Calculate two items with values from SNMP

[ivanhansson]

I'm working on a template that is for Netgear ReadyNAS OS 4 and want to calculate the result from two items, one is getting total disk size (volumeSize) and one is getting free disk space (volumeFreeSpace). So I tried to create a new item that is doing the calculation.

Formula:
last("volumeFreeSpace")/last("volumeSize")

But when I'm running the test I get this:

• Cannot evaluate function "last()": item "Template SNMP ReadyNAS RAIDAR:volumeFreeSpace" does not exist.

My plan is to based on the results create a trigger that notify me if it exceeds e.g. 20%

I'm aware that this is an easy task but I'm just a beginner and need some help to get the basics.

[aib]

[ivanhansson]

Thanks Aleksey,

Now I get it