systemd 提供自动 MySQL 服务器启动和关闭。它还支持使用 systemctl 命令进行手动服务器管理。例如：systemd provides automatic MySQL server startup and shutdown. It also enables manual server management using the systemctl command. For example:

$> systemctl {start|stop|restart|status} mysqld

或者，使用 service 命令（参数相反），该命令与 System V 系统兼容：Alternatively, use the service command (with the arguments reversed), which is compatible with System V systems:

$> service mysqld {start|stop|restart|status}

对 systemd 的支持包括以下文件：Support for systemd includes these files:

要添加或更改 MySQL 的 systemd 选项，可以使用以下方法：To add or change systemd options for MySQL, these methods are available:

要使用本地化的 systemd 配置文件，请创建 /etc/systemd/system/mysqld.service.d 目录（如果不存在）。在该目录中，创建一个文件，其中包含列出所需设置的 [Service] 部分。例如：To use a localized systemd configuration file, create the /etc/systemd/system/mysqld.service.d directory if it does not exist. In that directory, create a file that contains a [Service] section listing the desired settings. For example:

[Service]
LimitNOFILE=max_open_files
Nice=nice_level
LimitCore=core_file_limit
Environment="LD_PRELOAD=/path/to/malloc/library"
Environment="TZ=time_zone_setting"

这里的讨论使用override.conf作为该文件的名称。较新版本的 systemd 支持以下命令，该命令会打开编辑器并允许您编辑文件：The discussion here uses override.conf as the name of this file. Newer versions of systemd support the following command, which opens an editor and permits you to edit the file:

systemctl edit mysqld  # RPM platforms
systemctl edit mysql   # Debian platforms

每当您创建或更改 override.conf 时，都会重新加载 systemd 配置，然后告诉 systemd 重新启动 MySQL 服务：Whenever you create or change override.conf, reload the systemd configuration, then tell systemd to restart the MySQL service:

systemctl daemon-reload
systemctl restart mysqld  # RPM platforms
systemctl restart mysql   # Debian platforms

对于 systemd，某些参数必须使用 override.conf 配置方法，而不是 [mysqld]、[mysqld_safe] 或 [safe_mysqld] 组：With systemd, the override.conf configuration method must be used for certain parameters, rather than settings in a [mysqld], [mysqld_safe], or [safe_mysqld] group in a MySQL option file:

有关使用 systemd 而不是 mysqld_safe 的更多信息，请参阅 从 mysqld_safe 迁移到 systemd。For additional information about using systemd rather than mysqld_safe, see Migrating from mysqld_safe to systemd.

您可以在 override.conf 中设置以下参数：You can set the following parameters in override.conf:

一些 MySQL 参数是使用环境变量配置的：Some MySQL parameters are configured using environment variables:

有多个指定由 systemd 管理的 MySQL 服务器进程使用的环境变量值的方法：There are multiple ways to specify environment variable values for use by the MySQL server process managed by systemd:

要为mysqld指定选项而不直接修改 systemd 配置文件，请设置或取消设置 MYSQLD_OPTS systemd 变量。例如：To specify options for mysqld without modifying systemd configuration files directly, set or unset the MYSQLD_OPTS systemd variable. For example:

systemctl set-environment MYSQLD_OPTS="--general_log=1"
systemctl unset-environment MYSQLD_OPTS

MYSQLD_OPTS也可以在/etc/sysconfig/mysql文件中设置。MYSQLD_OPTS can also be set in the /etc/sysconfig/mysql file.

修改 systemd 环境后，重新启动服务器以使更改生效：After modifying the systemd environment, restart the server to make the changes effective:

systemctl restart mysqld  # RPM platforms
systemctl restart mysql   # Debian platforms

对于使用 systemd 的平台，如果服务器启动时数据目录为空，则会对其进行初始化。如果数据目录是暂时消失的远程挂载，这可能会出现问题：挂载点将显示为空数据目录，然后将其初始化为新的数据目录。要禁止这种自动初始化行为，请在 /etc/sysconfig/mysql 文件中指定以下行（如果该文件不存在，则创建该文件）：For platforms that use systemd, the data directory is initialized if empty at server startup. This might be a problem if the data directory is a remote mount that has temporarily disappeared: The mount point would appear to be an empty data directory, which then would be initialized as a new data directory. To suppress this automatic initialization behavior, specify the following line in the /etc/sysconfig/mysql file (create the file if it does not exist):

NO_INIT=true

本节介绍如何为多个 MySQL 实例配置 systemd。This section describes how to configure systemd for multiple instances of MySQL.

要使用多实例功能，请修改my.cnf 选项文件包含每个实例的关键选项配置。这些文件位置是典型的：To use multiple-instance capability, modify the my.cnf option file to include configuration of key options for each instance. These file locations are typical:

例如，管理两个名为 replica01 和 replica02，将类似内容添加到选项文件中：For example, to manage two instances named replica01 and replica02, add something like this to the option file:

RPM 平台：RPM platforms:

[mysqld@replica01]
datadir=/var/lib/mysql-replica01
socket=/var/lib/mysql-replica01/mysql.sock
port=3307
log-error=/var/log/mysqld-replica01.log

[mysqld@replica02]
datadir=/var/lib/mysql-replica02
socket=/var/lib/mysql-replica02/mysql.sock
port=3308
log-error=/var/log/mysqld-replica02.log

Debian 平台：Debian platforms:

[mysqld@replica01]
datadir=/var/lib/mysql-replica01
socket=/var/lib/mysql-replica01/mysql.sock
port=3307
log-error=/var/log/mysql/replica01.log

[mysqld@replica02]
datadir=/var/lib/mysql-replica02
socket=/var/lib/mysql-replica02/mysql.sock
port=3308
log-error=/var/log/mysql/replica02.log

此处显示的副本名称使用 @ 作为分隔符，因为这是 systemd 支持的唯一分隔符。The replica names shown here use @ as the delimiter because that is the only delimiter supported by systemd.

然后实例由普通 systemd 命令管理，例如 as：Instances then are managed by normal systemd commands, such as:

systemctl start mysqld@replica01
systemctl start mysqld@replica02

要使实例能够在启动时运行，请执行以下操作：To enable instances to run at boot time, do this:

systemctl enable mysqld@replica01
systemctl enable mysqld@replica02

还支持使用通配符。例如，此命令显示所有副本实例的状态：Use of wildcards is also supported. For example, this command displays the status of all replica instances:

systemctl status 'mysqld@replica*'

为了管理同一台计算机上的多个 MySQL 实例，systemd 自动使用不同的单元文件：For management of multiple MySQL instances on the same machine, systemd automatically uses a different unit file:

在单元文件中，%I 和 %i 引用 @ 标记后传入的参数，用于管理特定实例。对于如下命令：In the unit file, %I and %i reference the parameter passed in after the @ marker and are used to manage the specific instance. For a command such as this:

systemctl start mysqld@replica01

systemd 使用如下命令启动服务器：systemd starts the server using a command such as this:

mysqld --defaults-group-suffix=@%I ...

结果是读取 [server]、[mysqld] 和 [mysqld@replica01] 选项组并将其用于该服务实例。The result is that the [server], [mysqld], and [mysqld@replica01] option groups are read and used for that instance of the service.

因为 mysqld_safe 未安装在使用 systemd 管理 MySQL 的平台上，之前为该程序指定的选项（例如，在 [mysqld_safe] 或 [safe_mysqld] 选项组中）必须以其他方式指定：Because mysqld_safe is not installed on platforms that use systemd to manage MySQL, options previously specified for that program (for example, in an [mysqld_safe] or [safe_mysqld] option group) must be specified another way: