Invisible filesystem

[mauro.michelotti]

Hello everyone.
I need help to understand the following problem.

I have a couple of servers at a customer's site that are under monitoring with Zabbix 3.2.
The situation is this:

Zabbix Server <- internet -> Customer site {Server1 [proxy + agent], Server2 [agent]}

That is:
- Server1 has both Zabbix agent and Zabbix proxy
- Server2 has only Zabbix agent and points to Zabbix proxy for sending data to Zabbix server.
Server1 is an Ubuntu 16, Server2 is a Centos 7.

Configuration works at 99%: I get real-time information (also for custom services defined on the agent) and configuration changes are sent from Zabbix server to both Zabbix clients.
What I DO NOT receive is the status of some filesystems on 2nd Server: I have the status of the /, /home and /boot partitions but I DO NOT receive informations about /srv filesystem (xfs).

/etc/fstab on Server2 is
/dev/mapper/ca_database0510-root           /      ext4    defaults        1 1
UUID=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx  /boot  xfs     defaults        0 0
/dev/mapper/ca_database0510-home           /home  ext4    defaults        1 2
/dev/mapper/ca_database0510-srv            /srv   xfs     defaults        0 0
/dev/mapper/ca_database0510-swap           swap   swap    defaults        0 0

With command zabbix_get

/opt/zabbix/bin/zabbix_get -s 192.168.1.105 -p 10050  -k vfs.fs.discovery

I get

{"data":[
  {"{#FSNAME}":"/","{#FSTYPE}":"rootfs"}
  ,  ....<CUT>....
  ,{"{#FSNAME}":"/","{#FSTYPE}":"ext4"}
  ,{"{#FSNAME}":"/boot","{#FSTYPE}":"xfs"}
  ,{"{#FSNAME}":"/srv","{#FSTYPE}":"xfs"}
  ,{"{#FSNAME}":"/home","{#FSTYPE}":"ext4"}
]}

Server2 is a Zabbix host with templates
Template App SSH Service, Template ICMP Ping, Template OS Linux (Template App Zabbix Agent)

What's wrong ? Why do not I get the status of all Server2 filesystems?
I do not know what other information you provide to let you know what the problem might be ...

If anyone has suggestions ....
Thanks