Negative deltas are not stored

[nilsh]

Hi,
i have an item "testitem" which both incerease and decrease over time, and i want its delta.

i have tried it with adding a new calculated item "testitemdelta" with Formula

last("testitem")

and store as delta (simple change).

if testitem increases, testitemdelta shows its change correctly, but if testitem decreases, testitemdelta gets 0, instead of a negative value.

how can i get correct negative delta values?

[alixen]

Hi,

Hi,
i have an item "testitem" which both incerease and decrease over time, and i want its delta.

i have tried it with adding a new calculated item "testitemdelta" with Formula

last("testitem")

and store as delta (simple change).

if testitem increases, testitemdelta shows its change correctly, but if testitem decreases, testitemdelta gets 0, instead of a negative value.

how can i get correct negative delta values?

I am afraid that Zabbix will not store negative values in "delta" mode.

Maybe you could try:

last("testitem") - prev("testitem")

Make sure to use "Numeric (float)" as item type.

Regards,
Alixen

[nilsh]

Thx alixen, that works

[nilsh]

...almost.

Now i've got some timing issues, the "testitem" value is updated in short intervals, but i need the "testitemdelta" value in much longer intervals. So last and prev values temporally too close together and when the delta is updated, it takes the shorter update interval of "testitem" to get its value, instead of the value of "testitem" the "testitemdelta"'s interval ago

[alixen]

Hi,

...almost.

Now i've got some timing issues, the "testitem" value is updated in short intervals, but i need the "testitemdelta" value in much longer intervals. So last and prev values temporally too close together and when the delta is updated, it takes the shorter update interval of "testitem" to get its value, instead of the value of "testitem" the "testitemdelta"'s interval ago

You could use timeshift option of last() function:
last("testitem") - last("testitem",0,600)
will calculate delta for a 5 mn (600 s) interval.

Check the manual for details

Regards,
Alixen

[nilsh]

Yes that's what i was looking for, thanks