eSATA: five times faster than USB
New spec to revolutionise external drive connections.
By Chris Mellor | Techworld | Published: 11:40, 04 March 2005
External Serial ATA drives will transfer data five times faster than USB 2.0, according to a demo at Intel's Developer Forum.
eSATA II is capable of 300Mbit/s while USB 2.0 crawls behind with 45Mbit/s and even the first SATA spec manages 150Mbit/s. Seagate, with the help of NetCell, demonstrated the new technology yesterday with its marketing VP Jeff Loebbaka saying it showed eSATA's "ease of use and fast data transfer rates".
The demo was at SATA I speed, 150Mbit/s, and used two Seagate eSATA 160GB, 7200-rpm, 8MB cache external hard drives with a NetCell eSATA PCI RAID card. Such eSDATA drives could be used to build an external RAID array for servers.
An eSATA backup to an external disk could complete in 10 minutes instead of 50. Some vendors have used internal SATA ports but outside the box. However that "pointing-out" of an internal SATA port is not compliant with the eSATA spec and doesn't supply the robust and easy-to-use connectors that the eSATA spec designates, or the shielded cables that preserve signal integrity.
The SATA I/O organisation "owns" the external SATA specification. It was developed because SATA drive vendors realised that, although SATA was intended as an inside-the-box specification, there was no reason why it couldn't be used to connect external SATA drives to a PC or server system. The specification was released in mid-2004 and details the shielded round cables, connectors and signals.
Shielded cables up to 2m long are used to connect drive and system via robust and easy-to-use connectors. The eSATA devices are hot-pluggable so it is perfect for connecting external drives used as backup or file transfer devices.
This doesn't mean the end of USB. It is simply too useful as a general plug-and-play PC and server interface for all kinds of peripherals, from mice to scanners. Unfortunately, because USB speeds have not kept up with the needs of external disk I/O, the eSATA spec will likely become popular and be added to PCs as a standard fitting. This will put an end to the unifying port simplification provided by USB.
