I'm trying to measure performance of two storage arrays. One is not doing anything and the other has production system on it. When I run IOMeter on the system that has production on it, are the numbers going to be skewed because it already has a load on it? Is the comparison going to be accurate in my scenario?

Also what is the proffered setting for # of Outstanding I/Os per target? I've seen posts where people use 16 or 32. Is this setting supposed to be our average queue length?

Thanks