I would appreciate if someone can point me to step-by-step instructions on monitoring AS/400 via SAM. Any documentation or pointers would be greatly appreciated.
AS400 has fairly limited information available to you via SNMP, which you would monitor the same as any other SNMP based device in Solarwinds. There are a few vendors who have created custom SNMP agents you can install to replace the built in SNMP agent with a more complete one, unfortunately these are not free. The example I've seen cited most often is by a company called Comtek
COMTEK Home Page