect .

Then merge the first incremental backup into the full backup file ,

And so on , Merge the last few increments into the file after the previous merge , In this case , We just need to take a full backup + Binary log , You can do point in time recovery .

4.14 Data recovery

[[email protected] ~]# service mysqld stop
[[email protected] data]# rm -rf *   Simulated database crash 
[[email protected] ~]# innobackupex --copy-back /innobackup/2013-09-12_11-03-04/
--copy-back Database recovery , Follow the location of the backup directory 

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4.15 testing ：

Log in and copy

[[email protected] ~]# cd /mydata/data/
[[email protected] data]# chown mysql:mysql *
[[email protected] data]#service mysqld start

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The test result data is normal .

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