# Configuring MariaDB for systemd This page covers configuration for MariaDB running under [systemd](/docs/server/server-management/starting-and-stopping-mariadb/systemd.md). For starting, stopping, and inspecting the service, see [Starting MariaDB on systemd](/docs/server/server-management/starting-and-stopping-mariadb/systemd/starting.md). {% hint style="info" %} The per-option sections on this page apply to **installed-service deployments** — MariaDB started via `mariadb.service`. If you are a developer running `mariadbd` from a build directory (for example, running `mysql-test-run`), most of those settings don't apply, because your workflow doesn't go through `mariadb.service`. See [Configuring systemd for MariaDB Development](#configuring-systemd-for-mariadb-development) below for a one-shot setup script that covers the developer case. {% endhint %} ## Configuring systemd for MariaDB Development When developing MariaDB, you typically run `mariadbd` directly from a build directory rather than installing it as a service. In that case, the per-service drop-in files described below (under `/etc/systemd/system/mariadb.service.d/`) have no effect, because no `mariadb.service` is involved. Instead, the limits need to be set in `systemd`'s system-wide manager configuration (`/etc/systemd/system.conf.d/`), `sysctl`, and PAM. The following script applies the settings that are typically needed to run `mariadbd` and `mysql-test-run` (`mtr`) on a developer workstation, including support for `io_uring` asynchronous I/O in InnoDB, a sufficient number of open files, large core dumps, the `aio` limit fix for `mtr`, predictable core file locations, and `perf` / `rr` access. Run it as root: ```bash #!/bin/bash # # Fixes needed for openSUSE (systemd) to be able to run and develop MariaDB # without having to install it as a service # This script needs to be run as root set -e # ── systemd limits ──────────────────────────────────────────────────────────── mkdir -p /etc/systemd/system.conf.d cat > /etc/systemd/system.conf.d/memlock.conf << 'EOF' # Needed for io_uring asynchronous IO used by InnoDB [Manager] DefaultLimitMEMLOCK=infinity EOF cat > /etc/systemd/system.conf.d/nofile.conf << 'EOF' # Databases need a lot of open files [Manager] DefaultLimitNOFILE=65535 EOF cat > /etc/systemd/system.conf.d/bigcore.conf << 'EOF' # Allow big cores (needed to be able to debug MariaDB core files) [Manager] LimitCORE=infinity EOF # Apply systemd changes systemctl daemon-reexec # ── sysctl ──────────────────────────────────────────────────────────────────── mkdir -p /etc/sysctl.d cat > /etc/sysctl.d/50-aio.conf << 'EOF' # Fix "io_setup(1024) returned Unknown error -11 when running mtr tests" fs.aio-max-nr=1048576 EOF cat > /etc/sysctl.d/50-coredump.conf << 'EOF' # Store core files in the current directory kernel.core_pattern=core.%p EOF cat > /etc/sysctl.d/50-perf_event_paranoid.conf << 'EOF' # Allow usage of perf/RR kernel.perf_event_paranoid=1 EOF # Apply sysctl changes sysctl --system # ── PAM limits ──────────────────────────────────────────────────────────────── mkdir -p /etc/security/limits.d cat > /etc/security/limits.d/nofile.conf << 'EOF' # Takes effect on next login * soft nofile 65535 * hard nofile 65535 root soft nofile 65535 root hard nofile 65535 EOF echo "" echo "Done. PAM (number of open files) limits (/etc/security/limits.d/nofile.conf) will take effect on next login." ``` {% hint style="warning" %} The PAM limit change in `/etc/security/limits.d/nofile.conf` only takes effect on your next login. Log out and back in (or open a new shell session) before running `mtr`. {% endhint %} ## Configuring the Systemd Service You can configure MariaDB's `systemd` service by creating a "drop-in" configuration file for the `systemd` service. On most systems, the `systemd` service's directory for "drop-in" configuration files is `/etc/systemd/system/mariadb.service.d/`. You can confirm the directory and see what "drop-in" configuration files are currently loaded by executing: ```bash $ sudo systemctl status mariadb.service ● mariadb.service - MariaDB 10.1.37 database server Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: disabled) Drop-In: /etc/systemd/system/mariadb.service.d └─migrated-from-my.cnf-settings.conf, timeoutstartsec.conf ... ``` If you want to configure the `systemd` service, you can create a file with the `.conf` extension in that directory. The configuration options you would like to change need to be placed in an