Hi @usermk,
this error mostly happens, when your agent or SNMP request plus parsing the result needs more than 120 seconds to complete. This is mainly seen on devices with a huge quantity of services or really long snmpwalks like stacked core switches, hosts providing a lot of piggy back data or special agents fetching massive data.
There a several rules and settings you can adjust to come around this problem depending on the checkmk version and edition you are running.
global settings:
rules:
You can run the command cmk -II -nvv <hostname> to see, where the time is spent.
Explaination:
-I, --discover Make Check_MK behave as monitoring plugins that checks if an
inventory would find new or vanished services for the host. If configured to
do so, this will queue those hosts for automatic discover-marked-hosts
Can be restricted to certain check types. Write '--checks df -I' if you just
want to look for new filesystems. Use 'check_mk -L' for a list of all check
types. Use 'tcp' for all TCP based checks and 'snmp' for all SNMP based
checks.
-II does the same as -I but deletes all existing checks of the specified
types and hosts.
Additional options:
-I, --discover Delete existing services before starting discovery
--checks C Restrict discovery to certain check types
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-n, --no-submit Do not submit results to core, do not save counters
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-v, --verbose Enable verbose output (Use twice for more)