InsightIQ - typically abbreviated to IIQ - is a decent reporting tool. It collects the data from your clusters but does not make any recommendations.

You can get similar results by developing your own tools and collecting the data.  Although I use InsightIQ for all 8 of my clusters, I also have some of my own tools that load data into Graphite for display.

The File System Reporting tab is simply a very basic web-based interface into the FSA data that the Isilon already collects and stores into a sqlite3 database.

> such as can also be used in node expansion decision of Isilon.

The decisions are made on 2 basic factors:  capacity and performance.  IIQ is not a great capacity planning tool and you're probably better off developing your own or going to a 3rd-party.  It makes no effort to graph historical data on any of the CIFS or NFS volumes you may have but only looks at the overall data.  IIQ is pretty good at looking performance - that's its most important feature and I use it regularly to see what was going on at a specific point in time.  You can look at your latency trends and add or upgrade nodes based on an increase in latency or an increase in your protocol operation rates that may suggest you are going to increase latency in the future.  It will tell you exactly what kind of protocol operation is contributing to your overall operation rate and what the latency is for each specific operation.  For example, if you're heavy metadata read, you may make a different expansion or upgrade decision than if you're heavy write.

IIQ is still a pretty immature product and it's getting better every release.  IIQ 3.1 added several new features.

IIQ does not do any alerting at all.  It only collects the data and presents it in a web UI.   I don't know if alerting is on a roadmap - if it is, I haven't heard about it, not even under NDA - and this is still a major shortcoming for me.

IIQ is a good tool to own but you still need other tools, some of which EMC doesn't even have available to sell you.