appropriate section within the file, usually `[Service]`. If a `systemd` option is a list, you may need to set the option to empty before you set the replacement values: ```ini [Service] ExecStart= ExecStart=/usr/bin/numactl --interleave=all /usr/sbin/mariadbd $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION ``` After any configuration change, you need to execute the following for the change to take effect: ```bash sudo systemctl daemon-reload ``` ### Useful Systemd Options Useful `systemd` options are listed below. If an option is equivalent to a common [mariadbd-safe](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md) option, then that is also listed. Use `systemctl edit mariadb.service` to create the systemd option under a `[Service]` section header. | mariadbd-safe option | systemd option | Comments | | --------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | no option | [ProtectHome=false](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#ProtectHome=) | If any MariaDB files are in `/home/` | | no option | [PrivateDevices=false](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#PrivateDevices=) | If any MariaDB storage references raw block devices | | no option | [ProtectSystem=](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#ProtectSystem=) | If any MariaDB write any files to anywhere under `/boot`, `/usr` or `/etc` | | no option | [TimeoutStartSec={time}](https://www.freedesktop.org/software/systemd/man/systemd.service.html#TimeoutStartSec=) | Service startup timeout. See [Configuring the Systemd Service Timeout](#configuring-the-systemd-service-timeout). | | no option (see [MDEV-9264](https://jira.mariadb.org/browse/MDEV-9264)) | [OOMScoreAdjust={priority}](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#OOMScoreAdjust=) | For instance, `-600` to lower priority of OOM killer for `mariadbd` | | [open-files-limit](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [LimitNOFILE={limit}](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=) | Limit on number of open files. See [Configuring the Open Files Limit](#configuring-the-open-files-limit). | | [core-file-size](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [LimitCORE={size}](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=) | Limit on core file size. Useful when enabling core dumps. See [Configuring the Core File Size](#configuring-the-core-file-size). | | | [LimitMEMLOCK={size}](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=) or infinity | Limit on how much can be locked in memory. Useful when [large-pages](/docs/server/server-management/variables-and-modes/server-system-variables.md#large_pages) or [memlock](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-options.md#-memlock) is used | | [nice](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [Nice={nice value}](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#Nice=) | | | [syslog](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [StandardOutput=syslog](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#StandardOutput=) | See [Configuring MariaDB to Write the Error Log to Syslog](#configuring-mariadb-to-write-the-error-log-to-syslog). | | | [StandardError=syslog](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#StandardError=) | | | | [SyslogFacility=daemon](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#SyslogFacility=) | | | | [SyslogLevel=err](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#SyslogLevel=) | | | [syslog-tag](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [SyslogIdentifier](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#SyslogIdentifier=) | | | [flush-caches](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | ExecStartPre=/usr/bin/sync | | | | ExecStartPre=/usr/sbin/sysctl -q -w vm.drop\_caches=3 | | | [malloc-lib](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [Environment=LD\_PRELOAD=/path/to/library](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#Environment=) | | | [numa-interleave](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | [NUMAPolicy=interleave](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#NUMAPolicy=) | from systemd v243 onwards | | | or: ExecStart=/usr/bin/numactl --interleave=all /usr/sbin/mariadbd $MYSQLD\_OPTS $\_WSREP\_NEW\_CLUSTER $\_WSREP\_START\_POSITION | prepending ExecStart=/usr/bin/numactl --interleave=all to existing ExecStart setting | | [no-auto-restart](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#options) | Restart={exit-status} | | {% hint