Does Netmrg has any guidlines for how many treads to configure depending on the number of hosts in the installation ?
Somethink like, for each 50 hosts increase 5 treads in the xml configuration ?
tks in advance
No, there hasn't really been any easy hosts-to-threads table created. There's a couple factors you can check to see if you need to increase threads though; of course, you have to have enough resources available to do this (cpu, disk access, etc).
1) If NetMRG is stomping on itself often; check /usr/local/var/log/netmrg/runtime to see if it's taking too long; if it's approaching your limit (usually 300 seconds), you need to increase the number of threads.
2) if you just want things done quicker; if you want to run shorter polling intervals, you might want to increase your threads so things get done quicker.
Of course, this won't help you with network bottlenecks or polling slow devices. If you have this problem, you may want to look into some sort of caching method outside netmrg. We typically write other pollers that store the data in a MySQL table and pull those values from the gatherer.