MySQL/MariaDB [Warning] Could not increase number of max_open_files to more than 32768 (request: 100000)

Seeing the warning recently on a number of VMs running MySQL/MariaDB.

[Warning] Could not increase number of max_open_files to more than 32768 (request: 100000)

A MariaDB process has requested a larger amount of open files, you can verify the current limit by starting a mysql session on your server and adding on the command line:

Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 7706
Server version: 10.6.14-MariaDB-1:10.6.14+maria~ubu2204 mariadb.org binary distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> SHOW VARIABLES LIKE 'open_files_limit';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| open_files_limit | 32768 |
+------------------+-------+
1 row in set (0.002 sec)

The limit is calculated by max_connections and table_open_cache and set by the value of LimitNOFILE

LimitNOFILE=100000

Create a conf file named mdbextras.conf in /etc/systemd/system/mariadb.service.d, you can name it what you like but prepend .conf

nano /etc/systemd/system/mariadb.service.d/mdbextras.conf

Add in the file:

[Service]
LimitNOFILE=100000

Save and quit, then reload the daemon:

systemctl daemon-reload

Then restart mariadb:

systemctl restart mariadb

Job done, no more warnings.

ref & ref