Steps to reproduce:

1. Discover disk C: on Windows host by Windows physical disks by Zabbix template
2. Shutdown Windows host and wait 15 minutes
3. Start Windows host so there is a big load on the disk during startup

Result:

Observe problem "C:: Disk is overloaded (util > 95% for 15m)"

Expected:

This problem must only occurs if the host actually experienced high disk load during 15 minutes in a row, not 1 min during startup.

The trigger prototype is:

min(/Windows physical disks by Zabbix agent/perf_counter_en["\PhysicalDisk({#DEVNAME})\% Idle Time",60],15m)>{$VFS.DEV.UTIL.MAX.WARN} 

min() doesn't care how many samples of data there are within 15 given period as long as there is just one sample.