USB 3.0 Speed and Compatibility
In late 2008, version 3.0 of the USB specification was released to the USB-IF, which enabled developers to begin implementation in future products.
For a product to be classified as USB 3.0 compliant, it must meet several requirements. From a performance standpoint, two of the objectives that must be met for a product to be certified as USB 3.0 compliant are:
Support for data rates of up to 5Gbps
Backward compatibility with USB 2.0
With a data transfer rate of 5Gbps – roughly 10x as fast as was specified in USB revision 2.0 and 400x times as fast as the original USB specifications (1.0/1.1), USB 3.0 delivers a solution that more suitably harnesses the capability of modern storage devices and the large file sizes of high quality media.
Although the speed supported by USB 3.0 would be overkill for external hard drives to date, given the current mechanical performance capabilities of the drives, USB 3.0 is the ideal solution for various RAID applications (RAID 0) or SSDs (Solid State Drives) wherein drive data transfer rates exceed those supported by USB 2.0 or eSATA.
Based simply on the number of USB devices that have shipped to date worldwide – estimated at 10 billion7 and counting – the backward compatibility of USB 3.0 with USB 2.0 is vital.
Although for a device to utilize the full capability of USB 3.0, a USB 3.0 compliant host bus and USB 3.0 cable are required, a USB 3.0 device (such as a USB 3.0 external hard drive enclosure, or USB 3.0 hard drive docking station) would still be able to function at typical USB 2.0 speeds when connected to a USB 2.0 host8. This is extremely important as it means much less expense for users who would have had to replace their existing USB devices with newer models for the sake of compatibility with the new standard.
Another core benefit of USB 3.0 is its power efficiency, which is more conducive to energy conscious computer architecture. Some of the main power management enhancements are:
Replaces continual Device Polling with asynchronous notifications, utilizing fewer system resources
The introduction of link power management states, which enable power savings when the connection between the host and the device is idle
The transition to low power states can be initiated by either the host or the device, which helps minimize the amount of overall power drawn from the host
“Suspend” capabilities that enable devices to remove power from all of their circuitry or only portions of the circuitry that are not in use