Centos7
CentOS 7 MariaDB 錯誤“無法啟動 mariadb.service：未找到單元。”
我對 Linux 有點陌生，在 Windows 上的 Virtualbox 中測試各種 LAMP 設置。目前我有一個 Centos 7 VM，我正在嘗試在其上安裝 MariaDB。我在這裡遵循說明：http ://www.tecmint.com/install-lamp-in-centos-7
我跑了
# yum install mariadb-server mariadb根據終端輸出安裝成功，但是當我執行時：
# systemctl start mariadb我明白了
Failed to start mariadb.service: Unit not found.我花了幾個小時在Google上搜尋這個，但似乎沒有什麼能解決我的問題，包括這個（在 mariadb-server 安裝後沒有 mysqld 或 mysql.server）和許多其他文章。
任何幫助是極大的讚賞。
更新 01
我解除安裝了 mariadb：
[root@centos7 admin]# yum remove mysql Loaded plugins: fastestmirror Resolving Dependencies --> Running transaction check ---> Package MariaDB-client.x86_64 0:10.0.30-1.el7.centos will be erased --> Processing Dependency: MariaDB-client for package: MariaDB-server-10.0.30-1.el7.centos.x86_64 --> Running transaction check ---> Package MariaDB-server.x86_64 0:10.0.30-1.el7.centos will be erased --> Finished Dependency Resolution Dependencies Resolved =================================================================================== Package Arch Version Repository Size =================================================================================== Removing: MariaDB-client x86_64 10.0.30-1.el7.centos @mariadb 49 M Removing for dependencies: MariaDB-server x86_64 10.0.30-1.el7.centos @mariadb 237 M Transaction Summary =================================================================================== Remove 1 Package (+1 Dependent package) Installed size: 286 M Is this ok [y/N]: y Downloading packages: Running transaction check Running transaction test Transaction test succeeded Running transaction Erasing : MariaDB-server-10.0.30-1.el7.centos.x86_64 1/2 Erasing : MariaDB-client-10.0.30-1.el7.centos.x86_64 2/2 Verifying : MariaDB-client-10.0.30-1.el7.centos.x86_64 1/2 Verifying : MariaDB-server-10.0.30-1.el7.centos.x86_64 2/2 Removed: MariaDB-client.x86_64 0:10.0.30-1.el7.centos Dependency Removed: MariaDB-server.x86_64 0:10.0.30-1.el7.centos Complete!跑
yum clean all和yum update重新安裝mariadb：
# yum install mariadb-server mariadb Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * Webmin: download.webmin.com * base: anorien.csc.warwick.ac.uk * extras: centos.mirrors.nublue.co.uk * updates: centos.serverspace.co.uk Package mariadb-server is obsoleted by MariaDB-server, trying to install MariaDB-server-10.0.30-1.el7.centos.x86_64 instead Package mariadb is obsoleted by MariaDB-client, trying to install MariaDB-client-10.0.30-1.el7.centos.x86_64 instead Resolving Dependencies --> Running transaction check ---> Package MariaDB-client.x86_64 0:10.0.30-1.el7.centos will be installed ---> Package MariaDB-server.x86_64 0:10.0.30-1.el7.centos will be installed --> Finished Dependency Resolution Dependencies Resolved =================================================================================== Package Arch Version Repository Size =================================================================================== Installing: MariaDB-client x86_64 10.0.30-1.el7.centos mariadb 10 M MariaDB-server x86_64 10.0.30-1.el7.centos mariadb 55 M Transaction Summary =================================================================================== Install 2 Packages Total download size: 65 M Installed size: 65 M Is this ok [y/d/N]: y Downloading packages: (1/2): MariaDB-10.0.30-centos7-x86_64-client.rpm | 10 MB 00:00:22 (2/2): MariaDB-10.0.30-centos7-x86_64-server.rpm | 55 MB 00:01:15 ----------------------------------------------------------------------------------- Total 876 kB/s | 65 MB 01:15 Running transaction check Running transaction test Transaction test succeeded Running transaction Installing : MariaDB-client-10.0.30-1.el7.centos.x86_64 1/2 Installing : MariaDB-server-10.0.30-1.el7.centos.x86_64 2/2 libsemanage.map_file: Unable to open /usr/share/mysql/SELinux/mariadb.pp (No such file or directory). libsemanage.semanage_direct_install_file: Unable to read file /usr/share/mysql/SELinux/mariadb.pp (No such file or directory). /usr/sbin/semodule: Failed on /usr/share/mysql/SELinux/mariadb.pp! Verifying : MariaDB-client-10.0.30-1.el7.centos.x86_64 1/2 Verifying : MariaDB-server-10.0.30-1.el7.centos.x86_64 2/2 Installed: MariaDB-client.x86_64 0:10.0.30-1.el7.centos MariaDB-server.x86_64 0:10.0.30-1.el7.centos Complete!還是不行，什麼給？
# systemctl start mariadb.service Failed to start mariadb.service: Unit not found.更新 02
包版本和大小寫可能有些問題，我使用 mariaDB repos 而不是 centos 進行安裝，所以它選擇了 10.0.30 版本：
]# yum info mariadb-server Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * Webmin: download.webmin.com * base: anorien.csc.warwick.ac.uk * extras: centos.mirrors.nublue.co.uk * updates: centos.serverspace.co.uk Installed Packages Name : MariaDB-server Arch : x86_64 Version : 10.0.30 Release : 1.el7.centos Size : 237 M Repo : installed From repo : mariadb Summary : MariaDB: a very fast and robust SQL database server URL : http://mariadb.org License : GPLv2 Description : MariaDB: a very fast and robust SQL database server : : It is GPL v2 licensed, which means you can use the it free of charge : under the conditions of the GNU General Public License Version 2 : (http://www.gnu.org/licenses/). : : MariaDB documentation can be found at https://mariadb.com/kb : MariaDB bug reports should be submitted through : https://jira.mariadb.org Available Packages Name : mariadb-server Arch : x86_64 Epoch : 1 Version : 5.5.52 Release : 1.el7 Size : 11 M Repo : base/7/x86_64 Summary : The MariaDB server and related files URL : http://mariadb.org License : GPLv2 with exceptions and LGPLv2 and BSD Description : MariaDB is a multi-user, multi-threaded SQL database server. It is a : client/server implementation consisting of a server daemon (mysqld) : and many different client programs and libraries. This package : contains the MariaDB server and some accompanying files and : directories. MariaDB is a community developed branch of MySQL.
進一步的研究表明，在 MariaDB repo (v 10.0.30) 中呼叫服務
mysql而不是 centos repo (v5.5)mariadb，所以這是一個混淆/問題。參考問題：Centos7上的MariaDB，服務還是叫MySql
執行
# service mysql start返回ERROR錯誤檢查
grep: journalctl -xe|grep 'mysqld.*errno'顯示：
/usr/bin/mysqld_safe_helper: Cannot change uid/gid (errno: 1)關注這篇文章似乎已經解決了這個問題，這與 MariaDB 10.0.XX 版本和 SELinux 有關：
https://www.penguinprompt.com/mariadb-10-0-29-update-failure-selinux/
我能夠啟動mysql服務並配置它
mysql_secure_installation