Netapps deliver a lot of data. It could be that checkmk runs in to a timeout.
Try to adjust:
- Timing settings for SNMP access
- Service check timeout
Also it could help to disable inline SNMP with:
- Hosts not using Inline-SNMP
It use NET SNMP utils and consumes more resources but is faster.
Beside that I would try with snmpwalk if you could walk beyond OID .1.3.6.1.4.1.789.1.2.3.2 o r if it hangs there.
regards
Michael