style="info" %} The [systemd](https://www.freedesktop.org/software/systemd/man/systemd.service.html) manual contains the official meanings for these options. The manual also lists considerably more options than the ones listed above. {% endhint %} There are other options and the `mariadb-service-convert` script attempts to convert these as accurately as possible. ### Configuring the Systemd Service Timeout MariaDB's [systemd](/docs/server/server-management/starting-and-stopping-mariadb/systemd.md) unit file has a default startup timeout of about 90 seconds on most systems. If a service startup takes longer than this default startup timeout, then `systemd` assumes that `mariadbd` has failed to startup, which causes `systemd` to kill the `mariadbd` process. To work around this, it can be changed by configuring the [TimeoutStartSec](https://www.freedesktop.org/software/systemd/man/systemd.service.html#TimeoutStartSec=) option for the `systemd` service. A similar problem can happen when stopping the MariaDB service. Therefore, it may also be a good idea to set [TimeoutStopSec](https://www.freedesktop.org/software/systemd/man/systemd.service.html#TimeoutStopSec=). For example, you can reconfigure the MariaDB `systemd` service to have an infinite timeout by executing one of the following commands: If you are using `systemd` 228 or older, then you can execute the following to set an infinite timeout: ```bash sudo systemctl edit mariadb.service [Service] TimeoutStartSec=0 TimeoutStopSec=0 ``` [Systemd 229 added the infinity option](https://lists.freedesktop.org/archives/systemd-devel/2016-February/035748.html), so if you are using `systemd` 229 or later, you can execute the following to set an infinite timeout: ```bash sudo systemctl edit mariadb.service [Service] TimeoutStartSec=infinity TimeoutStopSec=infinity ``` Note that [systemd 236 added the EXTEND\_TIMEOUT\_USEC environment variable](https://lists.freedesktop.org/archives/systemd-devel/2017-December/039996.html) that allows services to extend the startup timeout during long-running processes. On systems with systemd versions that support it, MariaDB uses this feature to extend the startup timeout during certain startup processes that can run long. ### Configuring the Open Files Limit When using `systemd`, rather than setting the open files limit by setting the [open-files-limit](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#mariadbd-safe-options) option for `mariadbd-safe` or the [open\_files\_limit](/docs/server/server-management/variables-and-modes/server-system-variables.md#open_files_limit) system variable, the limit can be changed by configuring the [LimitNOFILE](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=) option for the MariaDB `systemd` service. The default is set to `LimitNOFILE=16364` in `mariadb.service`. For example, you can reconfigure the MariaDB `systemd` service to have a larger limit for open files by executing the following commands: ```bash sudo systemctl edit mariadb.service [Service] LimitNOFILE=infinity ``` {% hint style="info" %} Setting `LimitNOFILE=infinity` doesn't actually set the open file limit to *infinite*. {% endhint %} In `systemd` 234 and later, setting `LimitNOFILE=infinity` actually sets the open file limit to the value of the kernel's `fs.nr_open` parameter. Therefore, in these `systemd` versions, you may have to change this parameter's value. The value of the `fs.nr_open` parameter can be changed permanently by setting the value in [/etc/sysctl.conf](https://linux.die.net/man/5/sysctl.conf) and restarting the server. The value of the `fs.nr_open` parameter can be changed temporarily by executing the [sysctl](https://linux.die.net/man/8/sysctl) utility: ```bash sudo sysctl -w fs.nr_open=1048576‬ ``` In `systemd` 233 and before, setting `LimitNOFILE=infinity` actually sets the open file limit to `65536`. See [systemd issue #6559](https://github.com/systemd/systemd/issues/6559) for more information. Therefore, in these `systemd` versions, it is not generally recommended to set `LimitNOFILE=infinity`. Instead, it is generally better to set `LimitNOFILE` to a very large integer. For example: ```bash sudo systemctl edit mariadb.service [Service] LimitNOFILE=1048576 ``` ### Configuring the Core File Size When using `systemd`, if you would like to enable core dumps, rather than setting the core file size by setting the [core-file-size](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#mariadbd-safe-options) option