Open file-related variables fail using systemd

[Ceri WIlliams]

2 settings needed to be added to the unit file for PS 5.7 on Debian Jessie to honour:

- open_files_limits
- table_open_cache
- max_connections

A server went up in production with settings that were unexpected.

Changes made to /lib/systemd/system/mysql.service:

LimitNOFILE=infinity
LimitMEMLOCK=infinity

[marki555 (marki-g)]

Don't change config files in /lib/systemd. They will be overwritten. https://dev.mysql.com/doc/refman/5.7/en/server-management-using-systemd.html

Instead create a directory /etc/systemd/system/mysql.service.d/ and put a file (for example override.conf) there with your changes:
[Service]
LimitNOFILE=32000

But it would be a good idea to have more sane defaults in the unit provided by the percona package.

BTW, mysql will complain (log a Warning) on startup if it can't set the values for open files or max_connections, so it should have been spotted before putting it in production :)

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-3466