HCL: I/O Compatibility Guide For ESX Server 3.5 and ESX Server 3i
VMware ESX Server Software delivers high performance I/O for PCI-based SCSI, RAID, Fibre Channel, and Ethernet controllers. To achieve high performance, these devices are accessed directly through device drivers in the ESX Server host, and not through a host operating system as with VMware Workstation and GSX Server products.
VMware certifies that specific systems and components are compatible with ESX Server software. Through the VMware Preferred Hardware Partner Program, ESX Server software works with leading server vendors to ensure that appropriate configurations of their current and future server products are certified.