Why isnt Active/Active the norm?

The short answer is that all of this is currently changing. Aaron's answer (the first line) is spot on for most environments. In a 10.x world, you could run both active / active, and with VS creep over the years, you would reach a point where the boxes could not fail over for one another in terms of traffic load. In 11.x, with device clustering, you can run active / active / passive. Or active / active / active / passive / passive (you get the point) - As Aaron pointed out.

 

 

I have set up a few active / active configurations. Most were on VIPRIONs, and running vCMP, but that's beside the point. What I am looking for in the future is clustering between physical and virtual hosts which, IMHO, would be very cool, and something that folks ask about all the time.

 

 

CPU, memory, throughput, SSL transactions per second - These are the limiting factors you run into when running active / active. Keep this in mind, and remember - PLAN IT OUT FOR FUTURE GROWTH!!!!