The new PERC 5 and PERC 6 RAID controllers use SAS (Serial Attached SCSI), and a new driver, megaraid_sas. The new SAS 5 and SAS 6 non-RAID controllers use a new driver, mptsas, part of the mptfusion driver family. Both drivers are included in kernel.org 2.6.x kernels, and have been backported to the RHEL3 2.4.21-x kernels.
Energy efficiency is not related just to power (kWh) requirement, or cooling requirements, or performance (MIPs) - it pertains to all of these variables. And it's not just a data center issue - it is critical for organizations of all sizes and scopes. To get started improving your energy efficiency, use the Dell Data Center Capacity Planner to understand how your choices impact your energy use.