It's common that a external SAS chassis had multiple connections that can access all drives. The one I use I believe has 12 connections for 60 drives. CPUs th

It's common that a external SAS chassis had multiple connections that can access all drives. The one I use I believe has 12 connections for 60 drives. CPUs these days generally have a PCIe controller inside. Socket 0 can use the direct connected HBA 0 to access all drives while socket 1 can use the direct connected HBA 1 to access all drives. On top of that each SAS drive has TWO connections to the SAS fabric. My favorite storage building block is two 60 disk chassis (120 drives) cross connected to two servers with 4 SAS connections each. So with 12gbit SAS that's 48Gbit per cable x 4 = 192 Gbit/sec or 24GB/sec per chassis. For extra performance I use NVMe inside the server for caching, with hit rates usually in the 75-90% range.