Configuration settings and exactly what are they used for?

[heaje]

In my quest to tune my Zabbix install I've been trying to track down documentation on what some of the configuration values in zabbix_server.conf mean, as well as EXACTLY what they're used for. I like Zabbix, but I've never been very impressed by the documentation since it lacks some real depth into what a lot of things are, how they work, and their related configuration settings. Yes, I do know that the config files have comments in them, but they aren't exactly very descriptive either. They leave some room for doubt as to what exactly the variables do.

As a result of what I mentioned above, I'm going to attempt to write up what I've learned so far here. I welcome any feedback and corrections to what I have written since my assumptions are based on experience rather than real know how into the application. Take that as your disclaimer that I could be wrong .

zabbix_server.conf:

StartPollers - The "generic" poller. This is what goes out and collects data for the following item types:

• Zabbix Agent
• External Check
• SSH Agent
• Telnet Agent
• Simple Check (Non-ICMP)

StartIPMIPollers - The IPMI poller.

• IPMI Agent

StartPingers - I believe this is only used by ICMP Simple Checks.

• Simple Check (ICMP)

StartTrappers - This is one where I have a few questions. One of the big ones is whether items collected by Proxies are sent to the Zabbix Server process using one of the trappers. I have no idea in that case. It is used by:

• Zabbix Trapper

StartJavaPollers - The number of pollers to start for JMX checks.

• JMX Agent

StartPollersUnreachable - I assume this has something to do with when Zabbix detects a particular agent as being down (not sure if JMX checks are included). Essentially, the more pollers of this type you have, the more responsive Zabbix will be when dealing with multiple unreachable agents.

StartDiscoverers - This is used by Zabbix for Discovery rules set in "Configuration"->"Discovery"

StartDBSyncers - I have no idea. I would LOVE to know what exactly a DBSyncer instance is.

<whatever>CacheSize - When do the various caches get used? I haven't seen anything that clearly explains it. I have a generic idea what they are used by from the comments in the configuration file, but there isn't anything that describes when they get used. That would be helpful to know so that I could properly tune the size of it.

[richlv]

zabbix_server.conf:

StartPollers - The "generic" poller. This is what goes out and collects data for the following item types:

• Zabbix Agent
• External Check
• SSH Agent
• Telnet Agent
• Simple Check (Non-ICMP)

also snmp items

StartTrappers - This is one where I have a few questions. One of the big ones is whether items collected by Proxies are sent to the Zabbix Server process using one of the trappers. I have no idea in that case. It is used by:

• Zabbix Trapper

also active proxies, active agents, child nodes... any incoming connection, including telnetting to that port

StartPollersUnreachable - I assume this has something to do with when Zabbix detects a particular agent as being down (not sure if JMX checks are included). Essentially, the more pollers of this type you have, the more responsive Zabbix will be when dealing with multiple unreachable agents.

StartDiscoverers - This is used by Zabbix for Discovery rules set in "Configuration"->"Discovery"

StartDBSyncers - I have no idea. I would LOVE to know what exactly a DBSyncer instance is.

<whatever>CacheSize - When do the various caches get used? I haven't seen anything that clearly explains it. I have a generic idea what they are used by from the comments in the configuration file, but there isn't anything that describes when they get used. That would be helpful to know so that I could properly tune the size of it.

unreachable pollers check hosts that are declared unreachable so that other pollers can do a good job on reachable hosts; dbsyncers calculate some triggers and put data in the database; config cache is mostly used for host & item data (also triggers in 2.0), history & historytext caches get item data stuffed in them by data collection processes, trend cache gets current trend values put in it during any given hour.

it's a bit late and we will be going over all this in zabbix training tomorrow, so sorry about the lack of verbosity

[heaje]

Thanks a lot for the reply Rich. It's nice to know I wasn't too far off . If you get a chance to be a little more verbose later (especially on the topic of what the DB syncers are and what they do), I'd love to pick your brain on some of the deeper stuff.

[richlv]

for really detailed info you'd need a zabbix devel or somebody who has dived in the code
you can also try to look at what it actually does by stracing a syncer process and looking at debuglevel4 output for one (suggested to do on a really small system, otherwise there will be lots of data).

or we can have a zabbix user meeting at some of the zabbix training places and discuss some questions... or just come over to the zabbix conference in september