Re: Isilon slow?
The Isilon has two series: the X series geared towards sequential video streams (like NetApp's LSI arrays) and the S series geared towards random I/O.
From the specfs benchmark which does test a good chunk of random workload: the Isilon S200 series hits 1.6 million and the largest 24x node NetApp 8.1 cluster hits 1.5 million. So I'd say that fully popped either platform can do an "oh my god" level of random I/O for an "oh my god" price point.