for `mariadbd-safe`, the limit can be changed by configuring the [LimitCORE](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=) option for the MariaDB `systemd` service. For example, you can reconfigure the MariaDB `systemd` service to have an infinite size for core files by executing the following commands: ```bash sudo systemctl edit mariadb.service [Service] LimitCORE=infinity ``` ### Configuring MariaDB to Write the Error Log to Syslog When using `systemd`, if you would like to redirect the [error log](/docs/server/server-management/server-monitoring-logs/error-log.md) to the [syslog](https://linux.die.net/man/8/rsyslogd), then that can easily be done by doing the following: * Ensure that [log\_error](/docs/server/server-management/variables-and-modes/server-system-variables.md#log_error) system variable is not set. * Set [StandardOutput=syslog](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#StandardOutput=). * Set [StandardError=syslog](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#StandardError=). * Set [SyslogFacility=daemon](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#SyslogFacility=). * Set [SysLogLevel=err](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#SyslogLevel=). For example: ```bash sudo systemctl edit mariadb.service [Service] StandardOutput=syslog StandardError=syslog SyslogFacility=daemon SysLogLevel=err ``` If you have multiple instances of MariaDB, then you may also want to set [SyslogIdentifier](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#SyslogIdentifier=) with a different tag for each instance. ### Configuring LimitMEMLOCK #### Configuring Support for io\_uring Asynchronous IO in InnoDB If using [`--memlock`](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-options.md#-memlock), or the `io_uring` `asynchronous` IO in InnoDB in MariaDB 10.6 or above, with a Linux Kernel version < 5.12, you need to raise the `LimitMEMLOCK` limit. ```bash sudo systemctl edit mariadb.service [Service] LimitMEMLOCK=2M ``` #### Increasing the Limit for aio When running the server with lots of users, the default `aio` value is too small. When running `mysql-test-run`, you could see an error like this: {% code overflow="wrap" %} ``` io_setup(1024) returned Unknown error -11 ``` {% endcode %} The fix is to configure a higher aio value: 1. Create this file: `/etc/sysctl.d/50-aio.conf` 2. Add the following to that file: {% code overflow="wrap" %} ```ini # Fix "io_setup(1024) returned Unknown error -11 when running mtr tests" fs.aio-max-nr=1048576 ``` {% endcode %} ### Configuring Access to Home Directories MariaDB's [systemd](/docs/server/server-management/starting-and-stopping-mariadb/systemd.md) unit file restricts access to `/home`, `/root`, and `/run/user` by default. This restriction can be overridden by setting the [ProtectHome](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#ProtectHome=) option to `false` for the MariaDB `systemd` service. This is done by creating a "drop-in" directory `/etc/systemd/system/mariadb.service.d/` and in it a file with a `.conf` suffix that contains the `ProtectHome=false` directive. You can reconfigure the MariaDB `systemd` service to allow access to `/home` by executing the following commands: ```bash sudo systemctl edit mariadb.service [Service] ProtectHome=false ``` ### Configuring the umask When using `systemd`, the default file permissions of `mariadbd` can be set by setting the `UMASK` and `UMASK_DIR` environment variables for the `systemd` service. For example, you can configure the MariaDB `systemd` service's umask by executing the following commands: ```bash sudo systemctl edit mariadb.service [Service] Environment="UMASK=0750" Environment="UMASK_DIR=0750" ``` These environment variables do not set the umask. They set the default file system permissions. See [MDEV-23058](https://jira.mariadb.org/browse/MDEV-23058) for more information. Keep in mind that configuring the umask this way only affects the permissions of files created by the `mariadbd` process that is managed by `systemd`. The permissions of files created by components that are not managed by `systemd`, such as [mariadb-install-db](/docs/server/clients-and-utilities/deployment-tools/mariadb-install-db.md), are not affected. See [Specifying Permissions for Schema (Data) Directories and Tables](/docs/server/server-management/starting-and-stopping-mariadb/specifying-permissions-for-schema-data-directories-and-tables.md) for