1. How does USB 3.0 achieve the extra performance?

USB 3.0 achieves the much higher performance by way of a number of technical changes. Perhaps the most obvious change is an additional physical bus that is added in parallel with the existing USB 2.0 bus. This means that where USB 2.0 previously had 4 wires (power, ground, and a pair for differential data), USB 3.0 adds 4 more for two pairs of differential signals (receive and transmit) for a combined total of 8 connections in the connectors and cabling. These extra two pairs were necessary to support the SuperSpeed USB target bandwidth requirements, because the two wire differential signals of USB 2.0 were not enough.

Furthermore, the signaling method, while still host-directed, is now asynchronous instead of polling. USB 3.0 utilizes a bi-directional data interface rather than USB 2.0's half-duplex arrangement, where data can only flow in one direction at a time. Without getting into any more technical mumbo jumbo, this all combines to give a ten-fold increase in theoretical bandwidth, and a welcome improvement noticeable by anyone when SuperSpeed USB products hit the market. 

2. Isn't USB 2.0 fast enough?

Well, yes and no. USB 2.0 for many applications provides sufficient bandwidth for a variety of devices and hubs to be connected to one host computer. However, with today's ever increasing demands placed on data transfers with high-definition video content, terrabyte storage devices, high megapixel count digital cameras, and multi-gigabyte mobile phones and portable media players, 480Mbps is not really fast anymore. Furthermore, no USB 2.0 connection could ever come close to the 480Mbps theoretical maximum throughput, making data transfer at around 320 Mbps - the actual real-world maximum. Similarly, USB 3.0 connections will never achieve 4.8Gbps, but even 50% of that in practice is almost a 10x improvement over USB 2.0. 

3. What other improvements does USB 3.0 provide?

The enhancements to SuperSpeed USB are not just for higher data rates, but for improving the interaction between device and host computer. While the core architectural elements are inherited from before, several changes were made to support the dual bus arrangement, and several more are notable for how users can experience the improvement that USB 3.0 makes over USB 2.0:

More power when needed

o 50% more power is provided for unconfigured or suspended devices (150 mA up from 100 mA), and 80% more power is available for configured devices (900 mA up from 500 mA). This means that more power-hungry devices could be bus powered, and battery powered devices that previously charged using bus power could potentially charge more quickly.

o A new Powered-B receptable is defined with two extra contacts that enable a devices to provide up to 1000 mA to another device, such as a Wireless USB adapter. This eliminates the need for a power supply to accompany the wireless adapter...coming just a bit closer to the ideal system of a wireless link without wires (not even for power). In regular wired USB connections to a host or hub, these 2 extra contacts are not used.

Less power when it's not needed Power efficiency was a key objective in the move to USB 3.0. Some examples of more efficient use of power are:

o Link level power management, which means either the host computer or the device can initiate a power savings state when idle

o The ability for links to enter progressively lower power management states when the link partners are idle

o Continuous device polling is eliminatedo Broadcast packet transmission through hubs is eliminatedo Device and individual function level suspend capabilities allow devices

to remove power from all, or portions of their circuitry not in use Streaming for bulk transfers is supported for faster performance Isochronous transfers allows devices to enter low power link states between

service intervals Devices can communicate new information such as their latency tolerance to

the host, which allows better power performance

To paint an accurate picture, not everything in USB 3.0 is a clear improvement. Cable length, for one, is expected to have a significant limitation when used in applications demanding the highest possible throughput. Although maximum cable length is not specified in the USB 3.0 specification, the electrical properties of the cable and signal quality limitations may limit the practical length to around 3 metres when multi-gigabit transfer rates are desired. This length, of course, can be extended through the use of hubs or signal extenders.

Additionally, some SuperSpeed USB hardware, such as hubs, may always be more expensive than their USB 2.0 counterparts. This is because by definition, a SuperSpeed hub contains 2 hubs: one that enumerates as a SuperSpeed hub, and a second one that enumerates as a regular high-speed hub. Until the USB hub silicon becomes an integrated SuperSpeed USB + Hi-Speed USB part, there may always be a significant price difference.

