Cause of blank graphs on hp-ux: Stopped SNMP-subagent

[etc]

The environment is hp-ux version 11.23

I've multiple case of blank graphs, and despite the help on this forum (which usually means you are told to read the site in a signature file), I've traced the root of the problem - I have the SNMP subagent die. There is no way to check that it's running programmatically. There is no daemon or process to check for.

All I have to do is restart it -

/sbin/init.d/SnmpHpunix stop
/sbin/init.d/SnmpHpunix start


and voila, the graphs are created, the rrd files are meaningful again.