Frontend slow and Latest Data not always working after 4.0.5 upgrade

[vlam]

Hi

After updating our environment to version 4.0.5, the Dashboard feels very slow and also when selecting hosts in Latest Data, some works fine while the others reset on the 30s page refresh interval. What can it be and where can I look to fix it?

Thanks

[kloczek]

How much memory you have on the box with DB backend and what is the type of OS and the DB engine?

[vlam]

App server is 4x cpu with 8gb of ram
Db server is 32x cpu with 96gb of ram and all ssd
web servers is 4x cpu with 8gb ram each, 2x web servers running nginx and php-fpm

OS on all servers are running latest CentOS 7.5

We were on Zabbix 3.2.11 and there all was fine. On db sid utilization is avg 86gb ram and avg 25% cpu utilization witha load of 2-4
Db is running MySQL

what is really strange is when selecting some hosts or some host groups works fine were as selecting other hosts does not work at all, but only in Latest Data. On graphs and screens those hosts that does not work in Latest Data works 100%

[kloczek]

Do you have at least history* tables partitioned?

[vlam]

Hi

yes all tables are partitioned and also configured for monthly re-partitioning