[collectd] Thresholds, updated

[Jeremy Hanna]

So after looking at the docs a little more I ended up with this as a
configuration for the df threshold:

<Threshold>
    <Plugin "df">
        <Type "df">
            FSType "ext3"
            Percentage true
            ReportReserved true
            FailureMin 2
        </Type>
    </Plugin>
</Threshold>

Is that correct syntax?  Should that fire if the ext3 type filesystems
exceed 2% capacity?

I'm still not sure if the Plugin wrapper is needed...

Thanks.