Appreciate the quick replies. Glad to know that controller chip is supported. SeanLeyne, I understand what you are saying about the data transfer rates of current hard drives. Thanks for the detail. As opposed to thinking that I was gaining performance with the expanders, I was worried about losing it by trying to carry too much traffic down a single 4-lane. I'm having a bit of a tough time visualizing exactly what you are saying about connecting the "4 expanders -- each connected to 3 backplane channels." To take a stab at it, for a 48-drive solution, you would generally recommend one big controller with say 4 mini-SAS 4-lane outputs. Each of the mini-SAS connections would go to a 4-port expander (1-in 3-out) and each of the 3 expander outputs would then connect to 3 backplane channels (each channel commonly correlates to a row of four 3.5" drives). That means that at it's heaviest load, the traffic from 12 drives are getting hauled between the expander and the controller (the smallest pipe) in one 4-lane at up to (4x6Gbps) 24Gbps. Since any one drive isn't likely to exceed 1.8Gbps, the total of their traffic wouldn't exceed (12x1.8Gbps) 21.6Gbps. Am I understanding that correctly? May I ask you what controllers/expanders/chassis you are using? I am pretty set on Intel, but, it would sure be nice to look at what else it out there. I did see SuperMicro had some pretty slick chassis designs. I will definately take a closer look. Thanks again!