Re: Keepalived loses contact with snmpd when snmpd restarts

On Thu, Apr 23, 2015 at 5:25 PM, Vincent Bernat <[email protected]> wrote:
> Did you wait long enough for keepalived to notice that it should
> reestablish connection with snmpd? Because reconnecting to the agent can
> block keepalived, this is only done seldomly. You have to wait 2
> minutes. More on this here:
>  http://vincent.bernat.im/en/blog/2012-fixing-async-agentx.html

Ah!  That explains the variability of my results.  Yes, waiting 2 minutes
solves the problem.  It also explains why when I automated my test cases
things failed more frequently: manually testing was more likely to find me
reading email for 2 minutes before continuing.  Thank you for the
explanation!

I checked syslog and there are no messages when it is disconnected.
However, once it connects there is a flood of messages:

Apr 23 14:36:51 client1 Keepalived_vrrp[15896]: NET-SNMP version 5.5 AgentX
subagent connected
Apr 23 14:36:51 client1 Keepalived_healthcheckers[6477]: NET-SNMP version
5.5 AgentX subagent connected
Apr 23 14:36:51 client1 snmpd[16104]: duplicate registration (AgentX
subagent 7, session 0x7f69ef55fc20, subsession 0x7f69ef571400, AgentX
subagent 5, session 0x7f69ef55eda0, subsession 0x7f69ef570d60)
Apr 23 14:36:51 client1 Keepalived_healthcheckers[6477]: registering pdu
failed: 263!
Apr 23 14:36:51 client1 snmpd[16104]: duplicate registration (AgentX
subagent 7, session 0x7f69ef55fc20, subsession 0x7f69ef571400, AgentX
subagent 5, session 0x7f69ef55eda0, subsession 0x7f69ef570d60)
Apr 23 14:36:51 client1 Keepalived_healthcheckers[6477]: registering pdu
failed: 263!

The last 2 messages repeat 9 times total.  In all my testing this has been
consistent.

Rather than waiting 2 minutes, would it be possible to start by trying to
connect then, if that fails, wait 2 minutes to re-try?  It is usual for a
program to take a little bit of time to start up, but having some features
fail for the first few minutes is surprising.

Thanks!
Tom

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