USB 3 in 2008, 10 Times as Fast

psychicsword writes "Intel and others plan to release a new version of the ubiquitous Universal Serial Bus technology in the first half of 2008, a revamp the chipmaker said will make data transfer rates more than 10 times as fast by adding fiber-optic links alongside the traditional copper wires." "The current USB 2.0 version has a top data-transfer rate of 480 megabits per second, so a tenfold increase would be 4.8 gigabits per second." This should make USB hard drives easier and faster to use."

Comments

I'm more concerned with latency.

[jimstapleton]

It seems current hard drives test to 40-80M/s (dunno if it's bit or byte, we'll assume byte since it is worst case for my example)., averaging between 50 and 60M/s

480Mbit per second = 60MByte per second. That can handle the average case for a modern hard drive.

4.8GBit/second - 600MByte/s? To utilize that with a drive, you'd need a RAID external enclosure!

Re:I'm more concerned with latency.

[Televiper2000]

My experience with USB is that it has lousy thru-put do to the way the drivers manage data on the host side. We did some heuristic timing tests on USB to serial devices and found that most of them actually degraded the thru-put (time send and receive a packet) of an RS232 connection. We found that devices with Silicon labs ICs could get the desired thru-put, but it seemed they would take up an entire USB channel to do so.

Re:Cable?

[YrWrstNtmr]

The last line in the article:
"It will be backward compatible, so current USB 2.0 devices will be able to plug into USB 3.0 ports."

Re:Great.

[morgan_greywolf]

1.5 seconds if you all of your components were fast enough. The drive won't be. Exactly. There's still the slowdown associated with the mechanical aspects of the hard drive -- spin rate (RPM), average seek time (ms), etc. On top of that, most hard drive controllers are limited by the technology they use. For instance, a SATA hard drive, even plugged into a USB 2 or 3 port, is limited to 150 MB/s -- but, that's burst speed, not sustained transfer rate.

Re:Great.

[Anonymous Brave Guy]

On top of that, most hard drive controllers are limited by the technology they use. For instance, a SATA hard drive, even plugged into a USB 2 or 3 port, is limited to 150 MB/s -- but, that's burst speed, not sustained transfer rate.

Indeed. And realistically, it's going to be a pretty short burst: most hard drives today only have something like 8–16MB of cache that might be filled by a smart lookahead algorithm, so your best case with current hard drive technology is that you'll get perhaps 1/10 of a second of high-speed data transfer before hitting the physical barriers.

I'm not sure this is directly applicable to this discussion, though, because AFAIK all current USB drives use different storage technology anyway. It's going to be the limits of that technology that tell us whether USB3's theoretical speeds will actually be useful with storage hardware available in the same time frame.

What about PoE

[Anonymous Coward]

Ethernet is all signal, no power. You couldn't charge your iPod or iPhone with your sync cable, nor would your mouse or keyboard work without batteries.

That would be "Power over Ethernet".

http://en.wikipedia.org/wiki/Power_over_ethernet

Re:Honest Question

[smellsofbikes]

A bunch of other people have chimed in with parts of the answer already, and I thought I'd add some more.
Obviously each manufacturer wants you to use their standard and buy their hardware.
Different implementations came through at different times, and have different amounts of software/hardware overheads, and try to do different things.
RS232 has almost no necessary software overhead -- you do any and all the work with code you write. USB has *quite* a bit of software overhead to deal with device identification, and Ethernet has *enormous* amounts of overhead. In most small systems you have to buy an Ethernet software stack separately from the OS you're using.
USB tries to provide power. People are trying to glue power into Ethernet although it hasn't yet taken off.
People keep going off in odd wireless directions.
The fundamental problem, I think, is that there are several different connectivity needs and manufacturers are trying to get you to buy their solution to what they think are the most important needs. What you're asking for is something good for the industry in the long term, and that's not really in the direct interest of any particular company, so nobody's building anything for it.
The military embedded market seems to be moving towards gigabit or 10-gig fiber ethernet for all their interboard communications, but fiber has its own problems, and I'm not sure it's the right thing for a USB key you're carrying in your pocket all the time.
I believe that the SCSI module in linux handles firewire and USB, so from that standpoint it looks like it's a start towards universal communications, except for Ethernet. (Even though old SCSI is nothing like serial: it's the the ultimate expression of parallel communications, with some similarities to the old HP/GPIB parallel communication standard that's still used in for test communication but used to be a hard drive standard.) I have no idea what Windows does.

0.9 TB / 4.8 Gb/s = 1500 seconds

[Anonymous Coward]

WTF, a chain of "Exactly" and "Indeed", and no one realizing that 1.5 seconds is wrong by a factor of 1000?

Re:Cable?

[ddstreet]

> like if you plug a usb 1.X device onto a usb 2.0 bus, then everything slows to usb 1.X. IINM...

This is wrong, if you plug a USB 1.1 device into a USB 2.0 "bus" then it does NOT slow everything down. Specifically there are 2 cases:

1. You plug a USB 1.1 device directly into your computer (i.e. directly into the "host controller"). In this case, the USB 2.0 host controller (technically a EHCI chip) does NOT talk to your device. Instead, the EHCI chip has one or more USB 1.1 host controller chips (technically either a OHCI or UHCI chip, and called a "companion" chip when inside a EHCI chip) and your USB 1.1 device is connected electrically to that controller. You device is not on the USB 2.0 (EHCI) bus.

2. You plug a USB 1.1 device into a USB 2.0 hub. In this case, the USB 2.0 hub creates a complete USB 1.1 environment specifically for your device. On the host-facing side of the USB 2.0 hub, all communication continues to take place at USB 2.0 (i.e. 480Mbps) speeds. When the host wants to talk to your USB 1.1 device, it uses what is called "split transactions" to talk to it. Basically (I'm simplifying), this involves sending a "start" packet to the USB 2.0 hub. Then, the USB 2.0 (EHCI) controller goes on to do other things, while the USB 2.0 hub initiates the transfer to your device at USB 1.1 speeds. And data transferred from the USB 1.1 device is stored temporarily in the USB 2.0 hub. Eventually the USB 2.0 (EHCI) host sends a "finish" packet to the USB 2.0 hub. If the USB 1.1 transation finished, the USB 2.0 hub responds successfully (either with the incoming data or a "ack" that the outgoing data was sent) which completes the transation.

(There is also a combination case of those, where the EHCI chip does not contain a "companion" USB 1.1 chip, but instead contains an internal USB 2.0 partial hub - the "transaction translator" part - that handles talking to USB 1.1 devices. For bus usage purposes, this is effectively the same as using an external USB 2.0 hub, since the USB 1.1 devices do not appear on the USB 2.0 bus.)