Certain companies (LSI, DDN) have enclosures that hold 60 hard drives in 4U of space. Why is it that these kinds enclosures aren't available unless you get them as a part of a "solution"? A 24 bay enclosure will run let's say four grand, why hasn't any manufacturer stepped up to provide that kind of chassis? Is there no demand, is the problem with heat management or do they actually exist and I'm just oblivious?
I've recently found out about a product from SuperMicro that I don't believe is available yet... 72 2.5" drive bays in a barebones unit.
SC417E series - Extremely High-Density 4U Storage Server Chassis
Third server from the bottom.
http://www.supermicro.com/products/chassis/4U/?chs=847 - 36 drives in 4U
Last one we purchased was $880 or so from our supplier.
http://www.supermicro.com/products/chassis/4U/847/SC847E16-RJBOD1.cfm - 45 drives in 4U, no room for motherboard, must be chained off another chassis. Listed at roughly $1500 at our supplier.
Not quite the density you're looking for, but, there are a number of companies that do it. If you can do 2.5", the solution listed above will probably have a very high build quality. We've used Supermicro almost exclusively since 1998.
Thats the biggest 4u disk beast i know of - 48 SATA.