Zabbix server looses communication with it´s own zabbix agent

[andre.mandelli]

Hey there fellows!

I have a Zabbix server 4.4 which is showing a weird behaviour: every 38 seconds it shows the following messageon the server log:

"10672:20200913:015949.071 resuming Zabbix agent checks on host "Zabbix server": connection restored"

The agent log on debug doesn´t seem to show anything unusual. At around the same time, log messages are as follows:

16232:20200913:015947.576 In send_buffer() host:'127.0.0.1' port:10051 entries:0/150
16232:20200913:015947.576 End of send_buffer():SUCCEED
16232:20200913:015947.576 zbx_setproctitle() title:'active checks #1 [idle 1 sec]'
16225:20200913:015948.565 zbx_setproctitle() title:'collector [processing data]'
16225:20200913:015948.565 In update_cpustats()
16225:20200913:015948.565 End of update_cpustats()
16225:20200913:015948.565 zbx_setproctitle() title:'collector [idle 1 sec]'
16232:20200913:015948.577 In send_buffer() host:'127.0.0.1' port:10051 entries:0/150
16232:20200913:015948.577 End of send_buffer():SUCCEED
16232:20200913:015948.577 zbx_setproctitle() title:'active checks #1 [idle 1 sec]'
16230:20200913:015949.069 zbx_setproctitle() title:'listener #5 [processing request]'
16230:20200913:015949.069 Requested [system.cpu.util[,idle]]
16230:20200913:015949.069 Sending back [75.035311]
16230:20200913:015949.069 zbx_setproctitle() title:'listener #5 [waiting for connection]'
16231:20200913:015949.071 zbx_setproctitle() title:'listener #6 [processing request]'
16231:20200913:015949.071 Requested [net.tcp.port[172.31.0.5,53]]
16225:20200913:015949.565 zbx_setproctitle() title:'collector [processing data]'
16225:20200913:015949.565 In update_cpustats()
16225:20200913:015949.565 End of update_cpustats()
16225:20200913:015949.566 zbx_setproctitle() title:'collector [idle 1 sec]'
16229:20200913:015949.576 zbx_setproctitle() title:'listener #4 [processing request]'
16229:20200913:015949.576 Requested [net.tcp.port[10.0.10.1,22]]
16232:20200913:015949.577 In send_buffer() host:'127.0.0.1' port:10051 entries:0/150
16232:20200913:015949.577 End of send_buffer():SUCCEED
16232:20200913:015949.577 zbx_setproctitle() title:'active checks #1 [idle 1 sec]'

The zabbix server resources seem to be fine - poller busy below 60%, CPU and RAM fine as well.
I have around 67 enabled hosts, 4120 items enabled and 134 vps.

Does anyone have any ideas as to where to troubleshoot this issue or even what might be causing it?

There are in fact many data gaps regarding the Zabbix Server data collected by the MySQL template, as per graph below:




Could these issues be related?

Thanks in advance!
Andre.