Some unofficial discussion has surfaced on the web with respect to fiber-optic cabling for longer cable length with USB 3.0. The specification makes no mention of optical cabling, so we conclude that this will be defined in a future spec revision, or left to 3rd party companies to implement cable extension solutions for SuperSpeed USB. 

4. Will my existing peripherals still work? How will they co-exist? 

The good news is that USB 3.0 has been carefully planned from the start to peacefully co-exist with USB 2.0. First of all, while USB 3.0 specifies new physical connections and thus new cables to take advantage of the higher speed capability of the new protocol, the connector itself remains the same rectangular shape with the four USB 2.0 contacts in the exact same location as before. Five new connections to carry receive and transitted data independently are present on USB 3.0 cables and only come into contact when mated with a proper SuperSpeed USB connection. 

5. Where are those SuperSpeed USB 3.0 products? 

USB 3.0 silicon such as USB host controllers, peripheral chipsets and hubs compliant with the SuperSpeed bus have arrived in the latter half of 2009. Since then, a handful of external hard drives, flash drives, storage docks, Blu-ray optical drives, high-end notebooks, and host adapters in both PCI Express and ExpressCard have begun appearing on retail shelves. Other companies have shown their plans to roll outsolid-state drives and RAID. DisplayLink also revealed plans to ship USB 3.0-compliant USB videosilicons by Q4 2010.

It is important to note that NEC (now Renesas Electronics) and Fresco Logic are the only fabs to produce xHCI USB 3.0 host silicons as of this writing (October 2010). Until Intel, nVidia and AMD start bundling USB 3.0 as part of their motherboard chipset, companies interested in equipping USB 3.0 on their systems will have to source from said fabs for the chipsets.

Here's a list of commercially available SuperSpeed USB products:

Samsung Station STORYExternal Desktop USB 3.0 Hard Drives Buffalo HD-HUX3 DriveStation

3.5" based, available in 1TB, 1.5TB & 2TB. ioSafe SoloPRO USB 3.0

Rugged hard drive that can survive fire and water submersion. Iomega eGo Desktop 3.0

3.5 inch-based portable drive with native USB 3.0 interface.

Samsung STORY Station 3.0 Stylish SuperSpeed USB 3.0 3.5" drive in 1TB, 1.5TB and 2TB.

Seagate FreeAgent GoFlex Desk Desktop 3.5"-based 7200-rpm drive with optional USB 3.0 adapter.

Western Digital My Book 3.0 Hard Drive First commercially available USB 3.0 storage.

Seagate FreeAgent GoFlexExternal Portable USB 3.0 Hard Drives Data Locker DL3

256-bit AES XTS encrypted drive with keypad lock. Freecom Mobile Drive Mg

7mm single-platter drive in magnesium chassis. ioSafe Rugged Portable

Durable USB 3.0 mobile drive that is both waterproof & crush resistant. LaCie Rugged USB 3.0 Hard Drive

2.5" drive in a shockproof, waterproof enclosure. LaCie Starck USB 3.0 Mobile Hard Drive

2.5" drive in all aluminum chassis. Designed by none other than Philips Starck. Iomega eGo Portable 3.0

2.5 inch-based USB 3.0 drive with 256-bit AES HW encryption. Samsung S2 Portable USB 3.0

2.5 inch-based portable drive with native USB 3.0 interface. Seagate BlackArmor PS 110 USB 3.0

Portable 2.5"-based USB 3.0 drive, 1-port ExpressCard adapter bundled. Seagate FreeAgent GoFlex Ultra Portable

Portable 2.5"-based 5400-rpm drive with USB 3.0 adapter.

SIIG USB 3.0 Drive DockUSB 3.0 Drive Docks & Adapters Addonics USB 3.0 to eSATAp Adapter

A dongle connects to any eSATAp external storage.

Century CROS25U3 USB 3.0 Dock Bus-powered drive dock, made for SSDs & 2.5 HDDs. Available only in Asia.

Century CROSU3H USB 3.0 Dock 3.5" / 2.5" drive dock with integrated USB 3.0 hub. Available only in Asia.

Sharkoon QuickPort USB 3.0 Drive Station Drive dock for either 2.5" or 3.5" SATA drives.

