eSATA is an extension to Serial ATA standards to enable SATA drives to be attached externally. Before eSATA, external hard drives were connected via USB or FireWire. eSATA can provide data transfer rates significantly faster than USB or FireWire. eSATA 1.
5 offers data rates up to 150MBps. eSATA 3G doubles that to 300MBps. eSATA cables can be up to 2 meters (approximately 6 feet) in length. eSATA drives are hot-pluggable, meaning that you can attach or remove an eSATA hard drive from a system without powering down the system or the drive.
Lisa Parker writes on topics such as ESATA , RAID and Mirroring for The Tech FAQ.