MySQL 'random' shutdowns since Zabbix installed

[slydog]

Hello,

A couple weeks ago I installed Zabbix 2.2.6 server on a RHEL 6.2 (x86_64) host. The particular server runs MySQL 5.1 on it, and has had very active MySQL databases running on it for more than a year without any problems at all.

Since I installed Zabbix using packages and following the Zabbix.com installation instructions at .../documentation/2.2/manual/installation/install_from_packages we have had 3 or 4 unexpected shutdowns of MySQL. According to the mysqld.log a shutdown command has been issued at the time of each outage. A couple days ago the log showed

141218 20:46:51 [Note] /usr/libexec/mysqld: Normal shutdown

141218 20:46:51 [Note] Event Scheduler: Purging the queue. 0 events
141218 20:46:53  InnoDB: Starting shutdown...
141218 20:46:55  InnoDB: Shutdown completed; log sequence number 0 93867942
141218 20:46:55 [Note] /usr/libexec/mysqld: Shutdown complete

141218 20:46:55 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended

I have examined all the possible cronjobs on the server; and have examined the EVENTS tables in MySQL; but have found nothing that indicates where this shutdown command is originating. I have also been able to find any evidence of someone issuing a shutdown command while logged into the host.

Any help figuring this out will be much appreciated!

[slydog]

Is it possible that one of these php configuration settings could be triggering the MySQL shutdown command?:

php_value max_execution_time 300
php_value max_input_time 300

They are added to

/etc/httpd/conf.d/zabbix.conf

as part of the installation.