for internal use only?

How many of those controllers for servers were for internal use only? I think Dell's PERC is LSI based, and even on the latest R610 that I've seen I didn't see any indication that the internal controller had any way to connect something externally to it. Sure you can get a PCI expansion board for external DAS but the number of folks doing that seem pretty low these days, perhaps it's growing. DAS works fine I think if your workload is fairly static and you know how much capacity you need. Amazon I believe uses it for their Oracle DBs(last I heard at least). In situations where there is a lot of uncertainty, using DAS can be horribly inefficient. Although compared to some legacy SAN technologies it may still be comparable.