Sharkoon QuickPort USB 3.0 Drive Station Bus-powered drive dock for only 2.5" SATA hard drives or SSDs.

SIIG USB 3.0 Hard Drive Dock A HDD dock with built-in fan that accepts both 2.5" & 3.5"

SIIG USB 3.0 to eSATA Adapter A dongle connects to any eSATA external drives up to 2TB.

Thermaltake BlacX 5G USB 3.0 Hard Drive Dock A simple dock that accepts both 3.5" and 2.5" drives.

Thermaltake MAX 5G USB 3.0 Drive Case 3.5" USB 3.0 drive enclosure with dual 80mm LED fans.

USB 3.0 RAIDsLaCie 2big USB 3.0 RAID

Buffalo DriveStation Quad SuperSpeed USB 3.0 RAID supporting 0/1/5/10 and JBOD.

Century CRNS35U3 USB 3.0 RAID Dual-bay enclosure with RAID-0, RAID-1 and JBOD mode.

Drobo S Drobo 5-bay RAID drive with USB 3.0, FireWire 800 and eSATA.

inXtron Orbit USB 3.0 RAID 2.5" based RAID-1 enclosure.

LaCie 2Big USB 3.0 RAID Symwave USB 3.0-based dual-bay RAID solution.

RAIDSonic Icy Box USB 3.0 RAID SuperSpeed USB two-slot enclosure with RAID-0, RAID-1 and JBOD function.

Kingston DataTraveler UltimateUSB 3.0 Flash Drives

A-Data Nobility N005 Available in 16GB, 32GB & 64GB with lifetime warranty.

A-Data S102 Budget USB 3.0 flash drive. Available in 8GB to 32GB with lifetime warranty.

Kingston Data Traveler Ultimate 3.0 Entry-level USB 3.0 flash drive with 80MB/s read, 60MB/s write.

Nexcopy USB 3.0 Duplicator First USB 3.0 duplicator for flash drives & hard drives.

Patriot Supersonic USB 3.0 Flash Drive Available in capacity from 32GB to 64GB. Top speed: 100MB/s.

PQI Cool Drive U368 USB 3.0 Flash Drive Available in capacity from 8GB to 128GB. Top speed: 105MB/s.

Super Talent USB 3.0 Express SuperSpeed USB flash drives for budget conscious.

Super Talent Express RAM Cache First flash drive with DRAM caching system to boost small block random speed.

Super Talent SuperCrypt First USB 3.0 flash drive with 256-bit XTS encryption.

Kingston HyperX Max SSDUSB 3.0 Solid-state Drives Astro Drive A101 Compact USB 3.0 SSD

Capacity ranging from 32GB to 128GB, tops at 180MB/s. Buffalo SHD-PEHU3 USB 3.0 SSD

Available in 64GB and 128GB. Top speed: 240MB/s. Only shipping in Japan. Iomega External USB 3.0 SSD

Up to 256GB. Speed tops at 250MB/s. Comes with v.Clone virtual PC software. Kingston HyperX Max 3.0

Powered by SDNow V+ with capacity from 64GB to 256GB. Top speed at 195MB/s. LaCie FastKey

From 30GB to 120GB. Speed at 260MB/s. With DRAM cache & 256-bit AES HW encryption.

OCZ Enyo Slim USB 3.0 SSD Available in 64GB, 128GB & 256GB. Speed tops at 200MB/s.

PQI S533-E USB 3.0 SSD Available in either 80GB or 160GB formidable X25-M 2.5" SSD.

Super Talent RAIDDrive First USB 3.0 flash drive in a self-contained RAID0 configuration; reaches 320MB/s.

Optical Media Drives Buffalo BR-X1216U3 Blu-ray Burner

Only shipping in Japan.

Multimedia devices BlackMagic Intensity Shuttle

First USB 3.0 HDMI video capture.

Networking J5Create Wormhole Station

USB 3.0 auto-switching KVM with 4.8Gbps direct connect network.