more information. ### Configuring the Data Directory When doing a standard binary tarball installation, the *datadir* is under `/usr/local/data`. However, the default `systemd` service file makes the whole `/usr` directory tree write protected. When just copying the distributed service file a tarball install does not start up, complaining for instance about this: ``` [Warning] Can't create test file /usr/local/.../data/ubuntu-focal.lower-test [ERROR] mariadbd: File '/usr/local/.../data/aria_log_control' not found (Errcode: 30 "Read-only file system") [ERROR] mariadbd: Got error 'Can't open file' when trying to use aria control file '/usr/local/.../data/aria_log_control' ``` So when using a data directory under `/usr/local` that specific directory needs to be made writable for the service using the `ReadWritePaths` setting: ```bash sudo systemctl edit mariadb.service [Service] ReadWritePaths=/usr/local/mysql/data ``` ## Systemd Socket Activation {% hint style="info" %} Systemd socket activation is available from MariaDB 10.6. {% endhint %} MariaDB can use systemd's socket activation. This is an on-demand service for MariaDB that activates when required. Systemd socket activation uses a `mariadb.socket` definition file to define a set of UNIX and TCP sockets. Systemd listens on these sockets, and when they are connected to, systemd starts the `mariadb.service` and hand over the socket file descriptors for MariaDB to process the connection. MariaDB remains running at this point, and has all sockets available and process connections exactly like it did before 10.6. When MariaDB is shut down, the systemd `mariadb.socket` remains active, and a new connection restarts the `mariadb.service`. ### Using Systemd Socket Activation To use MariaDB systemd socket activation, instead of enabling/starting `mariadb.service`, `mariadb.socket` is used instead. So the following commands work exactly like the `mariadb.service` equivalents. ```bash systemctl start mariadb.socket systemctl enable mariadb.socket ``` These files alone only contain the UNIX and TCP sockets and basic network connection information to which the server is listening for connections. `@mariadb` is a UNIX abstract socket, which means it doesn't appear on the filesystem. Connectors based on MariaDB Connector/C is able to connect with these by using the socket name directly, provided the higher level implementation doesn't try to test for the file's existence first. Some connectors like PHP use `mysqlnd` that is a pure PHP implementation and as such are only able to connect to on filesystem UNIX sockets. With systemd activated sockets there is only a file descriptor limit on the number of listening sockets that can be created. ### When to Use Systemd Socket Activation A common use case for systemd socket activated MariaDB is when there needs to be a quick boot up time. MariaDB needs to be ready to run, but it doesn't need to be running. The ideal use case for systemd socket activation for MariaDB is for infrastructure providers running many multiple instances of MariaDB, where each instance is dedicated for a user. ### Downsides to Using Systemd Socket Activation From the time the connection occurs, the client is going to be waiting until MariaDB has fully initialized before MariaDB can process the awaiting connection. If MariaDB was previously hard shutdown and needs to perform an extensive InnoDB rollback, then the activation time may be larger than the desired wait time of the client connection. ### Configuring Systemd Socket Activation When MariaDB is run under systemd socket activation, the usual [socket](/docs/server/server-management/variables-and-modes/server-system-variables.md#socket), [port](/docs/server/server-management/variables-and-modes/server-system-variables.md#port), and [backlog](/docs/server/server-management/variables-and-modes/server-system-variables.md#backlog) system variables are ignored, as these settings are contained within the systemd socket definition file. There is no configuration required in MariaDB to use MariaDB under socket activation. The systemd options available are from the [systemd documentation](https://www.freedesktop.org/software/systemd/man/systemd.socket.html), however [ListenStream](https://www.freedesktop.org/software/systemd/man/systemd.socket.html#ListenStream=) and [BackLog](https://www.freedesktop.org/software/systemd/man/systemd.socket.html#Backlog=) would be the most common configuration options. As MariaDB