Create calculated item based on multiple values

[xmmm]

All,

I have 2 items collecting decimal data every minute. I am looking to create a calculated item to keep result of a calculation:

(item1.last_value - item1.prev_value) / (item2.last_value - item2.prev_value)

Or: item1.change() - item2.change()

I searched several previous posts and tested many combinations but cannot make it work.

Can someone please share?

Thank you.

[ingus.vilnis]

Hello and welcome!

Please take a look at Zabbix documentation here: https://www.zabbix.com/documentation...pes/calculated
There you may find useful information on calculated items and get yours to work.

Best Regards,
Ingus

[xmmm]

I read the doc but it does not clearly describe why below usage is not accepted

(last("key1",0)-last("key1",1))/(last("key2",0)-last("key2",1))

As I tested, it seems that below syntax is accepted.
last("key1",0)-last("key1",1)

Any suggestions? Thank you.

[aib]

silly notes : try to add spaces around "/"
like

(last("key1",0)-last("key1",1))[U] / [/U](last("key2",0)-last("key2",1))

[karmukis]

Use external checks for calculated Items

Hi,
I know you asked for a different thing, but I was wondering, is it possible to create and "calculated item", using and external check???

Because, in normal checks the "key" is just a name, but, in the external check, is becomes a formula....

So... we try to create a calculated item and it didn't work... error: "can not evaluate function"

Any help will be more than appreciated.

thanks so much.

karina costa

[ingus.vilnis]

Hi Karina,

This is a complicated question with no real examples provided.
Here are some directions I could point you to:

• Data type of the original external scripts (text vs numreic) do not match
• The returned data is not a number or contains some extra characters or something
• Division by zero
• Typo in the calculated formula itself
• You modified the key of external check but did not update the calculated formula manually

https://www.zabbix.com/documentation/2.2/manual/config/items/itemtypes/calculated

Hard to tell really. If you like, you can share a bit more detailed information about the actual item configurations (screenshots and item keys as text) so we can have a look and see if anybody has some ideas.

Best Regards,
Ingus

[karmukis]

Hi Ingus,
thanks you for the answer, I´ll check the data and what I manage to do, be back with the results in some days.
thanks!!

karina

[emmanux]

I read the doc but it does not clearly describe why below usage is not accepted

(last("key1",0)-last("key1",1))/(last("key2",0)-last("key2",1))

As I tested, it seems that below syntax is accepted.
last("key1",0)-last("key1",1)

Any suggestions? Thank you.

Did you tried inverting the terms?

(last("key2",0)-last("key2",1))/(last("key1",0)-last("key1",1))

Can you provide a real example?