隨着業務的變更，需要在新的一台CentOS下部署MariaDB數據庫，並把之前的數據庫文件遷移到新數據庫中。之前想來應該不會太復雜，結果沒想到也折騰了一天多。記錄下希望今后能避免類似問題，再次遇到此類問題時也不用到處搜索。
在新的CentOS服務器上安裝部署MariaDB，安裝過很多次了，所以這塊就不多累述。新版本的CentOS都有自帶的MariaDB，所以得先把自帶的卸載了再裝自己想安裝的版本。接下來就是修改數據目錄的操作，這塊就得詳細記錄下。
第一步：停止MariaDB服務，並修改數據目錄
1、執行命令，停止MariaDB服務
systemctl stop mariadb
2、在 /home 下創建新的數據文件夾
mkdir mysql
3、修改my.cnf （新增紅色部分）
[mysqld] datadir=/home/mysql socket=/home/mysql/mysql.sock skip-name-resolve
4、修改 server.cnf (紅色部分)
[mysqld]
datadir=/home/mysql
5、重新執行安裝命令：mysql_install_db --defaults-file=/etc/my.cnf --datadir=/home/mysql/ --user=mysql
[root@localhost home]# mysql_install_db --defaults-file=/etc/my.cnf --datadir=/home/mysql/ --user=mysql Installing MariaDB/MySQL system tables in '/home/mysql/' ... OK To start mysqld at boot time you have to copy support-files/mysql.server to the right place for your system PLEASE REMEMBER TO SET A PASSWORD FOR THE MariaDB root USER ! To do so, start the server, then issue the following commands: '/usr/bin/mysqladmin' -u root password 'new-password' '/usr/bin/mysqladmin' -u root -h localhost.localdomain password 'new-password' Alternatively you can run: '/usr/bin/mysql_secure_installation' which will also give you the option of removing the test databases and anonymous user created by default. This is strongly recommended for production servers. See the MariaDB Knowledgebase at http://mariadb.com/kb or the MySQL manual for more instructions. You can start the MariaDB daemon with: cd '/usr' ; /usr/bin/mysqld_safe --datadir='/home/mysql/' You can test the MariaDB daemon with mysql-test-run.pl cd '/usr/mysql-test' ; perl mysql-test-run.pl Please report any problems at http://mariadb.org/jira The latest information about MariaDB is available at http://mariadb.org/. You can find additional information about the MySQL part at: http://dev.mysql.com Consider joining MariaDB's strong and vibrant community: https://mariadb.org/get-involved/
6、重啟數據庫服務
[root@localhost mysql]# systemctl start mariadb Job for mariadb.service failed because the control process exited with error code. See "systemctl status mariadb.service" and "journalctl -xe" for details.
經核查日志文件，提示沒有權限問題導致的：
第二步：解決權限不足的問題
1、根據提示信息，顯示數據庫服務不能操作新建目錄
1.1、核查之前目錄所用的權限
1.2、經核實是用的mysql用戶組及用戶，所以新建的文件夾也應該要加此用戶組
[root@localhost home]# chown -R mysql:mysql /home/mysql [root@localhost home]# chomd 775 /home/mysql bash: chomd: 未找到命令... 相似命令是： 'chmod' [root@localhost home]# chmod 775 /home/mysql [root@localhost home]# ll 總用量 4 drwxrwxr-x. 16 mysql mysql 4096 7月 10 17:53 admin drwxrwxr-x. 9 mysql mysql 277 7月 14 10:31 data drwxrwxr-x 2 mysql mysql 130 7月 14 10:41 mysql
2、再次重啟數據庫服務，結果還是失敗，還是提示沒有權限
Jul 14 10:32:00 localhost systemd: mariadb.service failed. Jul 14 10:35:13 localhost systemd: Starting MariaDB 10.2.32 database server... Jul 14 10:35:13 localhost mysqld: 2020-07-14 10:35:13 140669217863872 [Note] /usr/sbin/mysqld (mysqld 10.2.32-MariaDB) starting as process 16051 ... Jul 14 10:35:13 localhost mysqld: 2020-07-14 10:35:13 140669217863872 [Warning] Could not increase number of max_open_files to more than 16364 (request: 32222) Jul 14 10:35:13 localhost mysqld: 2020-07-14 10:35:13 140669217863872 [Warning] Can't create test file /home/data/localhost.lower-test Jul 14 10:35:13 localhost mysqld: #007/usr/sbin/mysqld: Can't change dir to '/home/data/' (Errcode: 13 "Permission denied") Jul 