isn't creating these sockets, the sockets don't need to be created with a `mysql` user. The sockets MariaDB may end up listening to under systemd socket activation, it may have not had the privileges to create itself. Changes to the default `mariadb.socket` can be made in the same way as services, `systemctl edit mariadb.socket`, or using `/etc/systemd/system/mariadb.socket.d/someconfig.conf` files. ### Extra Port A `systemd` socket can be configured as an [extra\_port](/docs/server/ha-and-performance/optimization-and-tuning/buffers-caches-and-threads/thread-pool/thread-pool-system-status-variables.md#extra_port), by using [`[FileDescriptorName=extra]`](https://www.freedesktop.org/software/systemd/man/systemd.socket.html#FileDescriptorName=) in the `.socket` file. The `mariadb-extra.socket` file is already packaged and ready for use. ### Multi-Instance Socket Activation `mariadb@.socket` is MariaDB's packaged multi-instance definition. It creates multiple UNIX sockets based on the socket file started. Starting `mariadb@bob.socket` uses the `mariadb@.socket` definition with `%I` within the definition replaced with "bob". When something connects to a socket defined there, the `mariadb@bob.service` are started. ## Systemd Socket Activation for Hosting Service Providers A `systemd` socket activation service with multi-instance can provide an on-demand per user access to a hosting service provider's dedicated database. Here, "user" refers to the customer of the hosting service provider. ### End User Benefits This provides the following benefits for the user: * Each user has their own dedicated instance with the following benefits: * The instance is free from the database contention of neighbors on MariaDB shared resources (table cache, connections, etc) * The user is free to change their own configuration of MariaDB, within the limits and permissions of the service provider. * Database service level backups, like mariadb-backup, are now directly available. * A user can install their own plugins. * The user can run a different database version to their neighbors. * If a user's neighbor triggers a fault in the server, the uder's instance isn't affected. * The database runs as their unix user in the server facilitating: * User can directly migrate their MariaDB data directory to a different provider. * The user's data is protected from other users on a kernel level. ### Hosting Service Provider Benefits In addition to providing user benefits as a sales item, the following are additional benefits for the hosting service provider compared to a monolith service: * Without passwords for the database, while still having security, support may be easier. * When a user's database isn't active, there is no resource usage, only listening file descriptors by systemd. * The socket activation transparently, with a minor startup time, starts the service as required. * When the user's database hasn't had any activity after a time, it deactivates ([MDEV-25282](https://jira.mariadb.org/browse/MDEV-25282)). * Planned enhancements in InnoDB provide: * an on-demand consumption of memory ([MDEV-25340](https://jira.mariadb.org/browse/MDEV-25340) . * a proactive reduction in memory ([MDEV-25341](https://jira.mariadb.org/browse/MDEV-25341)). * a memory resource pressure reduction in memory use ([MDEV-24670](https://jira.mariadb.org/browse/MDEV-24670)). * The service provider can still cap the user's database memory usage in a ulimit way that a user cannot override in settings. * The service provider may choose a CPU/memory/IO based billing to the user on Linux `cgroup` accounting rather than the available comprared to the rather limited options in [CREATE USER](/docs/server/reference/sql-statements/account-management-sql-statements/create-user.md). * Because a user's database shuts down when inactive, a database upgrade on the server does not take effect for the user until it passively shuts down, restarts, and then gets reactivated hence reducing user downtime.. ### Downsides to the Hosting Service Provider The extra memory used by more instances. This is mitigated by the on-demand activation. The deactivation when idle, and improved InnoDB memory management. With plenty of medium size database servers running, the Linux OOM kill has the opportunity to kill off only a small number of database servers running rather than everyones. ### Configuration Items for a Per-User systemd Socket-Activitated Multi-Instance Service From a server perspective