I’ve been building a little SNMP Management Pack in the past few days to discover and monitor a bunch of PowerWare UPS’s, which turned out to take quite a lot more energy and time than expected. Mostly due to the facts that I am really bad with SNMP and how it works, I’ve never really looked into the inner working of building an SNMP management pack and also because we ran into a couple of errors preventing the discovery process to work alright.

To make it clear right away, this is not going to be a “Building an SNMP Management Pack Tutorial” since there’s plentiful good ones out there already, and to be extra helpful I’m gonna include a few links right away:

• SNMP Setup and Simple Custom SNMP Discovery – Pretty much the basics
• SNMP Management Pack Example: NetApp Management Pack – Part 4 actually, but has the links to the other parts
• Creating SNMP Probe Based Monitors – No custom discovery, but a good and simple guide to SNMP Probes

It’s the second, the NetApp one, I’ve used as a guide to building the UPS management pack since it goes through the process of building your own filtered discovery using SystemOID to identify your hardware-classes and then building the monitors on top of those.

Let’s get to it

When building the discovery of my hardware classes I ran into problems. The discovery simply did not work. At first I got some strange errors about “invalid queries”, something that turned out to be related to me reading two guides–seriously though, pick one guide that is closest to what you want to achieve and stick to it–and mixing up the XPathQuery variables. Silly me.
I got those errors to go away and I was able to get a few objects to my base-class, but none of the hardware classes who was populated through the return value of an SNMP OID got discovered.
The only error I got this time was the following:

Log Name:      Operations Manager
Source:        Health Service Modules
Date:          2010-09-02 11:19:12
Event ID:      11001
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      CENSORED
Description:
Error sending an SNMP GET message to IP Address XX.XX.XX.XX, Community String:=CENSORED, Status 0x6c.

One or more workflows were affected by this.

Workflow name: CENSORED.MP.CLASS.DISCOVERY
Instance name: CENSORED_DEVICENAME
Instance ID: {5C7EFB30-D885-8843-0DD7-EA86B4FD2311}
Management group: CENSORED

<IsWriteAction>false</IsWriteAction>
<IP>$Config/IP$</IP>
<CommunityString>$Config/CommunityString$</CommunityString>
<Version>1</Version>
<SnmpVarBinds>
	<SnmpVarBind>
		<OID>1.3.6.1.4.1.534.1.1.1.0</OID>
		<Syntax>0</Syntax>
		<Value VariantType="8"></Value>
	</SnmpVarBind>
	<SnmpVarBind>
		<OID>1.3.6.1.4.1.534.1.1.2.0</OID>
		<Syntax>0</Syntax>
		<Value VariantType="8"></Value>
	</SnmpVarBind>
	<SnmpVarBind>
		<OID>1.3.6.1.4.1.534.1.1.3.0</OID>
		<Syntax>0</Syntax>
		<Value VariantType="8"></Value>
	</SnmpVarBind>
</SnmpVarBinds>