What do you plan do with your SAN? If you are running typical applications on your VMs, like SQL, Exchange, File and Print, you will find the bottleneck to be in the RAID controller and the number of disks that it controls. Yes, a 15k SAS drive can push a lot of throughput, but that throughput is based on a large transaction size and a finite number of I/O operations per second (IOPS). If your 15k SAS drive does 200 IOPS (a reasonable number) and the payload is Exchange (8kB transfers), then the throughput of your SAS drive is at most 200x8kB = 1.6MB/s. And that doesn't include any IOP penalties for RAID5. I would encourage you to consider investing in more drives rather than in an expensive fabric. Using the math above, you can quickly see how 10 drives won't fill even a single gigabit Ethernet link. On the other hand, if you expect to spend time pushing large sequential reads or writes with an application, throughput could be an issue. I suspect that such a payload is a special case and virtualizing a system with that kind of payload will not deliver the desired results no matter how big and expensive the fabric. I hope this helps...good luck to you...sounds like a fun project!
