Zabbix Server is not connecting to mysql database, and sometimes it's not starting normally.
Please check the below log file and screenshot for reference.

[root@nuem_cacti_nms sbin]# tailf /tmp/zabbix_server.log
2273:20170101:102508.740 Jabber notifications: NO
2273:20170101:102508.740 Ez Texting notifications: YES
2273:20170101:102508.740 ODBC: NO
2273:20170101:102508.740 SSH2 support: NO
2273:20170101:102508.740 IPv6 support: NO
2273:20170101:102508.740 TLS support: NO
2273:20170101:102508.740 ******************************
2273:20170101:102508.740 using configuration file: /root/zabbix_tool/zabbix-server/etc/zabbix_server.conf
zabbix_server [2273]: cannot create IPC key for path [/root/zabbix_tool/zabbix-server/etc/zabbix_server.conf] id [h]: [13] Permission denied