eSATA (External Serial Advanced Technology Attachment) is an external interface for SATA external drives competing with Firewire and USB. SATA is the replacement interface technology for the older ATA interface for HDDs (hard disk drive). While it is significantly faster than Firewire 400 or 800 and USB 2.0, eSATA does require a separate power connector. An advantage of eSATA over USB and FireWire is that it does not have to translate data between the interface and the computer. Also, eSATA supports low-level drive features such as S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology drive problem self test) which may not operate through USB or FireWire bridging.
eSATA cables can be up to 3.3 feet (1m) in length.
eSATA Transfer Speed Comparison
eSATA: 300MB/s
USB 2.0: 60 MB/s
FireWire 400: 49.13MB/s
FireWire 800: 98.25MB/s
