Calculated Item

[navtek007]

Is it possible to create an item based. Eg i would like to find the percent memory usage of my windows server eg:

memory[free] / memory[total]

Is this possible?

[Alexei]

Yes, it is possible and supported.

[navtek007]

any reason why mine isn't working then? have i got the syntax correct?

[themons]

is anybody will be able to do this ?

[Clansman]

I've just tried it and it doesn't work here either.
It seems to pick up only the first part of the expression - in this case system.swap.size[,total]-system.swap.size[,free] or system.swap.size[,total] - system.swap.size[,free].

Puzzled...

Cheers,
Pedro Venda.

[themons]

yes i also have the problem. and in try different form of expression with {} () and [] nothing different or errors append when i want to save the item.

[emx]

Alexei, could you elaborate on your answer?

After a few hours reading the documention and the forums, I couldn't find a way to have "calculated" items.

I have two stats ("success" and "total") and I want to calculate their ration.

I have tried every possible syntax with "(" and "{" such as

({vm.stats[success]}/{vm.stats[total]})

Also tried the "trigger" syntax to no avail.

Of course vm.stats[aa] and vm.stats[bb] work well (they are UserParameter I defined in my zabbix_agentd.conf).

A couple of people have asked about this on the forum. Last year, Alexei answered "Yes, it is possible and supported." however he did not provide any example of the syntax nor did he answer the few follow-up posts that complained it doesn't seem to work...

Anyone knows how to "calculate" an item based on other items?

Thanks for any hints...

[Alexei]

There are no calculated items in ZABBIX. The functionality hasn't been implemented and I do know if it ever be.

[emx]

Thanks for this answer. At least I can stop trying now

This could be an interesting feature. In my context I get VoIP measurements through an external UserParameter item, e.g. Total SIP calls and Total Successful SIP calls. The ratio provides an important measure of quality. I can imagine a few other use of calculated fields.

Since you have written a parser for triggers, it shouldn't be hard to use it for items? That's my wild, uneducated and probably stupid guess.

Thanks anyway for the great work on Zabbix, I love it more every day.

[Alexei]

Since you have written a parser for triggers, it shouldn't be hard to use it for items? That's my wild, uneducated and probably stupid guess.

I do not see any technical problems to have this feature implemented and it possibly will be done if this fits nicely into design of 1.4.

[emx]

Great news!

Thanks Alexei for considering this feature. In fact, I was about to contact you to volunteer producing a patch.

[testos]

Greetings,

For obtaining percentage of available total memory i'm trying this item: vm.memory.size[free]) / vm.memory.size[total] * 100

zabbix doesn't complain but it gives back somewhat strange result same 8.89 M%.

User defined calculated items are more comfortable than to do it in triggers. Are they allowed now in the 1.4?

Regards.

[Alexei]

No, calculated items are not supported by 1.4.x.

[jshuler]

So, how would a person get percent memory used?

[testos]

Synthetic calculated items

As a workaround you may use synthetic calculated items (this is a work for the zabbix_agentd's userparameter).

a) For get percent memory used:
UserParameter=Memoria.PorcentajeUsada,echo "$((100-(`/usr/bin/zabbix_get -s 127.0.0.1 -k vm.memory.size[free]`*100/`/usr/bin/zabbix_get -s 127.0.0.1 -k vm.memory.size[total]`)))"

b) For get percent memory free:
UserParameter=Memoria.PorcentajeLibre,echo "$((`/usr/bin/zabbix_get -s 127.0.0.1 -k vm.memory.size[free]`*100/`/usr/bin/zabbix_get -s 127.0.0.1 -k vm.memory.size[total]`))"