[ZBXNEXT-615] Problem in Calculated items if correspond items are not fetch Created: 2011 Jan 09  Updated: 2012 Oct 21

Status: Open
Project: ZABBIX FEATURE REQUESTS
Component/s: Server (S)
Affects Version/s: 1.8.3
Fix Version/s: None

Type: Change Request Priority: Major
Reporter: nima Assignee: Unassigned
Resolution: Unresolved Votes: 13
Labels: calculateditems
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified


 Description   

Hi
In order to check CPU usage on every core, I have created Calculated Item with Forlmula "100-last("system.cpu.util[0,idle,avg1]")" . this is good, but if in period of time zabbix server can not get system.cpu.util[0,idle,avg1] item, the calculated item will be same value until new value is fetched for system.cpu.util[0,idle,avg1], so all calculated items are not true. and related graphs display one line in graph .
if one item is not fetch,correspond calculated items are not calculated. I think this behavior is not true and reasonable.
Anyhow calculated items are important part of monitoring system.

Thanks for any suggestion.



 Comments   
Comment by richlv [ 2011 Jan 09 ]

but what do you suggest to do if the value is missing ?

Comment by nima [ 2011 Jan 10 ]

Hi
Thanks for your attention.
One solution that I can suggest is, "check last time update" that explain as follow:
Any item has "last" update check (clock filed in database),it means we have last time that in question "item" is updated and also any item has "interval" check, so we can check based on these tow fields if this item has been updated correctly or not.for example Item X has interval time 1 minute,and value of "last updated" (clock) is "1294666873" and current date hast "1294667180",it indicates that item has been not updated since 5 min ago.
one expression that I can suggest is :
if ( (current_time - Last_updated) > 2 (Time_interval)
error("item is not updated correctly in defined interval time") and calculated item not must calculate

In order to include tolerance in fetching item, I multiple "Time_interval" by 2

Thanks for any help or suggestion.

Comment by richlv [ 2011 Jan 10 ]

as noted by zabbix developer asaveljevs, that won't be a feasible solution - there are items that stop populating data, and it's a completely normal situation - for example, agent.ping, possibly some trapper items etc. moving to zbxnext & leaving open, maybe a feasible solution can be found in the future

Comment by nima [ 2011 Jan 10 ]

Thanks for your attention.
You can add mentioned expression only for calculated items that calculate on "passive" items.because in passive mode surely zabbix server does request that item.
Or you can add one option in configuration in calculated items as dependency(or any other name) for this situation.
Anyhow this problem causes false result specifically in graphs for calculated items.

Best Regards

Comment by richlv [ 2011 Feb 03 ]

another problem example - used memory is calculated to be the same as the total if available is not retrieved... results in totally incorrect values being inserted in the db

Comment by Fco. Javier Rial [ 2011 Feb 15 ]

another one more: basically, our network traffic come in/out from several vlan.. so the aggregated traffic is a calculated item from several vlan.. if one of our vlan is down, calculated item fails and so, zabbix inserts a zero in network traffic..

Comment by nima [ 2011 Feb 15 ]

Hi
Thanks for your comment.
If you agree with this topic,please vote that.

Thanks

Comment by Aleksandrs Saveljevs [ 2011 Mar 17 ]

Related issues: ZBXNEXT-292, ZBXNEXT-766.

Comment by Robert Foss [ 2012 Mar 16 ]

Having last() take a default parameter would solve some issues.

last(key, 0) == 0, If key is 'Not supported'

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