external checks use ssh

[dagun]

Resulently, i use external checks with ssh to get the remote host's informations.but sometimes i get the nothing .
zabbix_server.log:..../checkLlinux returned nothing.
The zabbix manual says that" Do not overuse external checks! It can decrease performance for ZABBIX system very much"
Who can tell me?If I use too much external checks, what will happen????

[sanshao]

First of all you should tell and show us how your external command looks like. Than set debug level of the appropriate client agent higher and get us what you see in there.
So we might be able to help you.