I don't think they'd likely be way off what's available, but I also think if you're buying 5 Million drives (probably over X years) -- I'm sure you can get some customizations done. So, considering 4tb ssd drives are now arriving in consumer markets -- that does change the equation a bit. And if you plan for 16tb drives in the next 3 years?

http://www.theregister.co.uk/2014/04/29/sandisk_bigs_up_ssd_...