Help required on constructing trigger expression

[zabbixfk]

Hello,

I am trying to construct trigger expression, where i need to obtain allocated and free DHCP ip scope, and if it goes below 20% need to raise alert.Below are item names
DHCP Free

system.run["C:\\zabbix\\scripts\\dhcpscopefree.bat {#DHCPSCOPE}"]

DHCP Allocated

system.run["C:\\zabbix\\scripts\\dhcpscopeallocated.bat {#DHCPSCOPE}"]

Expression on triggerprototype:

(({dhcpScopeTemplate:system.run["C:\\zabbix\\scripts\\dhcpscopefree.bat {#DHCPSCOPE}"].last(0)} * 100)/ 
({dhcpScopeTemplate:system.run["C:\\zabbix\\scripts\\dhcpscopeallocated.bat {#DHCPSCOPE}"].last(0)}+{dhcpScopeTemplate:system.run["C:\\zabbix\\scripts\\dhcpscopefree.bat {#DHCPSCOPE}"].last(0)}))<20

Any pointers are greatly helpful.

Thans

[jan.garaj]

You don't need to include percentage calculation there:

total*0.8<used

Right site must be constant so equivalent version

used/total>0.8

In your case total is (DHCP Free + DHCP Allocated), used is DHCP Allocated:

DHCP Allocated/(DHCP Free + DHCP Allocated)>0.8

What is IMHO equivalent of your trigger expression:

DHCP Free*100/(DHCP Allocated + DHCP Free)<20

Because:

free*100/total<20

Equivalent:

free/total<0.2

Equivalent:

free<0.2*total

Equivalent:

total*0.8<used

So where is the problem?