https://collectd.org/ https://collectd.org/ does the gathering (and writing to RRDTool database, if you so desire) part very well. Many plugins, easy to add mor

https://collectd.org/ https://collectd.org/ does the gathering (and writing to RRDTool database, if you so desire) part very well. Many plugins, easy to add more (just return one line of text) Still need RRD viewere but that's not a huge stack And it scales all the way to hundreds of hosts, as on top of network send/receive of stats it supports few other write formats aside from just RRD files.