We just purchased a dell storage server with (12) 7200 RPM SATA drives running RAID 10 and (4) gigabit network interface cards. Additionally it has a PERC H700 controller card with 512MB of on-board cache. We will be attaching hypervisors to the dell server (block level storage), which will store virtual machines.
Our question is, using iSCSI, and a single gigabit connection between each hypervisor and the dell storage server, is it true that maximum theoretical transfer rate per hypervisor would be 1000 Megabits / 8 = 125 Megabytes a second? Or, am I completely wrong, and iSCSI does some sort of compression and is able to achieve higher I/O throughput rates.
125 Megabytes a second actually is somewhat slow seeing as we have 12 spindles and running RAID 10. What are some alternatives, besides fiber channel to remove the network bottleneck? We are aware of enabling jumbo frames, and will give that a try, anything else. What sort of performance should we expect using a single gigabit connection per hypervisor?