Backup & Restore of Mariadb Server

Hello, again!

This is just a small blog post on how to backup and restore a MariaDB server, without using MysqlDump, but by directly copying the files in /var/lib/mysql.

Backing up

First of course we need to shutdown mariadb.

# systemctl status mariadb

# systemctl stop mariadb

Copying files:

tar zcvf database_backup_`date +%F`.tgz /var/lib/mysql

Restoring

When putting things back, things start to go wrong¹.

Copying the files to a new host, causes this:

2020-04-14 10:45:32 0 [ERROR] InnoDB: Operating system error number 13 in a file operation. 2020-04-14 10:45:32 0 [ERROR] InnoDB: The error means mysqld does not have the access rights to the directory. 2020-04-14 10:45:32 0 [ERROR] InnoDB: os_file_get_status() failed on './ibdata1'. Can't determine file permissions

So, if the below code works, than SELinux is causing the issue:

sudo semanage permissive -a mysqld_t

Now you added mysql_t to permissive, as shown by the below printout:

]# semanage permissive -l

Builtin Permissive Types


Customized Permissive Types

mysqld_t

Turning it back to enforcing, means running:

# semanage permissive -d mysqld_t
libsemanage.semanage_direct_remove_key: Removing last permissive_mysqld_t module (no other permissive_mysqld_t module exists at another priority).

We need to relabel the new /var/lib/mysql directory:

sudo semanage fcontext -a -t mysqld_db_t "/var/lib/mysql(/.*)?"
sudo restorecon -Rv /var/lib/mysql

Checking the current file contexts:

$ ls --directory --context /var/lib/mysql
unconfined_u:object_r:mysqld_db_t:s0 /var/lib/mysql

MariaBackup

I need to check out MariaBackup^{2 3}, as a better solution for creating backups compared to mysqldump.

References

[1] Security-Enhanced Linux with MariaDB

https://mariadb.com/kb/en/selinux/

[2] Backing up and restoring databases

https://mariadb.com/kb/en/backing-up-and-restoring-databases/

[3] MariaBackup

https://mariadb.com/kb/en/mariabackup/

[4] Full Backup and Restore with MariaBackup

https://mariadb.com/kb/en/full-backup-and-restore-with-mariabackup/