14 10:35:13 localhost mysqld: 2020-07-14 10:35:13 140669217863872 [ERROR] Aborting Jul 14 10:35:14 localhost systemd: mariadb.service: main process exited, code=exited, status=1/FAILURE Jul 14 10:35:14 localhost systemd: Failed to start MariaDB 10.2.32 database server. Jul 14 10:35:14 localhost systemd: Unit mariadb.service entered failed state. Jul 14 10:35:14 localhost systemd: mariadb.service failed. Jul 14 10:40:01 localhost systemd: Started Session 124 of user root. Jul 14 10:45:21 localhost systemd: Starting MariaDB 10.2.32 database server... Jul 14 10:45:21 localhost mysqld: 2020-07-14 10:45:21 140469303916736 [Note] /usr/sbin/mysqld (mysqld 10.2.32-MariaDB) starting as process 16815 ... Jul 14 10:45:21 localhost mysqld: 2020-07-14 10:45:21 140469303916736 [Warning] Could not increase number of max_open_files to more than 16364 (request: 32222) Jul 14 10:45:21 localhost mysqld: 2020-07-14 10:45:21 140469303916736 [Warning] Can't create test file /home/mysql/localhost.lower-test Jul 14 10:45:21 localhost mysqld: #007/usr/sbin/mysqld: Can't change dir to '/home/mysql/' (Errcode: 13 "Permission denied") Jul 14 10:45:21 localhost mysqld: 2020-07-14 10:45:21 140469303916736 [ERROR] Aborting Jul 14 10:45:21 localhost systemd: mariadb.service: main process exited, code=exited, status=1/FAILURE Jul 14 10:45:21 localhost systemd: Failed to start MariaDB 10.2.32 database server. Jul 14 10:45:21 localhost systemd: Unit mariadb.service entered failed state. Jul 14 10:45:21 localhost systemd: mariadb.service failed.
3、各種度娘后發現要修改此文件配置 （migrated-from-my.cnf-settings.conf）
[root@localhost mysql]# find / -name migrated-from-my.cnf-settings.conf /etc/systemd/system/mariadb.service.d/migrated-from-my.cnf-settings.conf [root@localhost mysql]# vi /etc/systemd/system/mariadb.service.d/migrated-from-my.cnf-settings.conf
[Service]
ProtectHome=false
[root@localhost mysql]# systemctl daemon-reload
4、再次重啟服務，直接成功了。
第三步：拷貝當前正式服務器數據庫文件到新服務器上
1、拷貝到/home/mysql下后，用數據庫查看確實也能看到數據庫了，但是發現卻不能正常操作表，提示：
ERROR 1932 (42S02): Table 'users' doesn't exist in engine
度娘后發現要同步 ibdata1 此文件才行。
2、停止服務后，同步時需要完全覆蓋當前的文件，重啟數據庫服務報錯。
Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] /usr/sbin/mysqld (mysqld 10.2.32-MariaDB) starting as process 18711 ... Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Warning] Could not increase number of max_open_files to more than 16364 (request: 32222) Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Uses event mutexes Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Compressed tables use zlib 1.2.7 Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Using Linux native AIO Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Number of pools: 1 Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Using SSE2 crc32 instructions Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [Note] InnoDB: Completed initialization of buffer pool Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069184190208 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority(). Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [ERROR] InnoDB: The innodb_system data file 'ibdata1' must be writable Jul 14 11:11:13 localhost mysqld: 2020-07-14 11:11:13 140069742344384 [ERROR] InnoDB: The innodb_system data file 'ibdata1' must be writable
根據此提示，重新加下權限即可
chown -R mysql:mysql /home/mysql
再次重啟就沒有問題了。數據表也能正常操作了。