the operation are as follows. To make the socket ready to connect and systemd listening to the socket, run these commands: ```bash # systemctl start mariadb@username.socket # systemctl start mariadb-extra@username.socket ``` To enable this on reboot (the same way as a `systemd` service): ```bash # systemctl enable mariadb@username.socket # systemctl enable mariadb-extra@username.socket ``` #### A MariaDB Template File A global template file. Once installed as a user's `$HOME/.my.cnf` file, it becomes the default for many applications and for the MariaDB server itself. ```bash # cat /etc/my.cnf.templ [client] socket=/home/USER/mariadb.sock [client-server] user=USER [mariadbd] datadir=/home/USER/mariadb-datadir ``` #### Custom Configuration for the Multi-Instance Service This extends/modifies the MariaDB multi-instance service. The features of this extension are: * It automatically creates configuration file for user applications. * It installs the database on first service start. * `auth-root-*` in [mariadb-install-db](/docs/server/clients-and-utilities/deployment-tools/mariadb-install-db.md) means that the user is their own privileged user with unix socket authentication active. This means non-that user cannot access another users service, even with access to the unix socket(s). For more information, see [unix socket authentication security](/docs/server/reference/plugins/authentication-plugins/authentication-plugin-unix-socket.md#security). * If the MariaDB version was upgraded, the upgrade changes are made automatically. * `LimitData` places a hard upper limit so the user doesn't exceed a portion of the server resources. ```bash # cat /etc/systemd/system/mariadb@.service.d/user.conf [Service] User=%I ProtectHome=false Environment=MYSQLD_MULTI_INSTANCE="--defaults-file=/home/%I/.my.cnf" ExecStartPre= ExecStartPre=/bin/sh -c "[ -f /home/%I/.my.cnf ] || sed -e \"s/USER/%I/g\" /etc/my.cnf.templ > /home/%I/.my.cnf" ExecStartPre=mkdir -p /home/%I/mariadb-datadir ExecStartPre=/usr/bin/mariadb-install-db $MYSQLD_MULTI_INSTANCE --rpm \ --auth-root-authentication-method=socket --auth-root-socket-user=%I ExecStartPost=/usr/bin/mariadb-upgrade $MYSQLD_MULTI_INSTANCE # To limit user based tuning LimitData=768M # For io_uring use by innodb on < 5.12 kernels LimitMEMLOCK=1M ``` #### Custom Configuration for the Multi-Instance Socket This extends/modifies the MariaDB socket definition to be per user. Create sockets based on the user of the instance (`%I`). Permissions are only necessary in the sense that the user can connect to them. It won't matter to the server. Access control is enforced within the server, however if the user web services are run as the user, `Mode=777` can be reduced. `@mariadb-%I` is a abstract unix socket not on the filesystem. It may help if a user is in a chroot. Not all applications can connect to abstract sockets. ```bash # cat /etc/systemd/system/mariadb@.socket.d/user.conf [Socket] SocketUser=%I SocketMode=777 ListenSteam= ListenStream=@mariadb-%I ListenStream=/home/%I/mariadb.sock ``` The extra socket provides the user the ability to access the server when all max-connections are used: ```bash # cat /etc/systemd/system/mariadb-extra@.socket.d/user.conf [Socket] SocketUser=%I SocketMode=777 ListenSteam= ListenStream=@mariadb-extra-%I ListenStream=/home/%I/mariadb-extra.sock ``` ## Converting mariadbd-safe Options to Systemd Options `mariadb-service-convert` is a script included in many MariaDB packages that is used by the package manager to convert [mariadbd-safe](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#mariadbd-safe-options) options to `systemd` options. It reads any explicit settings in the `[mariadbd-safe]` [option group](/docs/server/server-management/install-and-upgrade-mariadb/configuring-mariadb/configuring-mariadb-with-option-files.md#option-groups) from [option files](/docs/server/server-management/install-and-upgrade-mariadb/configuring-mariadb/configuring-mariadb-with-option-files.md), and its output is directed to `/etc/systemd/system/mariadb.service.d/migrated-from-my.cnf-settings.conf`. This helps to keep the configuration the same when upgrading from a version of MariaDB that does not use `systemd` to one that does. Implicitly high defaults of [open-files-limit](/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-safe.md#mariadbd-safe-options) may be missed by the conversion script and require explicit configuration. 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