At the university, we use PRTG for all sorts of monitoring. I'd been working with porting our disk monitoring we currently do for Windows servers in perfmon alerts to PRTG. That seems to work fine and PRTG seemed like a good choice for monitoring Linux partitions seeing as we really hadn't had a good solutions for it yet.

The default included PRTG MIB libraries only included things like size of partitions and total used size. These aren't really useful for seeing if you are getting close to filling a partition. Thanks to this page, I was able to get the magic sauce to be able to see used percentage via SNMP which is actually useful in my case.

The disk entries in the snmpd.conf file mentioned in the help page mentioned above work for any partitions you need to monitor. The .1.3.6.1.4.1.2021.9.1.9.1 OID will always be the first disk entry in snmpd.conf and for each additional partition listed, just increment the last number of the OID to correspond to the partitions entry in snmpd.conf. So, for example, if you have / and /data listed, / would be .1.3.6.1.4.1.2021.9.1.9.1 and .1.3.6.1.4.1.2021.9.1.9.2 would be /data.

This has been very helpful for us in beginning to actually monitor linux disk space for our Ubuntu servers and I hope you find it helpful as well.

Cheers,
~miked