Asus U3S6 USB 3.0 CardUSB 3.0 adapter cards & hubs Century USB 3.0 ExpressCard

1-port USB 3.0 adapter fits flush in an ExpressCard slot. Asus U3S6 USB 3.0 / SATA 6Gbps Card

PCI Express 2.0 x4, two USB 3.0 ports, two SATA 6Gbps ports. Buffalo 4-port USB 3.0 hub

A pedestrian design; based on VIA USB 3.0 hub silicon. Cooler Master Storm Strike Force Cooler

A high-end notebook cooler with 4-port USB 3.0 hub. Gigabyte Ultra Durable USB 3.0 Card

PCI Express 2.0 x1, two USB 3.0 ports, 2700mA current to each port. LaCie Hub4 USB 3.0 Hub

Stylish 4-port USB 3.0 hub. PhotoFast 1-port USB 3.0 ExpressCard

Flush mounted USB 3.0 port on an ExpressCard. SIIG USB 3.0 Bay Hub / Card Upgrade Kit

USB 3.0 upgrade card with 4-port bay hub bundle. SIIG 4-port USB 3.0 Hub

The first SuperSpeed USB hub, powered by VIA 800 controller chip. StarTech USB 3.0 ExpressCard

ExpressCard 1.0, add two USB 3.0 ports on a notebook.

And this is a list of SuperSpeed USB products confirmed in development. They are either planned or concepts.USB 3.0 Products Reportedly in the Works

22.5" Displaylink-powered USB 3.0 Monitor Icron / Intersil 20m USB 3.0 Extension Cable USB 3.0 Movie Kiosk Point Grey USB 3.0 HD Camera

6. What is the future for USB 2.0? 

For at least the next five years, we do not see the market for USB 2.0 devices of all types to dwindle. High-bandwidth devices, such as video cameras or storage devices will likely be the first to migrate to SuperSpeed USB, but cost considerations, which in this industry are mainly driven by demand and volume, will restrict USB 3.0 implementation to higher-end products.

By 2010, computer motherboards should start to come equipped with USB 3.0 ports supplementing USB 2.0 ports. USB 3.0 adapter cards will likely play a large role in driving the installed base of USB 3.0 ports up, but as SuperSpeed-enabled ports become standard on new PCs, device manufacturers will be further motivated to migrate to the new standard.

In time, USB 2.0 may be phased out as was USB 1.1, but for now and the foreseeable future, USB 2.0 isn't going anywhere. 

7. What operating systems support USB 3.0?

At the SuperSpeed Developers Conference in November 2008, Microsoft announced that Windows 7 would have USB 3.0 support, perhaps not on its immediate release, but in a subsequent Service Pack or update. It is not out of the question to think that following a successful release of USB 3.0 support in Windows 7, SuperSpeed support would trickle down to Vista. Microsoft has confirmed this by stating that most of their partners share the opinion that Vista should also support USB 3.0.

SuperSpeed support for Windows XP is unknown at this point. Given that XP is a seven year old operating system, the likelihood of this happening is remote, as Microsoft in our opinion, will have to focus on the biggest bang for the buck applications.

With the open-source community behind it, Linux will most definitely support USB 3.0 once the xHCI specification is made public. Currently available under non-disclosure agreement in version 0.95 (a draft specification), organizations are forbidden to ship code because it might reveal or imply what is in the specification. Once that hurdle is out of the way, the Linux USB stack would have to be updated to add support for USB 3.0 details such as bus speed, power management, and a slew of other significant changes detailed in the USB 3.0 specification.

As is customary, Apple remains silent on the issue of SuperSpeed USB support in MacOS X. Our opinion is that if USB 3.0 realizes the promise of plug and play simplicity like USB 2.0 with dramatically increased speeds, the market for SuperSpeed devices will take off, and Apple will follow the trend. Whether or not this signals a threat to Firewire is not known, but you can be sure that Apple will need to support SuperSpeed if the rest of the industry adopts this interface standard.

Given the iterative nature of any software release, USB 3.0 O/S support will come in stages and phases, where initial support may be buggy, slow, or lacking in some features. Over time, these bugs will be ironed out, but expect some growing pains as systems migrate and the development teams struggle to catch up to the high expectations of the computing community at large. We will get there, but it will take time. Anyone remember how buggy and unstable USB support was in the MacOS in all versions of OS 8 and OS 9 before OS X 10.2 arrived? 

