There are many types of hard drives that you can use for your workstation or server computers such as IDE, SATA, SCSI, Solid State and now SAS or Serial Attached SCSI.
Serial Attached SCSI delivers new levels of speed and connectivity while retaining the functionality and reliability that has made SCSI so dominant for years. SAS provides greater dedicated bandwidth with smaller connectors and uses point-to-point disk drive interfaces. SAS provides backwards compatibility with certain SATA drives and offers advanced features from fiber channel and the physical interface from SATA along with the performance and reliability of traditional SCSI technology. The first generation of these products will deliver full-duplex performance at 3 Gb/sec.
Benefits of SAS:
Based on Serial technology
Cheaper than SCSI
Greater bandwidth scalability
Compatible with SATA
Designed to be extremely flexible
Simplified cable routing - no need to daisy chain devices
Smaller cable connectors
Longer cabling distances
Dual ported SAS drives for redundancy
Allows for smaller drives