To monitor a folder on a mount point

Steps to reproduce:

1. Item = vfs.dir.size[/mnt/*****_****/***] , directory size is ~ 8-10 TB
2. I have tried vfs.dir.size modes (default & 0)
3. Time out setting in zabbix agent/server/proxy configuration is 30 (max)

Result:

getting following error: Timeout while waiting for data

Expected:

Requirement:

To monitor directory size of ~ 8-10 TB, please have a look into it. So that I could setup zabbix monitoring of our production env. Thanks

P.S: Monitoring of 14TB mount point is in place, using filesystem discovery. But the required directory (same filesystem) on that mount point is neither getting discovered nor being monitored using vfs.dir.size