Thursday, January 21, 2010

Why USB 3.0 is much faster than USB 2.0?

For 2010 the major topic will be surrounding over new USB 3.0 and SATA 6Gbps devices, and we are seeing more and more device manufacturers are announcing their USB 3.0, SATA 6Gbps products.

As you might have seen introduction of USB 3.0 devices, claiming that it is 10x faster than the previous generation USB 2.0, but how is it really acheived and what the technology behind that? Here I'll use a simple illustration to explain it.

The theoretical bandwidth of USB 3.0 is 5Gbps(Gigabits per second) and data transfer rate upto 500MBs(Megabyte per second), it is made possible by having an extra pair of data path compared to previous USB 2.0. But what really makes the great difference is the data transfering method.

Looking at the above illustration, USB 2.0 interface is using a "Half Duplex Transfer" method where data are transmitted in a single pathway. During transfering data from the host PC to USB device, it is required to wait for the host pc sending data to USB device is completed before USB device could transfer data to the host PC. This will lead to a long waiting time for data transfer between 2 devices, resulting a poor performance.

As for USB 3.0 interface with an added pair of data path, data transfer is more efficient as it is able to receive and send data at the same time, this method is called "Dual Simplex Transfer". A more simple example to explain this concept is looking at the road traffic, the road is separated into 2 different direction to prevent cars crashing into each other. If you can consider the cars as the transfer data without having any traffic jam, you are able to get a higher transfer rate at a 2 way street over one-way street.

I do hope the above brief explaination could give you a better understanding to the new technologies. Do feel free to leave any comments.

1 comment:

  1. Ever been copying files to an external USB 2.0 backup drive and noticed how the time remaining doubles or triples when you drag and drop another file? That won't happen with USB 3.0's Dual Simplex Transfer - well not as severe anyhow.