IBM iSeries / AS400 monitoring

I'm not familiar with the DSs that would have been given out during POV. The question remains, what exactly isn't working and how can the data be gathered manually?  If SNMPv3 is the method of choice, is the data desired available through that protocol?

Right now the DataSources being used are all custom scripts received during the POV and are unsupported. 6 of the 8 seem to work but SNMP v3 was causing issues with RAM Usage. For JOBS,  the previously monitored subsystems include QBATCH, QCMN, QCTL, QHTTPSVR, QINTER, QSERVER, QSPL, QSYSWRK, QUSRWRK, & Q1ABRMNET. Are these subsystems something that could be monitored easily?

I haven't ever built any AS400 modules. Have you checked the Exchange? 

The first thing I ask someone is what metrics they want to collect and how they would go about doing it manually. Do you use telnet/ssh? Do you use SNMP? Is there an API (guessing since it's AS400, no)? Once you know how to gather the data manually, building the DataSource becomes a much simpler job.