Using USB 3.0 to speed up USB 2.0 hubs.

[Jonathanese]

This isn't a question about some piece of hardware I currently have. It's more of a hypothetical question.


When a USB hub has multiple devices connected to it, it splits the bandwidth accordingly. So two USB devices plugged into a hub won't quite the the full bandwidth of a single device plugged into the port.

In the case of USB 3.0, they added the 5 additional wires to increase bandwidth. In a USB 3.0 hub, the data is distributed as I said before.


But what about USB 2.0 devices plugged into a USB 3.0 hub? From what I understand, it just uses the 4 main pins, and distributes the 480Mbps across all the devices.

But why not have the Hub distribute the USB 2.0 signals across the USB 3.0 bus? The way I figure, you could have 10 USB 2.0 devices running at full 480Mbps, for a total of 4,800Mbps, then have the hub communicate with the computer on the 5Gbps USB 3.0 bus.


Is this something they do yet/already? The way I figure, that would be one of the most widespread uses of USB 3.0 because it can use the extra speed to connect a plethura of existing 2.0 devices.

 

[randomhkkid]

This isn't a question about some piece of hardware I currently have. It's more of a hypothetical question.


When a USB hub has multiple devices connected to it, it splits the bandwidth accordingly. So two USB devices plugged into a hub won't quite the the full bandwidth of a single device plugged into the port.

In the case of USB 3.0, they added the 5 additional wires to increase bandwidth. In a USB 3.0 hub, the data is distributed as I said before.


But what about USB 2.0 devices plugged into a USB 3.0 hub? From what I understand, it just uses the 4 main pins, and distributes the 480Mbps across all the devices.

But why not have the Hub distribute the USB 2.0 signals across the USB 3.0 bus? The way I figure, you could have 10 USB 2.0 devices running at full 480Mbps, for a total of 4,800Mbps, then have the hub communicate with the computer on the 5Gbps USB 3.0 bus.


Is this something they do yet/already? The way I figure, that would be one of the most widespread uses of USB 3.0 because it can use the extra speed to connect a plethura of existing 2.0 devices.

[strike]I'm not sure it runs this way. The USB hub will have a usb 2.0 controller that communicates to the host port on the computer at a set speed. Even if the host port is 3.0 because a USB 2.0 hub is connected then the aggregate speed of all the devices on the hub cannot exceed the usb 2.0 standard.
[/strike] Ignore read question wrong

If you plug in USB 2.0 devices ie multiple hard drives into a usb 3.0 hub then they will all run at USB 2.0 maximum speed of roughly 30 MBps if required, due the higher bandwidth of 3.0. So yes theoretically if you plugged in 10 usb 2.0 HDDs to a 3.0 hub you could technically saturate it.

 

[laviniuc]

the problem in your reasoning is that you'll never find a usb hub featuring 3.0 conn to pc and 2.0 for the devices. they are usually either 2.0 all ports or 3.0 all.

 

[randomhkkid]

the problem in your reasoning is that you'll never find a usb hub featuring 3.0 conn to pc and 2.0 for the devices. they are usually either 2.0 all ports or 3.0 all.

USB 2.0 devices will work perfectly in a 3.0 hub, the ports are backwards compatible.

 

[Jonathanese]

I agree. The idea is that you would have all USB 3.0 ports, but the data from USB 2.0 devices would be sent back via the 3.0 interface.

I suppose it's similar in product philosophy to how Blu-Ray players can "upconvert" DVDs. The newer technology can also provide benefit to existing technologies, so you don't need the new media to take advantage of it.

 

[Jonathanese]

If you plug in USB 2.0 devices ie multiple hard drives into a usb 3.0 hub then they will all run at USB 2.0 maximum speed of roughly 30 MBps if required, due the higher bandwidth of 3.0. So yes theoretically if you plugged in 10 usb 2.0 HDDs to a 3.0 hub you could technically saturate it.

Okay, if I understand you correctly, USB 3.0 hubs already do what I was saying.

 

[randomhkkid]

If you plug in USB 2.0 devices ie multiple hard drives into a usb 3.0 hub then they will all run at USB 2.0 maximum speed of roughly 30 MBps if required, due the higher bandwidth of 3.0. So yes theoretically if you plugged in 10 usb 2.0 HDDs to a 3.0 hub you could technically saturate it.

Okay, if I understand you correctly, USB 3.0 hubs already do what I was saying.

Yes.The whole hub is restricted by the limits of usb 3.0, however because it's controller supports 3.0 speeds it can support many usb 2.0 devices running at full speed.

Though if you plan to be running lots of high speed usb 2.0 devices I'd suggest getting a good quality hub with a solid power supply.

 

[laviniuc]

the problem in your reasoning is that you'll never find a usb hub featuring 3.0 conn to pc and 2.0 for the devices. they are usually either 2.0 all ports or 3.0 all.

USB 2.0 devices will work perfectly in a 3.0 hub, the ports are backwards compatible.

backwards and forward compatible actually.

what he's asking is can he get a hub with one port 3.0 to use to connect to the pc on 3.0 and 10 usb2.0 to connect to all devices. that way they all work at the max 2.0 even if using just a single 3.0 connection.

and the answer is yes sure BUT if it's 3.0 for the pc conn the 2.0 ports he wants will actually be 3.0 by default. as the hubs are 2.0 (all ports) or 3.0 (all ports) in actual fact he-s future proofing the connections he wants as 2.0 for when he gets 3.0 devices. and as soon as 2 are added... the single conn to the pc becomes the bottleneck pretty much like the usb1.1 to 2.0 jump.

 

[randomhkkid]

the problem in your reasoning is that you'll never find a usb hub featuring 3.0 conn to pc and 2.0 for the devices. they are usually either 2.0 all ports or 3.0 all.

USB 2.0 devices will work perfectly in a 3.0 hub, the ports are backwards compatible.

backwards and forward compatible actually.

what he's asking is can he get a hub with one port 3.0 to use to connect to the pc on 3.0 and 10 usb2.0 to connect to all devices. that way they all work at the max 2.0 even if using just a single 3.0 connection.

and the answer is yes sure BUT if it's 3.0 for the pc conn the 2.0 ports he wants will actually be 3.0 by default. as the hubs are 2.0 (all ports) or 3.0 (all ports) in actual fact he-s future proofing the connections he wants as 2.0 for when he gets 3.0 devices. and as soon as 2 are added... the single conn to the pc becomes the bottleneck pretty much like the usb1.1 to 2.0 jump.

Yes forwards and backwards compatible is what I meant. From what I understand OP if you're planning on connecting 10 usb 2.0 flash drives to a 10 port usb hub that has a single connection to the PC then they will all run at maximum speed as long as the total combined speed does not saturate the 3.0 single connection to the PC.

 

[Jonathanese]

Here are some charts:

Current Method:

My Method: