What is eSATA?
eSATA stands for External Serial Advanced Technology Attachment and is also known as external-serial ATA. eSATA is a new standard that provides faster data transfer rates of up to 3Gb/s for external storage devices; easily tripling those of the Universal Serial Bus (USB) 2.0. Originally, SATA was designed to offer improved performance in data transfer between internal storage devices and PC's due to its serial architecture. Through eSATA, this feature has been extended to offer the same performance to external storage media. eSATA now takes SATA outside the box as an external standard allowing you the same speeds of an internal drive. The standard was released in 2004.
The main use for eSATA is external storage. eSATA enters an already crowded market of USB and FireWire interfaces which use either PATA or SATA drives. Some of eSATA’s strong points include the following.
eSATA's primary advantage is its significantly fast data transfer rate as compared to USB or FireWire 400. Bear in mind that USB was initially targeted for mice, keyboards, printers etc and not for large data transfers. eSATA uses a cable length of up to 2m outside the PC. Most eSATA cables are shielded and are therefore able to withstand more wear and tear. eSATA drives also have hot-plug capability. This means that you don’t have to shut down the system in order to attach or remove an eSATA hard drive.
eSATA does not need data translation since the data is already in a format that the computer understands. This means there is less lag (in terms of performance overheads) between the interface and the computer and therefore data can be pushed or pulled much faster. USB is an ATA drive with a bridge chip that translates from the ATA protocol to USB protocol used for the connection. It therefore requires en-capsulation of the transmit data and then de-capsulation after the data is received. eSATA allows multiple connections to an external array. Its port multiplication capability permits for grouping of up to eight Serial ATA hard drives in a RAID 0 (striped) array giving great performance. eSATA is becoming the external storage solution for many video and audio devices that require high transfer speeds as opposed to paying for Small Computer Systems Interfaces (SCSI). eSATA drives are known as ordinary drives in the BIOS. This means that it is possible to boot into Windows from an eSATA drive.
eSATA's main disadvantage is that it requires its own power cables. However, the SATA International Organization has announced that it is working on a new version known as Power Over eSATA that will allow the external drives draw power over the cable that connects the drive to the computer.
eSATA requires an external enclosure that specifically states that it supports an eSATA cable. For desktop or laptop computers that don’t have an eSATA connector, you can add a bus connector. Notebooks can use a peripheral component interconnect (PCI) card. eSATA has now been registered as an external standard, that has defined cables, connectors, and signal requirements.
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