8. What new applications does USB 3.0 enable? 

In a nutshell, any high-bandwidth device that works with USB 2.0 will become better if updated with USB 3.0 support. At the moment, devices that tax the throughput of USB 2.0 include:

External hard drives - capable of more than twice the throughput available from USB 2.0, not to mention bus-powered portable drives that require non-compliant Y-cables to get the current they require for reliable operation

High resolution webcams, video surveillance cameras Video display solutions, such as DisplayLink USB video technology Digital video cameras and digital still cameras with USB interface Multi-channel audio interfaces External media such as Blu-Ray drives

High end flash drives can also push USB 2.0 pretty hard, and oftentimes if multiple devices are connected via hub, throughput will suffer.

USB 3.0 opens up the laneways and provides more headroom for devices to deliver a better overall user experience. Where USB video was barely tolerable previously (both from a maximum resolution, latency, and video compression perspective), it's easy to imagine that with 5-10 times the bandwidth available, USB video solutions should work that much better. Single-link DVI requires almost 2Gbps throughput. Where 480Mbps was limiting, 5Gbps is more than promising.

With its promised 4.8Gbps speed, the standard will find its way into some products that previously weren't USB territory, like external RAID storage systems. (Though, there are already plenty of USB-only RAID solutions (e.g. LaCie HDD Max, WD My

Book Mirror despite being limited by the interface.) 

9. How does USB 3.0 compare to competing interfaces (i.e. eSATA, FireWire 3200, ExpressCard 2.0)?

Firewire has long been the "forgotten" other mass market, high-speed interface standard. Previously available in Firewire 400 or 800 flavors, it has gradually fallen in popularity as USB 2.0 has surged. Apple, the inventor of the original IEEE 1394 "Firewire" standard, has repeatedly sent mixed messages with the ditching of Firewire first from iPods, and more recently from the mainstream MacBook laptops (except for the lowest-end MacBook, oddly enough).

In late 2007, the 1394 Trade Association announced Firewire 3200, called "S3200", that builds upon the existing Firewire 800 standard that was released in 2002. Utilizing the very same connectors and cabling that is required for Firewire 800, S3200 is basically a drop-in replacement once the internal system components are updated in devices. To date, S3200 has not gained much traction, even in traditional Firewire markets such as digital video.

Firewire's main claim to fame is that it is a highly efficient peer-to-peer, full-duplex, non-polling data communications protocol with very low overhead. Firewire delivers much higher actual throughput than USB 2.0, and can achieve much closer to its theoretical 800Mbps data rate than USB. Where Firewire 800 can deliver sustained data transfers of around 90MB/s, USB 2.0 hovers more around 40MB/s.

It remains to be seen what impact S3200 will have on the computing landscape.

eSATA, or External SATA, was brought to market in 2004 as a consumer interface targetted directly at an external storage market crowded with USB 2.0 and Firewire solutions. It successfully address the issue of the interface bottleneck, and allowed fast hard drives to fully realize their performance potential when located external to a server or PC. eSATA supports a data rate of 3.2Gbps, which is more than enough for the fastest hard drives, which can transfer about 120MB/s, easily better than USB 2.0 and significantly better than Firewire 800.

eSATA is not without drawbacks, however. Cable length is limited to a mere 2m, it cannot supply power to devices connected on the eSATA bus, and the connectors are neither small nor terribly suitable for consumer devices where aesthetics are important. Over the last several years, eSATA has steadily eroded both USB and Firewire market share in the data storage space, although its applications are limited, and really not well-suited to the portable device market.

ExpressCard 2.0 was released practically the same day as the USB 3.0 specification (November 2008) and promises to significantly enhance the ExpressCard standard for the increased speed requirements of today's mobile technologies. Closely tied to both the PCI Express and USB 3.0 specifications, ExpressCard 2.0 supports a variety of applications involving high throughput data transfer and streaming. Maintaining backwards compatibility with the original ExpressCard specification, the hot-pluggable interface standard for I/O expansion in smaller form-factor systems will by definition co-exist with the world of USB 3.0 devices.