Zabbix Sender: Send Null Data?!?

[craigmbailey]

I am currently using zabbix sender to send values to zabbix. We have a list of 16 servers in which given time some may be up or down. When there is no data to send is there a way to send a null data type to zabbix so when my aggregate monitor for averaging looks at them it does not try to average the values in with the average? I tried sending zeros and of course that would lower the true average. I do not want to have to go thru the trouble of disabling and enabling hosts as a fix for this as that would become a hassle. Any help would be much appreciated. Thanks.

[zabbix_zen]

I've had a particular scenario where I needed this so I've forced the substitution of each null value by 'NULL' keyword.
This way, when Zabbix tries to decode the value it doesn't recognize it (error is returned on the log) and thus the value isn't stored
(In Monitoring | Latest Data,
'Last check' keeps the previous timestamp for that particular item)

[craigmbailey]

I am not sure what you are exactly meaning by that. Right now when the aggregate check runs it pulls all last values no matter what the timestamp of the last value. So I was wondering if there is a way to put a Null in there using zabbix_sender since I do not have data for that server. For example:

Ping Server 1 2ms
Ping Server 2 3ms
Ping Server 3 NULL ( I have this one offline)

If I send a zero in the aggregate monitor of average response time will be off since it will see it as 5ms for 3 servers where I really want is 5ms for 2 servers. Where if there was a way to send a NULL or NO DATA from zabbix sender it would not pick up data for Server 3. I apologize if I am misunderstanding your original response but hopefully someone out there might be able to shed some light on this for me. Thanks in advance.

[zabbix_zen]

Sure.

What I meant is,
zabbix_sender sends whatever you tell him to.

So,
in your BASH/Python/Perl/whatever script where you call the command which returns those availability values you can just

if command_result == '':
 value2send = 'NULL'
else:
 value2send = command_result

where 'NULL' is a value Zabbix doesn't know the meaning of, effectively ignoring it.
You'll see the corresponding error in zabbix_server.log
This implies that on the Web interface:

the value isn't stored
(In Monitoring | Latest Data,
'Last check' keeps the previous timestamp for that particular item)